Wood Use: U.S. Competitiveness and

Technology—Vol. II

November 1984

NTIS order #PB85-156081
Recommended Citation:

Wood Use: U.S. Competitiveness and Technology—Volume II-Technical Report (Washington, DC: U.S. Congress, Office of Technology Assessment, OTA-M-224, November

1984).

Library of Congress Catalog Card Number 83-600567

For sale by the Superintendent of Documents

U.S. Government Printing Office, Washington, DC 20402
Preface

The Office of Technology Assessment assessed the role of wood in the U.S.

economy at the request of Senator Mark Hatfield, Chairman of the Senate Committee on Appropriations, and Senator Thad Cochran, Chairman of the Subcommittee on Agriculture, Rural Development, and Related Agencies, Representative

James Weaver, Chairman of the Subcommittee on Forests, Family Farms, and

Energy, joined in support of the assessment in the House of Representatives. The

final report of this assessment was published as volume I of Wood Use: U.S. Competitiveness and Technology, Representative Weaver requested that this second

volume, a technical report on wood technologies and wood use, be prepared.

Volume II reviews the status of wood manufacturing technologies and surveys

the current and future uses of wood products. It explores the existing or developing technologies and manufacturing processes that can enable the United States

to benefit from its vast timber resource. Technologies for increasing the growth

and production from the forest and the efficiency of harvesting and transporting

timber were treated in volume I.

- JOHN H. GIBBONS

Director

,., ///
Wood Use: U.S. Competitiveness and Technology Advisory Panel

Larry Tombaugh, Chairman

Department of Forestry, Michigan State University

Darius Adams Carter Keithley

Department of Forest Management Wood Heating Alliance

Oregon State University

Clark S. Binkley

School of Forestry and Environmental Studies

Yale University

Carroll Brock

M. G. Brock & Sons

Merle Conkin

National Forest Products Association*

M. Rupert Cutler

The Audubon Society

Peter Kirby

The Wilderness Society

Dudley Kircher

Mead Corp.

Bruce Lippke

Weyerhaeuser Corp.

Norma Pace

American Paper Institute

Carl Reidel

Center for Environmental Studies

Ormond Danford University of Vermont

Tree Farmer of the Year, 1980 John Ward

Robert D. Dav National Forest Products Association

Renewable Natural Resources Foundation Henry Webster

Kirk Ewart Michigan Department of Natural Resources

Boise Cascade Corp. lohn Zivnuska

Rodney Foil Department of Forestry and Resource

Mississippi Agricultural and Forestry Management

Experiment Station University of California at Berkeley

*John Ward replaced Merle Conkin on the ()’I’A Advisory Panel in October 1982.

Acknowledgments

Volume II was prepared by the Office of Technology Assessment Industry, Technology, and Employment Program staff. OTA wishes to acknowledge the assistance and cooperation of D. A. Tillman, A, J.

Rossi, and S. O. Simmons of Envirosphere Co., Bellevue, Wash., who contributed significantly to the assessment as contractors.

The staff also wishes to acknowledge the special contributions made by the following individuals:

Jay Johnson

Weyerhaeuser Corp.

Jerome Saeman

Energy Research Center

University of Wisconsin

iv
OTA Wood Use: U.S. Competitiveness and Technology Project Staff

Lionel S. Johns, Assistant Director, OTA

Energy, Materials, and International Security Division

Audrey Buyrn, Industry, Technology, and Employment Program Manager

James W, Curlin, Project Director

Julie Fox Gorte, Assistant Project Director

W. Wendell Fletcher Kathryn Hutcherson Robie

Nicholas A. Sundt* William F. Davidson*

Carol A. Drohan, Administrative Assistant

Patricia A. Canavan, Secretary

Kathleen D. Frakes, Research Assistant

Kathryn M. White, Editor

“(3TA c.ontractor
Wood Science and Technology Working Group

R. Rodney Foil

Mississippi Agricultural and Forestry

Experiment Station

Dean Einspahr

Institute of Paper Chemistry

John Haygreen

Department of Forest Products

University of Minnesota

Jay Johnson

Weyerhaeuser Corp.

T. Kent Kirk

Forest Products Laboratory

USDA Forest Service

John Koning

Forest Products Laboratory

USDA Forest Service

Alfred H. Nissan

Consultant

Necmi Sanyer

Forest Products Laboratory

USDA Forest Service

Vance Setterholm

Forest Products Laboratory

USDA Forest Service

Kenneth Skog

Forest Products Laboratory

USDA Forest Service

Robert N. Stone

Forest Products Laboratory

USDA Forest Service

Bruce Thoman

International Paper Co.

John White

Cooperative Forestry Staff

USDA Forest Service

Jerome Saeman

Energy Research Center

University of Wisconsin

Abstract

The role of technology in achieving self-sufficiency–and perhaps in expanding export

capacity-in wood products has received little attention. Although the United States has

immense timber resources, it has been a net importer of wood products for a number of

years, and Government projections of future wood supplies and demands indicate rising

timber prices and increased dependence on foreign supplies.

Several ways exist to avoid wood shortfalls. They include increasing timber production through intensified timber management, better utilization of wood residues, more efficient harvesting, and use of currently underutilized species. Technology can help expand

the resource base by enabling effective utilization of a wider range of wood species and

sizes and by increasing the yield of products manufactured from a given amount of wood

raw material through improved design and conservation.

The Office of Technology Assessment has assessed U.S. wood use and production at

the request of Congress. This volume reviews wood manufacturing technologies that might

be used to extend the timber resource through improved utilization and explores the

prospects for changes in the way wood products are manufactured and used.
Contents

Chapter Page

I.

II.

III.

Findings and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Characteristics of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,,. 10

Microstructure of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chemical Characteristics of Wood....,,....,.. . . . . . . . . . . . . . . . . . . . . . . . 11

Physical Characteristics of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Energy Consumption in Wood Products Manufacture . . . . . . . . . . . . . . . . . . . 13

Present and Prospective Uses of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Wood as a Fuel. .,... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Industrial Wood-Fuel Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Residential and Commercial Fuelwood Use,,..,,., . . . . . . . . . . . . . . . . . . . . 19

Secondary Fuels and Chemicals From Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Wood Technology and the Resource Base... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Research and Development on the Use of Wood . . . . . . . . . . . . . . . . . . . . . ..,, 23

Federal Government R&D Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

R&D in Academic Institutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Industrial R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Solid Wood and Panel Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Profile of the Lumber and Panel Products Industry . . . . . . . . . . . . . . . . . . . . . . . 34

Raw Materials...,.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Product Demand ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,,. 35

Industry Size and Distribution of Production . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Use of Solid Wood and Panel Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Industry Trends and Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Product Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Forest Resource Use., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Efficient End Use of Wood Products, , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Lumber Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Lumber Manufacture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Potential Improvements in Milling Efficiencies and Lumber Manufacture . . 42

Consumption and Use of Lumber Products in the United States . . . . . . . . . . 48

Plywood and Panel Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Plywood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Particleboard ,.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Structural Composite Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Fiberboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Present and Future Use and Consumption of Panel Products. . . . . . . . . . . . . 58

Wood Use in Light Frame Construction. . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Wood Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

New Uses for Solid Wood Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Composites of Wood and Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Pulp, Paper, and Fiber Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Profile of the Pulp and Paper Industry ,.... . .,...,.,,,,...,,,,, ,,.,. 68

Uses of Pulp, Paper, and Paperboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Advanced Paper Materials . . . . . . . . . . . . . . . . . . . . . . . ...,.,..,.,,,,,,,,, 71

Role of Paper and Cellulosic Materials in the U.S. Material Mix . . . . . . . . . . . 72

Competition From Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Competition From Electronic Technologies, .....,,, . . . . . . . . . . . . . . . . . . . 76

vii
Contents–continued

Page

Pulp, Paper, and Cellulose Fiber Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . 79

Mechanical Pulping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Chemical Pulping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Dissolving Pulp Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

List of Tables

Table No. Page

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22,

23.

24,

25.

26.

27.

28,

29.

30,

Taxonomy of Major Forest Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Physical Properties of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Structural Properties of Some Wood, Metals, and Masonries . . . . . . . . . . . . . . . 13

Energy Requirements for Primary Commodities . . . . . . . . . . . . . . . . . . . . . . . . 14

OTA Calculations of Wood-Fuel Removals, 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Estimated Wood Stove Shipments and Inventory . . . . . . . . . . . . . . . . . . . . . . . . . 19

Status of Selected Technological Developments in Wood Utilization . . . . . . . . . 24

Funding and Man-Year Commitments by Activities at the U.S. Forest

Service, Forest Products Laboratory, Madison, Wis.: Fiscal Year 1981 ,,...., 26

1981 Funding and Scientist-Years by Activities at the U.S. Forest

Service Experiment Stations, 1981 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Funding of Wood Utilization R&D Performed by U.S. Academic

Institutions in Fiscal Year 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Domestic Consumption of Lumber and Panel Products, 1976 . . . . . . . . . . . . . . . 37

Selected Statistics on the Lumber and Panel Products Industry, 1981 . . . . . . . . 38

Number of Primary Timber-Processing Establishments in the United States,

by Industry and Type of Organization, 1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Lumber Production by Mill Size, 1979 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Large Mills and Production by Region and Size , . . . . . . . . . . . . . . . . 38

Types of Softwood Sawmills and Their Primary Product. . . . . . . . . . . . . . . . . . . 41

Summary of Major Technologies for Improved Lumber Manufacture . . . . . . . . 44

Plywood and Panel Products Consumed in New Residential Construction

in the United States 1962-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Plywood End Uses and Their Susceptibility to Penetration by

“New’’Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Summary of Major Technologies for Plywood and

Panel Product Manufacture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .,,. 60

Benefits of Truss Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 63

Estimated North American Capacity by Grade of Top 20 Pulp, Paper, and

Paperboard Producers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

U.S. Production of Paper and Paperboard in 1981 and Projected for 1984.... 71

Uses, Grades, Production, and Consumptionof Paper Products

in the United States in 1979 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

New Information Technologies and Their Potential Impact on

Paper Construction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Major Commercial Wood-Pulping Methods, Grades of Pulp, and

End-Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Summary of Process Variables for Mechanical Pulping . . . . . . . . . . . . . . . . . . . . 83

Energy Demand Per Ton of Kraft Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Energy Consequences of Pyrolytic Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Strength Properties of Press-Dried Hardwood Paper and Conventional

Softwood Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

.

Vlll
Contents–continued

List of Figures

Figure No.. Page

I. Three Characteristic Directions of Wood That Are Influenced by

Wood Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2. U.S. Wood Energy Consumption, 1850-1980. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Estimated Wood-Fuel Consumption, 1961-81 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4. Timber Supply to and Product Output From Primary

Processing Plants, 1976 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5. Chemicals From Wood. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6. Historical Research and Development Expenditures . . . . . . . . . . . . . . . . . . . . . . . 29

7. U.S. Trade in Lumber and Panel Products, 1976. . . . . . . . . . . . . . . . . . . . . . . . . . 35

8. Flow Diagram of a Typical State-of-the-Art Small-Log Sawmill, Indicating

Process Waste Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9. Present and Predicted Materials Balance for Softwood Lumber Based on

Ovendry Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

10. The Maximum Yield of Lumber From Conventional and

Innovative Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

11. Per Capita Consumption of I.umber 1950-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

12. The Truss Frame System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

13. Flow Diagram of a Small-Log Plywood Mill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

14. Material Balance for Softwood Plywood Based on Ovendry Weight . . . . . . . . . 52

15. Materials Balance for the Manufacture of Underpayment Particleboard Based

on Ovendry Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

16. Materials Balance for the Manufacture of Structural Particleboard Based

on Ovendry Weight of Chipping and Flaking of Sound Wood . . . . . . . . . . . . . . 55

17. Idealized Typical Waferboard Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

18. Idealized Typical Oriented Strand Board Process . . . . . . . . . . . . . . . . . . . . . . . . 57

19. Historical Production of Major Panel Products, 1970-79 . . . . . . . . . . . . . . . . . . . 59

20. Offcenter, In-line Joint Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

21. Wooden I-Beam Construction, Cross-Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

22. Proportions of Woodpulp Produced by Commercial Pulping Processes . . . . . . . 80

23. Schematic Flow Diagram of Alternative Mechanical Pulping Processes . . . . . . 81

24. Wood and Energy Flows in Mechanical Pulping Mills in

Conjunction With Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

25. Material and Energy Flow into a Kraft Pulpmill . . . . . . . . . . . . . . . . . . . . . . . . . . 86

26. Overall View of Papermaking From Chemical Pulp by the Kraft

Pulping Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

ix
Findings and Conclusions
Findings and Conclusions

1. Technologies for wood use could affect future U.S. timber

requirements in two ways: 1 ) by extending the wood resource through improved product recovery and 2) by substituting wood for nonrenewable materials.

The United States currently has abundant

productive timber resources compared to those

of most other industrialized countries. However, the U.S. Department of Agriculture’s

(USDA) Forest Service forecasts possible shortfalls in the year 2030 of domestic timber species

and sizes currently used for structural materials, pulp, and paper. At the same time, the

U.S. forest products industry sees a potential

for increased export of wood products and a

more active U.S. role in world wood trade,

Technology will play a major role in both extending timber resources and developing new

and improved ways to use wood,

Il. Existing and emerging manufacturing technologies could

increase wood product yield significantly and may result in increased utilization of forest residues for industrial energy production.

Because nearly half of all industrial forest

products are lumber and structural panels, increased yield of these products alone could

have a major impact on domestic timber demand. However, increased yield of solid wood

products also could reduce the amount of waste

wood available for energy generation in lumber

mills and pulpmills, a situation that could stimulate greater use of forest residues and other

biomass in the forest products industry, Lumber

products, generally used for structural support,

are long, thin, rectangular pieces of solid wood.

Panel products often are used for structural

sheathing and generally are manufactured in

4-by 8-ft sheets usually less than 1 inch thick.

Pulp products include paper and paperboard,

films, and fabrics,

The amount of roundwood required for lumber production could be reduced 20 to 40 percent by using currently available technologies

such as Best Opening Face (BOF), saw-dry-rip

(SDR), or edge-glue and rip (EGAR), although

it will take several years to achieve even a 20-

percent reduction. Such savings would be significant, since lumber consumption of over 50

million tons in 1979 accounted for about half

of all wood products consumed.

Composites— such as parallel-laminated

veneer (PLV) and corn-ply-are probably the

most material-efficient lumber products.

They are manufactured by gluing veneers or

particles together and sawing the resulting

boards into a variety of products. Use of these

processes can increase lumber recoveries 40

to 90 percent or more. However, this technology is not yet used on a large commercial scale

(probably less than 1 percent of all lumber

products are composites]; such technology

would require new facilities entirely different

from those in conventional lumber mills. Even

though composite lumber products offer increased lumber recovery and use of lower quality wood, they are unlikely to replace conventional sawn lumber to any great extent during

the next two decades because of the large capital investment requirements, high variable

costs (e. g., glue costs), and possible problems

resulting from formaldehyde emissions from

adhesives.

Adoption of several new technologies could

increase lumber recovery of existing mills up

to 30 percent without major plant alterations.

Among these are the BOF program and the

EGAR process. BOF is a computer-assisted

method for increasing lumber volume and

grade by optimizing sawlines. Laboratory tests

and some inservice tests indicate that BOF

could increase lumber yields by more than 20

percent. EGAR is an innovative sawing-andgluing technique that reduces loss of wood in

the sawing process, can increase lumber recovery 10 to 13 percent, and permits the use of

lower quality raw material.

Product yields in the manufacture of composite wood panels are 75 to 80 percent by

weight, compared with the average current

plywood recovery of about 50 percent. Composite wood-panel products (particleboard) are

manufactured from woodchips, flakes, wafers,

or strands that are glued and formed into plywood-like sheets. Composite panels with the

strength of plywood are now being produced

3
4 ● Wood Use: U.S. Competitiveness and Technology

and eventually will substitute for plywood in

many structural uses.

Substitution of composite wood panels for

plywood already has begun, and substantial

additions to waferboard and oriented strand

board (OSB) production capacity has been completed, Composite panels will begin to replace

significant amounts of plywood in structural

use by the middle of the decade, Within 10 to

20 years, it is likely that these products will replace most construction plywood, Limits on

production of composite panels probably will

have more to do with access to investment capital in processing facilities than with institutional or technological constraints.

Increased use of improved mechanically

produced pulps can increase fiber yields from

about 50 percent to almost 95 percent, reducing wood requirements to 1.05 tons per ton

of paper. Over 75 percent of current U.S. pulp

and paper production is from the relatively

low-yielding kraft chemical pulping process.

Since about one-third of industrial roundwood

in the United States is used for pulp and paper (53.5 million tons in 1979), a significant improvement in overall fiber recovery would result if highly efficient mechanical pulping

replaced chemical pulping. For example, thermomechanical pulping (TMP)—an improved

mechanical pulping process that produces

higher quality paper than other mechanical

processes—could displace about 300 pounds of

the kraft paper currently used in each ton of

newsprint. Opportunities also may exist for reducing the amount of kraft pulp used in other

printing papers. There probably are practical

limits, however, on the extent to which mechanical pulps can substitute for chemical

pulps, because high-strength and permanently

bright papers cannot yet be manufactured from

mechanically produced pulps.

Opportunities for improved mechanical pulps

to make significant contributions to pulp consumption over the next two decades are reasonably good. Production of improved mechanical pulps already has begun and is expected

to expand.

Ill. Technology could expand the use of currently abundant

hardwood species, enabling use of wood material now

underutilized.

Over one-third of the total volume of existing U.S. timber is hardwood. Hardwood inventories are increasing at a rate over six times that

of softwoods, which have been more heavily

utilized because of their superior properties for

the manufacture of many conventional wood

products. In the Eastern United States, hardwoods comprise over 62 percent of the standing timber, yet account for only 44 percent of

the harvest. Thus, in the East, and particularly

in the South, hardwoods are a significant and

underutilized wood resource. Because of their

wood qualities, softwoods currently are preferred for manufacture of lumber, plywood,

and some types of paper, However, existing

and emerging technologies may be capable of

using hardwoods to make many products that

are now produced mostly from softwoods.

Composite lumber and particleboard,

which can be manufactured from hardwoods,

could substitute for softwood lumber and plywood. In addition, SDR technology could

enable the manufacture of high-quality sawn

lumber from underutilized and abundant hardwood species, SDR is a modification of the normal sequence of lumber processing that may

reduce defects and waste in hardwood lumber

manufacture. The SDR process maybe adopted

without major equipment changes or additions

to existing mills.

Increased use of hardwoods for pulp and

paper may be possible with the adoption of

mechanical and chemimechanical pulping

technologies. Hardwood species are used extensively for the production of newsprint and

fine printing papers. However, papers manufactured from hardwoods are weaker than

those made from softwoods, which have long

fibers; thus, their end use is limited to applications where paper strength is not of prime importance. Chemimechanical pulping (CMP),

which involves chemical treatment of wood

prior to grinding, may be able to produce

strong hardwood papers that could displace or

supplement the use of some softwood papers,
Findings and Conclusions ● 5

Press-dry papermaking technology offers

perhaps the greatest opportunity to expand

future hardwood utilization. Press drying,

which produces paper from hardwood pulp

using high pressure and high temperatures during part of the papermaking process, could

produce heavy-duty linerboard with strength

properties generally superior to those of conventional kraft linerboard. Linerboard currently uses about one-fourth of the wood pulp

produced in the United States (approximately

13 million tons/y r), and prospects are good for

increasing linerboard exports. Response to the

markets and a combination of press-dry technology and hardwood CMP in the production

of linerboard, could expand significantly the

use of several currently underutilized hardwood species. Softwood pulps also can be processed by press drying, but the principal advantage of the technology is that it enables

manufacture of high-strength papers from

hardwoods. The press-dry process was developed by the U.S. Forest Products Laboratory

(FPL) and requires further modification and

testing before it can be commercialized.

IV. Conservation of solid wood materials through increased

recycling of waste paper and improved structural design could reduce demands for wood.

Approximately one-fourth of the total paper

pulp produced in the United States annually

comes from recycled paper. Recycling presents

some opportunities for energy conservation.

The use of 14 percent recycled fiber for the

manufacture of newsprint, for example, could

reduce electricity consumption in paper making by 7 to 10 percent. Two major barriers to

increasing recycling remain, however, in the

United States: 1) used paper usually is contaminated with glue, ink, and other materials that

are expensive and difficult to remove; and 2)

the economics of waste-paper collection and

transportation make recycling generally unprofitable, except in metropolitan areas. Only

a few paper mills operate with recycled paper

alone; most often, they blend it with virgin

pulp, which lends strength to the weaker, recycled fibers. The practical upper limit for

using recycled fiber in furnished paper is about

40 percent.

Some construction techniques and designs

can reduce structural wood products requirements in residential construction by nearly

one-third. Since over 50 percent of the lumber

and panel products consumed in the United

States are used for residential and nonresidential construction or structural maintenance,

significant savings in total wood consumption

could be realized from a modest reduction in

construction wood use. Designs that rely on the

interaction of individual building components

for structural strength–e.g., truss framing, wall

and floor assemblies, and sandwich panels that

replace framing and sheathing—also conserve

wood. Penetration of these innovations into

construction markets is likely to be slow, however, due to the conservatism of building codes,

the construction industry, and home buyers.

Also, some current trends, such as the use of

wider framing lumber for increased energy

efficiency, may result in increased structural

requirements.

V. New pulping technologies could reduce energy requirements for pulp and paper making and even produce additional energy for outside sale.

An estimated one-half of the wood (both industrial roundwood and other wood) removed

from U.S. forests, over 120 million ovendried

tons, eventually is consumed for energy production. Almost two-thirds of the wood fuel

burned in 1981 was consumed by the wood

products industry. The pulp and paper sector

alone accounted for about 3 percent of total

U.S. energy consumption. As a result of this

large energy usage, pulp and paper manufacturers have become industrial leaders in energy

conservation and electric cogeneration.

Innovations could boost waste heat recovery in mechanical pulping for use in paper

drying, space heating, and water treatment.

In addition, use of pulping technologies such

as pressurized groundwood (PGW] pulping,

CMP, and chemithermomechanical pulping

(CTMP), would result in lower energy requirements than those of TMP and chemical pulping technologies.

Process improvements in chemical pulping

may allow mills to approach energy self-suf-
6 ● Wood Use: U.S. Competitiveness and Technology

ficiency. Among the strategies available to reduce energy consumption are: 1) increasing the

use of wood waste in cogeneration, 2) using

spent pulping liquor more efficiently for fuel,

and 3) recovering low-quality energy more efficiently through heat pumps and heat exchangers.

Improvements in drying technology offer

the greatest opportunities for reducing energy

consumption in lumber and panel manufacturing because about 70 percent of the average energy consumption is used in kiln operations and panel drying. Solar kilns, vacuum

kilns, and microwave drying are current options for reducing energy consumption. Improved operation of conventional steam-heated

kilns through use of sensors and computer controls also provide opportunities for reducing

energy consumption.

Improvements in residential stove and furnace design and in technologies for producing industrial wood energy could probably

raise the efficiency of direct wood-fuel combustion to 80 percent of the heat-producing

potential of the wood. Conversion from open

fireplaces to efficient wood stoves could change

wood fuel-use efficiency from negative values

(heat loss) to as high as 50 percent. Use of selfstoking furnaces, heat storage devices, and circulating systems could raise residential wooduse efficiencies to 80 percent of the fuel’s heat

potential. In larger commercial and industrial

applications, fluidized-bed burners can achieve

efficiencies of up to 80 percent, though current

efficiency averages 70 percent. Gas turbine

technologies coupled with fluidized-bed burners could efficiently cogenerate electricity if

technologies were developed to cleanse the

combustion gases.

It is feasible (but uneconomical using existing chemical technologies) to convert forest

biomass to chemical feedstocks and intermediate products that are currently extracted

from petroleum. These may be transformed

into nearly all the major industrial organic

chemicals. Optimistic projections indicate that

liquefaction, gasification, pyrolysis, and

hydrolysis of less than 60 million tons of wood

and wood residues theoretically could supply

a significant proportion of the synthetic polymers

currently consumed in the United States. However, the complex processes required for their

manufacture are uneconomic at this time. Production of ethanol and methanol from wood

and the oxygen gasification of wood could result in production of liquid fuels and syngas

for energy conversion.

VI. New wood products may serve as substitutes or complements for materials derived from nonrenewable

resources.

For example, composite materials made of

wood and fiberglass, plastics, or metal have

demonstrated superior performance in some

applications, although these composites currently account for only a small proportion of

the total wood materials used. Experiments at

FPL have demonstrated the technical feasibility of producing very stiff, high-strength paper,

which, with further development, may some

day be used for wall sheathing or modular

structural panels. Tests of paper construction

materials have yielded mixed results, and a significant amount of additional work is probably

needed before paperboard could become a

major structural material.
CHAPTER

Introduction
CHAPTER 1

Introduction —

Few materials are as widely used or as versatile as wood. For millenia, wood’s extensive

natural occurrence and its adaptability, renewability, and workability have combined to make

it a material of choice in a wide range of applications. When abundant, wood has helped

build and fuel many great civilizations. Scarcity of wood has sometimes contributed to a

civilization’s decline.

For many purposes, wood has required comparatively little alteration from its natural state,

More recently, technology has helped transform wood into an expanding variety of products bearing little resemblance to wood as it

appears in trees or is used in conventional

lumber (table 1). In addition to lumber and

firewood, products that can be made from

wood now include chemical feedstocks and

plastics, reconstituted wood-building materials,

liquid and gaseous fuels, food supplements,

and 14,000 kinds of paper,

Table 1 .—Taxonomy of Major Forest Products

Status of

Product Description Major end use

Lumber type products

Board s

a -

- 

Dimensiona lumber

Timbers

Parallel laminated

veneer (PLV)

Utility poles

Panel type products

Plywood

Hardwood

Particleboard

Medium-density

fiberboard

Semirigid insulation

board

Rigid insulation

board

Waferboard

Oriented strand

board (OSB)

Corn-Ply

1“ thick, 4“ to 16’, > 1“ wide

2“ to < 5“ thick, > 2" wide, usually 4’ to 16’

long solid wood, sometimes edge glued

5 + thick, > 4“ wide, various lengths;

solid or laminated wood

Usually same dimensions as lumber and

timbers, made from wood veneers

laminated with parallel grains

9“ to 14” diameter, 50’ to 80’

Flat panels, usually 4’ x 8’, less than 1.5”

thick, made from wood veneers laminated

with grains of adjacent veneers

perpendicular, Usually 3 to 5 plies (veneers)

Flat panels made of individual wood fibers,

usually glued together

Flat panels, less than 1.5” thick, cut to

size of 4’ x 8’, composed of very small

wood particles glued together

Same as hardboard, with extremely flat,

smooth surface and edges

Flat panels made of individual wood fibers,

usually loosely matted, fibers bonded by

interfelting

Same as semirigid insulation board

Flat plywood-like panels made with flat,

nonalined wafers or large chips of wood

glued and pressed together

Flat plywood-like panels made with aligned

strands or ribbon-shaped pieces of wood,

Sometimes crossbanded (strands in

different layers oriented perpendicular to

adjacent layers), sometimes veneered

Flat plywood-like panels or lumber-like

pieces, with particleboard cores and

wood veneer faces

M

M

M

G

M

M

M

M

M

D

D

G

G

General purpose

Structural framing

Structural framing beams, and large

supports

Structural framing and supports, Can

be used in millwork and molding

Transmission lines

also

Structural sheathing, flooring, and a variety

of semistructural uses

Floor underpayment, facing for architectural

concrete, wall linings, door inserts, stereo,

radio and TV cabinetry, and furniture

Underlay merit, furniture core

Furniture, wall siding

Insulation, cushioning

Interior walls and ceilings, exterior sheathing

Paneling, substitute for plywood in

structural use, wallboard

Same as plywood

B Same as lumber and plywood

9
10 ● Wood Use: U.S. Competitiveness and Technology

Table I.–Taxonomy of Major Forest Products (continued)

Product Description —

Paper products

Unbleached

kraft paper

Bleached

kraft paper

Newsprint and

groundwood

printing papers

Corrugating medium

Linerboard

Paperboard

Coated paper

Specialty papers

Tissue paper

Other products

Rayon

Acetate

Cellulosic films

Brown, somewhat coarse, stiff paper

manufactured primarily by the kraft sulfate

process from hardwoods and softwoods

White fine textured paper manufactured by

either the kraft sulfite process or the kraft

sulfate process from either softwoods or

hardwoods. The better papers are

provided from softwoods

Coarse textured paper of low strength and

limited durability, which tends to yellow

with age. It is manufactured from

mechanical and semimechanical (particularly

chemically treated) pulp, which uses either

hardwoods or softwoods

Coarse, low-strength paper produced

primarily from sulfite pulping of hardwoods

Stiff, durable, thick paper made primarily

from unbleached kraft paper made by the

sulfate process

Stiff paper of moderate thickness made

primarily from bleached sulfate kraft pulp

Printing papers that have been coated with

materials that improve printability and

photo reproduction

Diverse group of products ranging from

thin filter papers to stiff card stock

Thin, soft, absorbent papers manufactured

primarily from chemical groundwood pulps

Synthetic fiber produced by the viscose

process using pure cellulose produced by

the dissolving pulp process. Rayon has

properties similar to cotton

Synthetic fibers produced from dissolving

pulp-like rayon, but further chemical

treatment make them water resistant with

properties more like nylon or orlon

Film made from dissolving pulp by the

rayon and acetate processes, but

extruded as sheets of various thicknesses

Status of

lifecycle

M

M

M

M

M

M

M

M

M

M

M

D

Major end use

.

Heavy packaging, bags, and sacks

Fine writing and printing papers and

paperboard for packaging

Printing of newspaper and for other

printing uses not requiring durability

Corrugated boxes as dividers and

stiffeners between the paperboard liners

Heavy duty shipping containers and

corrugated boxes

Milk cartons, folding boxes, and individual

packaging

Magazines, annual reports, and books

Cigarettes, filter papers, bonded papers

(with cotton fibers) index cards, tags, file

folders, and postcards

Toweling, tissues, and hygenic products

Woven cloth as a cotton substitute

Woven cloth as a substitute for nylon and

other petroleum-derived synthetic fibers

Packaging (cellophane) protective

coverings, photographic applications,

transparent drafting and graphic materials

NOTE: B

SOURCE Office of Technology Assessment

Characteristics of Wood

Wood is grouped into hardwoods and soft- characteristics are significant between and

woods. Hardwoods generally are broad-leaved within species and even between pieces of

deciduous trees, while softwoods are conifers, wood from different parts of a single tree.

with needles or scalelike leaves that generally

are evergreen. Although there are broad differences in the characteristics of wood from Microstructure of Wood

hardwoods and softwoods, variations in micro- Differences in microstructure between softstructural, physical, chemical, and mechanical woods and hardwoods give the wood from
Ch. 1—Introduction ● 1 1

these species different properties, Softwoods

have fewer cell types, generally longer fibers,

thinner cell walls, and more uniform cellular

arrangements than do hardwoods. Because of

their strength, softwoods often are preferred

in structural applications. Hardwoods vary

considerably in their machining and drying

characteristics, which makes the commercial

use of hardwoods more complex, However,

grain patterns and color make them attractive

for furniture and cabinetry.

There also can be microstructural differences

within species of wood. Leaning trees contain

compression wood (softwoods) or tension

wood (hardwoods), apparently a result of the

tree’s microstructure changing to accommodate the uneven load distribution as it grows.

Fertilization, pruning, and other silvicultural*

practices also change the microstructure of

wood. These changes, currently under investigation by wood technologists, may have some

effect on the utilization of wood grown in controlled environments (the so-called plantation

wood).

Chemical Characteristics of Wood

The major chemical constituents of wood include: 1) cellulose, 2) lignin, 3) hemicellulose,

and 4) extractives. Cellulose, which comprises

approximately 50 percent of wood by weight

(ovendry), is the primary structural component.

The exceptionally strong chemical bonds within cellulose molecules give wood great strength

relative to its weight, Cellulose fibers are the

major component of paper and can be altered

chemically to produce a wide range of products such as chemicals, plastics, synthetic

fibers, and films, Lignin, which cements the

fiber together, is a complex organic chemical

the structure and properties of which are not

fully understood. Theoretically, lignin could be

converted into a number of chemicals. Currently, however, it is burned to produce energy

as a waste product from pulp and paper manufacturing, Hemicellulose is similar to cellulose in composition and function. It plays an

important role in fiber-to-fiber bonding in papermaking. Finally, several extractives are

contained in wood but do not contribute to its

strength properties,

Physical Characteristics of Wood

Physical properties of wood vary considerably, both between and within species. Some

of the more important physical properties of

wood are: 1) density (or specific gravity); 2) mechanical properties (strength and stiffness are

most important); 3) shrinking and swelling due

to changes in moisture content; 4) thermal

properties; 5) electrical properties; 6) machining or working qualities; 7) susceptibility to

decay; 8) degree of resistance to chemicals;

9) combustibility; 10) weathering; and 11) appearance, such as grain, texture, and sheen,

The range of values for some of these properties and their importance is shown in table 2.

Density (mass per unit volume] is generally

a good indicator for other properties (including

mechanical, thermal, and electrical). Specific

gravity varies with different locations in the

tree and is influenced by silvicultural practices;

hence, it influences a tree’s other properties,

Manipulation of growth factors is one of the

few controls available to “manufacture” the

wood substance to desired properties. This

contrasts with other materials, in which many

variables can be manipulated to achieve desired properties,

Wood moisture content (the ratio of the

amount of water in the wood to its dry weight)

is another important variable. This moisture,

bound in the cell walls, influences wood properties. Stiffness and strength decrease, and

thermal and electrical conductivity increase,

as moisture content increases, The moisture

content of living trees usually is above 50 percent but varies considerably by species, time

of year, and associated weather conditions.

Once felled, however, the wood dries and tends

toward an equilibrium moisture content (EMC)

corresponding to prevailing relative humidity

and temperature conditions. Air or kiln drying is used to reduce the moisture content of
12 ● Wood Use: U.S. Competitiveness and Technology

Table 2.— Physical Properties of Wood

Property Range or average Importance

Density (specific gravity) 20-45 lb/ft3

(0.3 to 0.7)

Shrinkage and swelling Hardwood: 10-19 percent

by volume

Softwood: 7-14 percent

by volume

Thermal properties

Electrical properties

Decay and chemical

resistance

Combustibility

Working qualities

Weathering

Appearance

Resistance: R= 1.25

[ft 2 h“ F/Btu/in]

Diffusivity: D=O.25 x 10-3

(in2/s)

Dielectric constant: 2-5

Resistivity: 1010 to 1013 ohm-m

(103 to 104 when saturated)

—

Density can affect the ability of wood to hold coatings such

as paint, stain, and adhesives. It affects the machinability

and other working qualities and the weight and ease of

handling the products.

Shrinkage upon drying can result in warping, crooking, and

bowing in lumber. Some woods have a greater tendency

toward internal stresses caused by shrinkage, which may

make them less suitable for lumber or may require

special treatment to avoid deformities. Shrinkage along

the grain is only 10 percent of shrinkage across the

grain.

Wood is a good thermal and electrical insulator. Because its

thermal conductivity is a fraction of that of most metals,

wood tends to gain heat slowly from its surroundings.

Wood is a poor electrical conductor, though its conductivity

increases with increasing moisture content.

Different species vary in resistance to decay and chemicals.

Wood deteriorates more rapidly in warm humid

environments than in other conditions. It is often used in

chemical processing operations where exposure to mild

acids and acidic salt solutions would corrode ordinary

steel or cast iron.

Two important aspects of wood combustibility are flame

spread and char development. Rate of charring into large

wood members is very slow; hence, strength is retained

for a long time in a fire situation.

Working qualities refers to the ease and quality of planing,

shaping, turning, mortising, sanding, steam bending, and

nail and screw splitting. They affect appearance, useful

life, and range of use of wood products.

Weathering causes boards to warp, pull out fasteners, check

or split, and turn gray. Sometimes weathered appearance

is desirable for decorative use.

Color, grain, texture, sheen, and surface roughness affect

the appearance of wood. Fine furniture woods require

special characteristics, as do woods used for paneling

and cabinetry. The appearance of structural material is

less important.

SOURCE Adapted from U S Department of Agriculture, Forest Service, Forest Products Laboratory, Wood Handbook Wood as an Engineering Material (Washington,

D C U S Government Printing Off Ice, 1974)

green lumber to approach the EMC to meet the

end-use requirement.

In contrast to most other structural materials

such as ceramics, concrete, and metals, which

have the same properties in all directions,

wood is naturally anisotropic, having different

mechanical and physical properties along its

three dimensions. The three mutually perpendicular, characteristic dimensions of wood are

called: longitudinal (along the grain), radial

(across the grain, out from the center), and tangential (across the grain, tangent to the annual

rings) (fig. 1). Stiffness and strength, as well as

other properties, vary considerably in the three

directions.

Strength, particularly along the grain, is one

of the most important mechanical properties

of wood. Wood’s strength is compared on a

strength-to-weight basis with other materials

in table 3.

During use, wood is subjected to a number

of different loading modes including bending,

compression, shear, and tension. Most impor-
Ch. I—Introduction ● 1 3

Figure 1 .—Three Characteristic Directions of Wood

That Are Influenced by Wood Properties

tantly, wood is a very efficient material for

bending applications, and designers can compensate for its relatively low shear strength parallel to the grain by making long, slender structural members that stand up well to bending. *

In addition, because its compression strength

is relatively high, wood is an excellent material for columns. Its inherent strength is less

important in the design of columnar supports

than its geometry and stiffness. Clear wood

also has high tensile strength. As a result,

higher grade (clear] material is used in tension

members of trusses or in the outer layers of

laminated beams.

Energy Consumption in

Wood Products Manufacture

The amount of energy required to produce

construction materials and paper from wood

generally is less than that required for producing products from metals, plastics, or masonry

on a weight basis (table 4). Production of paper,

for example, uses less than half the energy per

ton than does the production of plastics and

less than 10 percent as much as the production of aluminum foil for packaging. Thus,

wood, being a renewable resource, could substitute for other materials that require large

amounts of energy for their manufacture.

Table 3.—Structural Properties of Some Wood, Metals, and Masonries
14 . Wood Use: U.S. Competitiveness and Technology

Table 4.—Energy Requirements for Primary Commodities (million Btu (oil-equivalent)/ton))

Available residue

Commodity Extraction Processing Transport energy N e t

a total

Softwood lumber . . . . . . . . . . . . . . . . . 0.943 4.846 1.966 8.313 2.909

Softwood sheathing plywood . . . . . . 0.747 6.871 2.081 3.697 6.002

Structural flakeboard . . . . . . . . . . . . . 0.956 7.511 1.314 8.616 2,270

Underpayment particleboard. . . . . . . . 4.6172b

8.101 1.198 1.529 12.387

Concrete . . . . . . . . . . . . . . . . . . . . . . . . 0.52 7.60 0.40 — 8.52

Concrete block . . . . . . . . . . . . . . . . . . 0.52 7.60 0.65 — 8.77

Clay brick . . . . . . . . . . . . . . . . . . . . . . . 0.57 7.73 0.76 — 9,06

Steel studs . . . . . . . . . . . . . . . . . . . . . . 2.45 46.20 1.67 — 50.32

Steel joists . . . . . . . . . . . . . . . . . . . . . . 2.45 46.20 1.67 — 50.32

Aluminum siding . . . . . . . . . . . . . ....26.80 172.00 1.67 — 200.47

Present and Prospective Uses of Wood

Domestic production of wood has increased

by about one-third since 1950. Much of the

growth in demand for wood has been in highvalue wood products such as lumber, plywood

and veneer, and pulp, while the declines have

been in lower value products, such as railroad

ties and mine timbers. Wood is used for a variety of purposes, including shelter and other

construction, communication, packaging, information storage, energy, textiles, and chemicals.

The chemical constituents of wood, primarily carbon and hydrogen, may be converted to

forms that can be used to manufacture a wide

range of products currently derived from petroleum—although few now are so used, Chemicals recovered from wood through pulping are

used in turpentine, rosins, pine oils, furfural,

and other commonly used chemical products.

Lignin, although currently burned as a waste

product to produce energy within pulpmills,

shows promise as an adhesive, dispersing

agent, binder, and source of vanillin and

dimethyl sulfoxide (DMSO). Rayon, cellulose

acetate, and cellulose esters, manufactured

from woodpulp, maybe used for cloth, packaging films, and explosives. Sawdust and wood

flour are used as cattle feed and as bulking

agents in human food.

As an energy source, wood’s historical importance is difficult to overstate. Until 1870,

wood was the primary fuel for both industrial

and residential heating in the United States. i

Even in 1940, when coal had long supplanted

wood as a residential heating fuel, more households were heated with wood than with gas,

electricity, and oil combined. The recent resurgence of wood in home heating—brought about

by the rising costs and potential shortages in

other energy sources—has both stimulated and

been stimulated by technological innovations

in wood-burning stoves and other devices

adapted to home heating.

The forest products industry itself has become an industrial leader in the use of wood

as an alternative energy source. Roughly half

of the energy needs of the industry are produced from wood residues and byproducts. In

some cases, mills have become virtually energy

self-sufficient. In addition, a few wood-fueled

central electric-generating stations of modest

size have been constructed by utility companies. Gasification technologies offer potential for converting wood into energy products

that are easily transported and may be used

in conventional gas combustion equipment.

Wood may also be converted to liquid fuels,

such as ethanol and methanol. In the event of

I U. S. Department of Commerce, Bureau of the Census, Historical Statistics of the United States: Colonial Times to 1970

(Washington, D. C.: U.S. Government Printing Office, 1975), pp.

587-588.
an oil supply interruption or larger increases

in the price of petroleum, wood could back up

domestic supplies of coal and other fossil fuels.

Wood has been the paper industry’s major

source of raw material for well over a century.

Paper may also be manufactured from a variety of natural cellulose materials, including cotton, bagasse, and other agricultural crops, and

from recycled waste paper, By removing lignin

and other extractives and separating the strong

individual wood fibers through chemical or

mechanical processes, paper may be formed

into a variety of products, ranging from tissues

and newsprint to construction board.

Some of the oldest and still major uses of

wood are framing, sheathing, cabinetry, and

a variety of semistructural and decorative purposes in construction. The most notable new

developments in wood utilization involve reducing wood to smaller integral components,

such as chips, strands, flakes, wafers, or fibers

and reconstituting them into products with performance characteristics different and frequently superior to those made from solid natural wood. Recent developments include

waferboard and oriented-strand board (OSB)

made from a variety of species into composites

that can substitute for conventional plywood.

Modern materials science also has made it

possible to combine different materials in a

way that can produce composite products with

performance characteristics superior to those

of either of the parent materials, Wood and

metal have been laminated to provide not only

a more durable finished furniture panel, but

also one that resists cigarette burns by dispersing heat through metal foils. Composite panels

faced with plastics are widely used for countertops, desktops, and tabletops. Plastic-impregnated papers are used for various types of

packages that must resist or contain liquids.

In the future, wood maybe combined in very

different ways at the fiber level to produce entirely new materials. For example, wood materials could be extruded, molded, and formed

into complex shapes by combining wood fibers

with binders, adhesives, and resins. Wood also

may be combined with other fibrous materials

such as fiberglass or graphite to produce new

high-strength, lightweight materials with special properties.

Wood as a Fuel

This section updates information on wood

energy use and summarizes several important

aspects of wood energy explored in detail in

a 1980 OTA report, Energy From Biological

Processes. 2

The rapid growth in coal and petroleum as

energy sources since 1870 resulted in a rapid

decline of wood’s contribution to total energy

use. Since the 1973 oil embargo, wood energy

use has grown rapidly, so that it again is the

largest use for wood by volume (fig. 2).

(government Printing office, 1980).

Ch. 1—Introduction ● 1 5

Figure 2.– U.S. Wood Energy Consumption, 1850-1980

3.0

2.5

2,0

1.5

1.0

Year

SOURCE Charles E Hewett, et al“Wood Energy in the Untted States, ” Annual

Rewew of Energy, Jack M Hollander (ed ) (Palo Alto, Cal if Annual

Reviews, tnc ), 1981
76 ● Wood Use: U.S. Competitiveness and Technology

Wood-fuel consumption totaled 2,2 quadrillion Btu (2.2 Quads) in 19803—about 3 percent

of U.S. energy use (74 Quads).4 The forest products industry accounted for 63 percent of 1980

wood energy use.5 Nearly all the remaining

wood energy consumption was for residential

home heating (fig. 3).

OTA estimates that energy accounted for

about 55 percent of the wood removed from

U.S. lands in 1980, the first year for which comprehensive survey data is available (table 5). A

1981, op. cit.

partial explanation for the high proportion of

fuelwood compared with other wood used in

1980 is that demand for other forest products

was low due to recession. However, use of

wood as a fuel has increased rapidly since the

1%0’s, even during periods when demand for

forest products was high.

The potential exists for significantly greater

wood energy production. OTA’s Energy From

Biological processes assessment concluded

that wood has the greatest potential to contribute to the Nation’s energy supply among alternative biomass energy sources. The study

found that 4 Quads/yr of wood energy could

be produced from wood by the year 2000 without significant Government action. With incentives and improved forest management, as

much as 10 Quads/yr could be produced. Much

Figure 3.— Estimated Wood-Fuel Consumption, 1961-81

11
Ch.1—Introduction ● 17

of this amount could be produced from byproducts of wood processing, logging residues, and

woody biomass removed during thinning of

timber stands, stand conversions, and other

managerncnt activities.6

Industrial Wood-Fuel Use

The forest products industry consumed 81

mill ion ovendry tons (81 million cords) of wood

in 1981. Industrial wood energy consumption

totaled 1.4 Quads of wood fuel, of which about

1.0 Quad was consumed by the energy-intensive pulp and paper industry and the remainder by the solid-wood-products sector. The

pulp and paper industry now derives about half

of its energy needs from wood fuels and lignin

byproducts produced during pulping,7 An estimated 73 percent of the solid-wood-products

industry energy needs were supplied from

wood in 1981, up from 69 percent in 1978.8

Most wood fuels used by the industry come

from wood residues and processing wastes,

rather than from trees specifically harvested

for energy use, However, some firms now harvest wood for energy use, and some residues

are traded among businesses within the industry as a marketable commodity.

Continued increases in wood-fuel use by the

forest products industry are probable but will

grow more slowly in the future. The industry

now uses over 96 percent of the woody raw materials that enter mills for either products or

energy (fig. 4). Opportunities to increase wood

energy further may depend on: 1) increased recovery of woody materials at harvest, and

2) capital investment in more energy-efficient

manufacturing processes.
18 ● Wood Use: U.S. Competitiveness and Technology

Figure 4.—Timber Supply to and Product Output From Primary Processing Plants, 1976 (million cubic feet)

Supply to primary

processing plants

Domestic roundwood 12.815

hardwoods 3,297 ●

softwoods 9,518

Imported roundwood

+

100

and chips

SOURCE: T. Ellis and C. D Risbrudt. Unpublished manuscript
Ch. 1—/ntroduction ● 1 9

Over the long term, as new facilities and

technologies designed for energy conservation

gradually are introduced, it is possible that

some forest product firms will produce more

energy than they consume, thus becoming net

energy producers. The pulp and paper industry already is a leader in cogeneration—the

simultaneous generation of useful heat and

electricity. The industry has the largest number of cogeneration facilities among U.S. industries and currently accounts for 29 percent

of the U.S. cogeneration capacity, ranking second to the primary-metals industry in cogenerated electrical power, g At one Maine pulp

and paper mill, total self-sufficiency in electricity reportedly has been achieved through a

newly constructed biomass powerplant and

company-operated hydroelectric stations. Surplus power is sold to a local utility.10

Residential and Commercial Fuelwood Use

The U.S. Department of Energy (DOE) estimates that about 48,2 million ovendry tons

(48.2 million cords) of wood was consumed in

residential heating in 1981.11 Residential fuelwood consumption has at least doubled since

the 1973 oil embargo, according to the DOE

survey. Other indications, such as a fourfold

increase in the use of wood stoves (from 2.6

million in 1973 to nearly 11 million in 1981),

also suggest rapid growth in residential fuelwood use12 (table 6).

Home fuelwood use may continue to increase, although probably not as rapidly as in

the 1970’s. Factors that will affect home fuelwood use include: 1) price and availability of

wood relative to alternative fuels, 2) proximity

of fuelwood users to wood supplies, 3) homeowner willingness to cut and transport fuelwood and maintain wood-burning stoves and

furnaces, and 4] introduction of technologically

superior wood-burning stoves and furnaces

Table 6.—Estimated Wood Stove Shipments and

Inventory (thousands)

Wood stove

Year shipments

1970 ... . . . . 224

1971 . . . . . . . 220

1972 ... 225

1973 ... . 235

1974 ... . 474

1975 ... . . 853

1976 . . 835

1977 . . . . . . 1,302

1978 . . . 1,681

1979 ... . . 2,116

1980 . . . 2,116

Wood stove

imports

NA

NA

20

20

80

280

200

240

380

437

437

Wood stove

inventory

3,079

2,866

2,751

2,630

2,744

3,295

3,850

4,807

6,088

7,868

9,531

1981 . 2,116 437 10,960

SOURCE U S Department of Energy Estfrnafes of U S Wood Energy Consurnpt(on From 1949 to 1981 (Washington, D C Department of Energy 1982)

that burn wood more efficiently or conveniently.

Commercial sector (nonforest products businesses) wood-fuel use also is increasing, although currently it comprises less than 1 percent of total wood-fuel consumption. In many

areas, market prices for wood fuel currently

are competitive with fuel prices for oil, natural gas, and coal. Commercial wood-fuel use

may continue to grow, especially in areas like

the South, which have abundant wood supplies. Some States actively encourage commercial use of wood fuels. The Georgia Forestry

Commission, for example, finances wood-fuel

demonstration projects in hospitals, schools,

and other public institutions.13

In a few instances, public utilities have established wood-fueled central electric-generating

stations, as in Burlington, Vt., and Eugene,

Oreg. Limitations on wood-fuel generating stations include large capital costs and difficulties

in assuring wood supplies from timbersheds

at economic transportation distances from

plants.

Secondary Fuels and Chemicals From Wood

Almost all wood fuels are directly burned.

A variety of long-established and emerging
20 . Wood Use: U.S. Competitiveness and Technology

technologies can process wood and woodbased residues into “secondary fuels” (gas, liquid, and solid). Similar technologies and processes can be used to produce chemical feedstocks for the manufacture of a high proportion

of chemicals, plastics, and other products now

produced from petroleum (fig. 5).

Bioconversion processes such as saccharification, fermentation, and gasification were

used to produce fuels and/or chemicals commercially on a minor scale during both World

War I and World War II, but they were not able

to compete with petroleum fuels and petrochemicals in peacetime,14 Recent developments

have focused renewed attention on production

of secondary fuels and chemicals from wood.

The technologies for conversion of wood and

other forms of biomass to energy and chemicals are discussed fully in OTA’s Energy From

Biological Processes report. 15

The potential for wood to be used as an alcohol fuel is discussed in DOE’s Alcohol Fuels

Policy Review.18 If used on a widespread basis,

methanol and ethanol could offset somewhat

U.S. gasoline consumption (about 101 billion

— ... -

Iq’rhe history of wood chemical and secondary fuel use through

World War II is discussed in Egon Glesinger, The Corning Age

of Wood (New York: Simon & S[;huster, 1949). Another book by

Glesinger, Nazis in the Woodpile: Hit~er’s Plot fi)r Essential Ra~%’

Material (Indianapolis; New York: Bobbs-Merril, 1942) discusses

the military and strategic importance of wood as a fuel and chemical to the Third Reich,

IsEnergy From Biological Processes, vol. II: Technical and

Environmental Analyses (Washington, D. C.: office of Technology Assessment, 1980),

ISU,S, Department of Energy, Report of the Alcohol Fue/s polic~ Review (Washington, D. C.: U.S. Government Printing Office, 1979].

gal in 1981).17 However, there are economic difficulties in commercializing processes to convert woody biomass to alcohol.

Wood currently is used to produce silvichemicals valued at over $5OO million per year.

Silvichemicals include naval stores (oleoresins,

tall oil, turpentine, rosins, and the like) and

chemicals derived from pulping byproducts,

such as lignin products, vanillin, DMSO, and

a variety of other useful substances,

Use of wood as a substitute for petroleum

feedstocks is technically possible but will depend on the price of petroleum and coal (which

can also be used as a petrochemical substitute)

and capital expenditures for new plant construction. Coal is widely viewed by the chemical industry as a more likely short-term substitute for petroleum feedstocks than wood.

Nonetheless, evolutionary growth in wood

chemical use is probable—especially when

wood can be used in less highly processed

forms or to produce chemicals not readily

derived from coal or petroleum.

Lignin chemistry is one promising area of research. 18 Lignin has a complex structure that

makes it difficult to process, but, left intact, it

can be used in plastics, adhesives, and various

other compounds, About 3 percent of the lignin

byproducts produced during pulping are recovered for production of chemicals; the rest is

burned for energy.

17Figure derived from Monthly Energy Review: November

1982, op. cit., p. 36.

‘BHenry J. Bungay, “Biomass Refining, ” Science, vol. 218, Nov.

12, 1982, p. 643.

Wood Technology and the

While an extraordinary range of wood prod- of the

Resource Base

national materials mix, economics and

ucts exists, they must compete with other ma- market forces generally determine which materials for their share of an often highly spe- terial is predominantly used for any specific

cialized market. Just as wood can be substituted purpose, But other factors, including existing

for many other materials, those materials can plant equipment and capital investment,

substitute for wood in some applications, with energy consumption, raw material availability

little change in product performance. In terms and security of supply, and institutional
Ch. /—lntroduct/on ● 21

1 Separation via I

Wood

- 1

t

Organic compounds

- Methane
22 . Wood Use: U.S. Competitiveness and Technology

considerations—government policies, industry

structure, and societal customs, practices, and

preferences—also play a role.

Recently, the forest products industry has experienced changes in portions of its traditional

market shares. In the highly competitive market for residential building materials, which

constitutes the largest single market for forest

products, wood has retained its dominance but

lost portions of its markets in several areas

such as flooring, siding, and furniture, At the

same time, a variety of new building materials

made from wood are available that could help

retain current markets or expand into other

areas in time,

Even within the family of wood products,

substitution takes place: plywood has replaced

lumber for many uses, and now particleboard

challenges plywood in the market for structural

panels. In some cases, composite materials

have enhanced wood’s competitiveness by permitting it to enter new markets and helping to

retain portions of markets that otherwise might

be lost. A salient example of the former is the

plastic-coated boxboard that has virtually replaced half-gallon milk containers made of

glass.

At one time, other biomass materials (primarily cotton) provided nearly all feedstocks

for plastics manufacture. By 1960, fossil fuels

accounted for 90 percent of plastic feedstocks,

even though the volume of wood feedstocks remained about the same. Uncertainties about

petroleum prices and supplies have led to some

recent, though modest, increases in woodderived feedstocks. In addition, petroleumderived plastics have competed successfully for

many specialized markets formerly dominated

by paper.

Although wood is a renewable resource, in

contrast to metals or fossil fuels for which a

fixed amount is available, the possibility of a

timber famine in the United States as a result

of the scarcity of softwood sawtimber has been

raised repeatedly for more than a century. Softwoods have been used more heavily than hardwoods because of their wood properties and

the fact that they tend to have most of the

usable wood in a well-formed trunk. As a result, softwoods are growing scarcer relative to

many hardwoods, which remain largely underutilized. Moreover, over the past century, the

real (deflated) price of softwood sawtimber has

increased steadily.

The United States has a large inventory of

both softwood and hardwood species, Growth,

on a nationwide basis, still is greater than annual harvest for both types of wood, although

the margin of annual growth over harvest is

much narrower for softwoods. Capacity of the

Nation’s forests to provide increasing amounts

of wood maybe limited, however, and technologies for improving the efficiency of wood utilization could help extend the timber resource

by offsetting increases in demand. Technology

could increase utilization by: 1) increasing the

proportion of products recovered from roundwood, or wood raw material, in primary processing; 2) expanding the ability to utilize hardwood species and defective material; and

3) increasing the efficient use of manufactured

wood products,

The United States has harvested approximately 12 billion cubic feet (ft3

) of roundwood

annually for decades, In recent years, the proportion of this harvest that has been wasted has

dropped dramatically, In 1976, less than 4 percent of the roundwood entering primary processing was wasted, although that portion still

represented 10 million tons. Because many residues from one phase of the manufacturing

process may be used as raw material for other

uses (fig. 4), an increase in the product recovery

at one point in the manufacturing process may

reduce the amount of residue available to produce other products or energy. While there are

significant opportunities for technology to

change the products manufactured from a specific quantity of wood, there appears to be little chance to increase the efficiency of wood

utilization in primary processing as a whole—

with the exception of some pulping technologies that provide higher fiber recovery.

On the other hand, technology has already

significantly affected the ability to use a wider

variety of wood species and materials formerly
Ch. 1—Introduction ● 2 3

considered worthless. The introduction of

panel products and hardboard opened avenues

for wood from limbs, branches, treetops, roots,

hardwoods, and even dead or defective wood

and bark. New technologies for paper manufacture offer enormous potential for using

hardwoods to produce strong papers for packaging and communication, Even in lumber and

plywood manufacture, which still depend on

wood cut from the trunk of the tree, the ability

to utilize smaller logs has expanded significantly. Possibilities also exist for increased use

of hardwoods. Regardless of future levels of demand, wood-utilization technology has the potential to ease pressures on the timber resource

base (table 7).

Significant

efficient end

The future

efficiency in

on research

opportunities also exist for more

use, particularly in construction.

It maybe possible to reduce the amount of lumber and panel products used (through improved integrated structural design) without

adversely affecting the quality and strength of

the structure. Present commercial techniques

could reduce wood consumption in framing by

nearly one-third, for example.

Recycling technologies also may extend the

timber resource base. Recycled wastepaper can

reduce not only the amount of virgin wood fiber needed for pulp and paper manufacturing,

but also the amount of energy consumed in the

pulping process. Little solid wood is reused

currently, but with appropriate designs and

new methods of fastening, it also might be

recycled.

Research and Development on the Use of Wood

uses of wood and the degree of

wood utilization largely depend

and development (R&D). Three

major institutional groups in the United States

are involved in R&D on the use of wood: 1) the

Federal Government, which funds as well as

performs R&D; 2) the forest industry, which is

instrumental in developing products and improving manufacturing processes; and 3) academic institutions that conduct training and

basic research. Each plays an important role

in the activities that lead to the invention, development, and eventual commercialization of

wood products and processes.

The relative proportions of industry and Government funding for all R&D in the United

States have shifted in the past 30 years. In the

1950’s and 1960’s, the Federal Government was

the major funding source for R&D, but the gap

between industrial contributions and Government funding began to narrow in the early

1970’s, Industry outspent the Government for

the first time in 1980. The National Science

Foundation (NSF) estimates that over $69 billion was expended for all R&D in the United

States in 1981. Forty-nine percent of the expenditures were made by industry, while 47

percent came from Federal agencies. The remaining 4 percent originated from foundations

and other private sources.

Current trends suggest that industry funding

as a percentage of total funding will continue

to advance, while the Federal sector’s contribution will decline.19 The funding structure for

research alone (excluding the development

function) is the reverse, however. In 1981, over

53 percent of the expenditures for basic and

applied research were derived from the Federal Government, while industry contributed

approximately 37 percent. z” The private sector

actually performed more of the total R&D undertaken in the United States than it funded,

because some private research was Government supported. In 1981, 71.2 percent of the

R&D (measured by dollars expended) was performed by industry. The Federal Government

19J. Eluga, Probable l.eLels of R&D Expenditures in 1982: Forecast and Anal~’sis (Columbus, Ohio: 13attelle Columbus Laboratories, 1981), p. 2.

ZONationa] Sclerlce Board, Science indicators 1980 (Washington, D. C.: .National Science Foundation, 1981), p, 253,

, ~~• 1 - r
Table 7.—Status of Selected Technological Developments in Wood Utilization

. .

Pulp and paper industry:

Pressurized groundwood

pulping (PGW)

Chemithermomechanical pulping

(CTMP)

Hardwood chemimechanical

pulping (CMP)

Press drying paper

Pyrolytic recovery

Organosolv pulping

Oxygen pulping

Solid wood products:

Best opening face

Saw-dry-rip

Edge glue and rip

Parallel laminated veneer

Rationale for or advantage of technology

——.

End-use product Status of commercialization Wood type

Reduced energy requirements and higher

quality paper in comparison with traditional

groundwood pulping processes; less kraft

pulp needed for mixing

Reduced energy requirements; higher quality

paper than in traditional mechanical pulping

technologies because long fibers are left

relatively intact; less kraft pulp needed for

mixing

Permits utilization of low-value hardwoods

such as red oak and poplar; reduced energy

consumption in comparison with other

mechanical techniques; less kraft pulp

needed for mixing

Permits utilization of hardwoods in production of linerboard that is superior in quality

to conventionally dried softwood kraft paper,

except in tear strength; reduced energy requirements and chemical processing needs

Reduced energy requirements in recovering

puIping chemicals

Reduced energy requirements; expanded

hardwood utilization

Oxidation of pulping liquors reduces need

for bleaching chemicals and facilities; may

reduce need-for water polIution control expenditures due to less chlorine in bleaching

Higher lumber recovery factor; permits

product yield improvements of 4 to 21 0

/0

Higher lumber recovery reduces defects in

product by 19 to 87°/0

Higher recovery of product, higher lumber

quality

Permits higher recovery of lumber from

logs, improves lumber quality; faster

processing at the mill

Newsprint, printing

papers

News print

pages

Newsprint

papers

Linerboard

, printing

printing

Process efficiency

Process efficiency

Process efficiency

Lumber uses

Lumber uses

Lumber uses

Lumber and timber

uses

Five mills worldwide as of 1980; Softwoods

15 mills ordered (4 in U.S.); rapid

growth expected

Installed at some thermomechanical pulpmills

Two small mills in U. S.; rapid

expansion possible

Feasible, but commercial-scale

facility has yet to be developed

Demonstrated

Yet to be demonstrated;

possible in next two decades

Yet to be demonstrated;

possible in next two decades

Mill-tested but not widely used

Used by some mills, but not

widely accepted

None

Some manufacturing currently

in production

Softwoods

Hardwoods

Hardwoods

Any

Hardwoods or

softwood

Primarily

softwoods

Hardwoods

and softwoods

Hardwoods

and softwoods

Hardwoods

and softwoods
.

Ch. 1 —Introduction ● 25

I In

(u

E

o-1

Q

I

c

o

0

c

u

o

0

3

.
26 ● Wood Use: U.S. Competitiveness and Technology

conducted 13 percent; universities and colleges, 12 percent; and the balance was performed by miscellaneous nonprofit organizations.

Within the forest products sector, the structure of R&D funding is obscured by the lack

of reliable and sufficiently detailed information

on Government and industry outlays for woodutilization R&D. NSF reports an estimated aggregate expenditure in 1979 of $148 million for

lumber and wood products R&D and $454 million for pulp and paper products R&D, but does

not provide a breakdown of funding by contributor. 21 Funding levels for R&D within the

forest products sector remained about the same

for 1977 through 1979, when measured in constant dollars. Between 1970 and 1980, R&D expenditures for lumber and wood products grew

approximately 62 percent, and pulp and paper

R&D increased 70 percent, when measured in

actual dollars.

occurred in the

tion during the

211t)id., p. 279.

However, little real growth

R&D budget because of inflapast decade.

Federal Government R&D Activities

Wood-utilization research conducted by the

Federal Government is concentrated in the Forest Service of the U.S. Department of Agriculture (USDA), In fiscal year 1981, the Forest

Service funded over $16.8 million of in-house

wood science and utilization research, about

72 percent of which was performed at the Forest Products Laboratory (FPL) in Madison, Wis.

The balance was conducted at the regional Forest Experiment Stations and at various research centers throughout the United States,

(University research funded by the Forest Service is discussed in a following section,) The

Forest Service tends to concentrate its in-house

wood science and utilization research on projects that generally are regarded as beneficial

to the United States—i.e., that are long-term,

high-risk, and therefore unlikely to be undertaken by the private sector,

FPL’s fiscal year 1981 R&D program included 18 activities involving approximately 97

scientist-years of effort, funded for $12,1 million (table 8). Its fiscal year 1982 budget was

targeted at $13.7 million to support an effort

of 104 scientist-years. The laboratory’s research

efforts are centered on the protection of wood

Table 8.—Funding and Man-Year Commitments by Activities at the U.S. Forest Service,

Forest Products Laboratory, Madison, Wis.: Fiscal Year 1981

Funds ScientistActivity (thousand dollars) Percent years —

Protection of wood in adverse environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 1,178.5

Engineered wood structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,149.1

Wood fiber products and processing development . . . . . . . . . . . . . . . . . . . . . . . . . . . 942.9

Engineering properties of wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888.3

Improved chemical utilization of wood ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.1

Structural composite products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 840.5

National timber and wood products requirements and utilization economics . . . 822.7

Improved adhesive systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791.0

High-yield, nonpolluting pulping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 758.0

Quality and yield improvement in wood processing . . . . . . . . . . . . . . . . . . . . . . 690.0

Criteria for fiber-product design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . 641.0

Microbial technology in wood utilization. ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.0

Improvements in drying technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.7

Fire-design engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371.0

Engineering design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370.0

Corrugated-package engineering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341.5

Center for anatomy research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.0

Pioneering research unit in descriptive wood anatomy . . . . . . . . . . . . . . . . . . . . . . 141.0

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $12,116.3

SOURCE Cooperative Research Information Service (CRIS), U S Department of Agriculture

—

9.8

9.5

7.8

7,3

7,2

6.9

6.8

6.5

6.2

5.7

5.3

4.3

4.2

3.1

3.0

2.8

2.4

1.2

100.0

8

6

5

7

7

7

8

6

6

6

5

4

5

4

4

4

4

1

97
Ch. 1—Introduction ● 2 7

from decay and insects and on the engineering of structural wood products, wood fiber

products, and manufacturing processes. Approximately 35 percent of FPL’s budget is used

for fundamental research—e.g., properties and

anatomy of wood—and 65 percent is used for

applied research. The level of research effort

has been approximately the same since 1978,

based on constant dollars expended. From 5

to 10 percent of the laboratory’s annual budget

is devoted to cooperative research with academic institutions.

In addition to research centered at FPL, the

Forest Service supported an R&D program of

$4.7 million and 40 scientist-years in fiscal year

1981 at the research centers of the regional forest range and experiment stations (table 9).

Most of this research centered on the utilization of hardwood species and on the economics of improving the performance of the regional wood products industries,

R&D on wood energy and wood as a substitute for petroleum products is conducted by

DOE at its national laboratories, although funding for these activities was reduced in the fiscal

year 1982 and 1983 budgets. At its peak in fiscal

year 1981, DOE spent $11 million on R&D related to wood combustion, gasification, and liquefaction. This work is funded in fiscal year

1983 at $2.2 million. Other research related to

wood science and utilization, such as research

on toxic preservatives and adhesives, may occur incidentally to the missions of other R&D

agencies, but its size in relation to the total Government effort is small.

R&D in Academic Institutions

Academic research plays a unique role in

complementing the research in wood science

and utilization undertaken by industrial and

Government laboratories. Funding for academic research in fiscal year 1981 was approximately $9.5 million (table 10). Less than onethird of the academic research budgets in 1981

came from the Federal Government; State and

industrial contributions accounted for 71,6 perTable 9.— 1981 Funding and Scientist-Years by Activities at the U.S. Forest Service Experiment Stations

Actlvity

Improving wood-resource harvesting and

utilization . . . . . . . . .

New and improved systems, methods, and

techniques for processing hardwoods ... .

Regional economics of forest resources ...

Low-grade hardwood utilization . . . . . . . . . . . . .

Timber quality and product-yield potential of

Western softwood resources ., ... ... .

Developing more productive markets and uses

for forest resources of the Central and

Southern Rocky Mountains ... . . . . .

Utilization of Southern timber. ... . .. .

Wood products research . . . . . . . . ...

Processing Southern woods . ... . ... .

Total ., . ... . ... . . . . . . .

Funds

Location (thousand dollars) Percent Man-years —

Forest Sciences

Laboratory

Missoula, Mont. $ 447,0 9.5 4.0

Carbondale, Ill, 361.0 7.7 3.0

Duluth, Minn. 512.0 10.9 4.1

Princeton, W.Va. 418.5 8.9 2.1

Pacific Northwest

Range Exp. Sta.

Portland, Oreg. 573.3 12.2 5.0

Ft. Collins, Colo. 286.8 6.1 4,0

Southern Forest

Exp. Sta.

Athens, Ga. 594.2 12.7 6,0

Southern Forest

Exp. Sta.

Athens, Ga. 500.3 10.7 6.0

Alexandria, La, 998.9 21.3 6.0

$4.692.0 100.0 ‘40.2

SOURCE Cooperatlve Research Information System (CR IS) U S Department of AgrlcuIture ‘- -
28 . Wood Use: U.S. Competitiveness and Technology

Table 10.— Funding of Wood Utilization R&D Performed by U.S. Academic Institutions in Fiscal Year 1980

Source (thousand dollars)

MclntyreActivity Stennis

Structural panels (including plywood and

composites) . . . . . . . . . . . . . . . . . . $ 278.1

Economic analysis and data/information . . . . . . 76.2

Properties and performance of wood and

wood products . . . . . . . . . . . . . . . . . . . . . 376.0

Energy and chemical production from wood. 181.3

Protection, preservatives, and coatings . . 78.8

Pulp and paper technology. . . . . . . . . . . . . . . . . . 125.6

General and miscellaneous wood utilization . . 42.6

Adhesives and bonding . . . . . . . . . . . . . . . . . . . . . 109.0

Structural design and fasteners. . . . . . . . . . . . . . 78,1

Drying and moisture characteristics ... . . . . . 119,1

Composite and laminated beams/lumber. . . . . . 54.8

Sawmill design and process technology . . . . . . 22.7

Wood anatomy and fiber quality . . . . . . . . . . . . . 40.7

Sawing and machining . . . . . . . . . . 3.2

Whole-tree chipping and chip processing . . . . 14.8

Species utilization . . . . . . . . . . . . . . . . . . . . . . 22.0

Total ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $1,623.0

Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0

Other Federal Non-Federal

$ 103.7 $1,505.1

165,5 1,076.8

80,7

257,4

94.5

68.0

47,2

38.8

52.0

46.9

5.9

23.4

0

16.7

61.2

18.6

610.4

458.4

523.5

394.8

399.2

338,1

335,9

292,0

233,6

164.0

158.5

163.0

106,1

38,4

Total Percent

$1,886.9

1,318.5

1,067.1

897.1

696.8

588.4

489.0

485.9

466.0

458,0

294,3

210.1

199.2

182.9

182.1

79.0

19.9

13,9

11,2

9.4

7,3

6.2

5.2

5.1

4.9

4.8

3.1

2.2

2.1

1,9

1.9

0.9

$1,080.4

11.4

$6,797.8

71.6

$9,492.3

100.0

100,0

cent of the total. Major emphasis was placed

on R&D related to composite structural panels

(19.9 percent), economic analysis and wood

products data (13.9 percent), and properties

and performance of wood and wood products

(11.2 percent).

Within the federally funded portion of the

academic research budget, 17 percent of the

funds originate from McIntyre-Stennis Act programs (76 Stat. 806), which are administered

by the USDA’s Cooperative State Research

Service. The Forest Service, NSF, DOE, and

other agencies provided 11 percent of the total

academic budget devoted to wood science and

utilization research in 1981. The remaining 72

percent came from State and industry sources.

While the proportions of R&D funds contributed by industry and the States are not identified by USDA in its Cooperative Research Information System (CRIS) (table 10), a recent

survey of forest-products research in the South

suggests that industry contributed approximately 15 percent of the academic research

funds in that region, with the States accountSOURCE Cooperative Research Information System (CRIS), U S Department of Agriculture

ing for 47 percent of the funds expended,22 The

remaining 38 percent was funded by various

Federal agencies. The Southern colleges and

universities included in the survey received

half (48.8 percent) of the total wood science and

utilization R&D funds provided to all U.S. academic institutions in 1981. To the extent that

the South reflects the national situation, the

States appear to be the major funding source

for wood-utilization R&D at colleges and universities.

Industrial R&D

Because of the proprietary nature of much

of the forest products industry’s R&D and the

reluctance of the private sector to disclose R&D

budgets, a detailed assessment of industrial

R&D is not possible, although the information

available suggests that major emphasis within

the industry is aimed at process improvement

rather than basic research.

ZZK. Thompson, status of Forest products Research at public

Institutions in the South (Mississippi State, Miss.; Mississippi

Forest Products Laboratory, 1982), p. 12.
Ch. 1 —Introduction ● 29

In terms of both dollars and scientist manyears allocated, the forest products industry is

the largest supporter of wood science and utilization R&D in the United States. NSF estimates that in 1979 the industry spent a total

of $148 million on lumber, wood products, and

furniture R&D, and $454 million on paper and

allied products R&D, Of the funds expended

by the pulp and paper industry, 4 percent were

for basic research, 25 percent for applied research, and 71 percent for product and process development. According to NSF, the solidwood-products manufacturers spent 68 percent

of their R&D budgets on development, 28 percent on applied research, and 4 percent on

basic research. ’s

A recent McGraw-Hill survey estimated the

pulp and paper industry’s 1980 R&D expenditures at $508 million and its 1981 expenditures

at $584 million,24 An estimated 40 percent of

the R&D funds were spent for improving existing products, 27 percent for developing new

products, and 31 percent for developing new

manufacturing processes, Industry analysts expect greater emphasis on new processes in the

future and a slight increase in emphasis on new

products by the pulp and paper industry

through 1985,

While actual-dollar R&D expenditures by the

forest products industry increased at a significant rate between 1969 and 1979 (fig. 6), funding remained nearly level, measured in constant dollars. Between 1977 and 1981, R&D

expenditures by the pulp and paper industry

(fig. 6) increased approximately 10 percent annually in actual dollars, compared with an

average annual increase of 15 percent in all industries. 25

Z~I n~ust r} Stllr] ie$ Groul), Science Resources Studies Hi.gh -

iight.s: Reaj Growth in Industrial R&D Performance Continues

in 1979 (Washington, D. C.: National Science Foundation, 1981),

NSF 81-313, p. 2,

Zq~C[)nomiCs D~partm~nt, ,?Yth Annual McGra w’-Hill .!urtreJr

of flusine.s.s Plans for Research and Development Expenditures

(New York: hlc~raw-}lil] Publications Co., 1982], p. 8.

25” A Research Spending Surge Defies Recession, ” Business

I%reek, July 5, 1982, p. 68.

Historical Research and Development

Expenditures

160

150 “

R&D expenditures by the

140 “

lumber and furniture industry

130 — /

(1972)

40 “

30

20

10 I I I I I I I 1 I I

SOURCE Economics Department, 27fh ,4rmua/ McGrawWI// Survey of Bus/ness

Hans for Rese@rch and Development Expenditures (New York McGraw

HIII Publlcatlon Co , 1982)

The manner in which the forest products industry reports R&D activities may mask the

nature of industrial R&D programs, For example, many of the large pulp and paper producers and integrated forest products firms

have extensive forest management research

programs in addition to wood-utilization R&D.

NSF, the Federal Trade Commission, and the

Securities and Exchange Commission report

aggregate R&D funding and do not report the

proportion of corporate funds devoted to forest management versus that spent on woodutilization R&D. For this reason, the R&D funding statistics quoted in this report include forest management research; therefore, the actual

amount spent on wood utilization R&D probably is less than reported.

Other industrial sectors also perform R&D

that is used by the forest products industry;

likewise, some forest products industry R&D

affects other industries. The major R&D effort

related to wood utilization is funded directly

by the forest products industry. A relatively

small proportion of the total wood-utilization

R&D effort appears to come from machinery

suppliers, coating (paints) and resin manufacturers (chemicals), and users of wood products.

It appears that most R&D performed by lumber

firms is specifically used by the lumber indus-
30 . Wood Use: U.S. Competitiveness and Technology

try, while less than 50 percent of the R&D performed by pulp and paper firms is used primarily by the industry itself.26

Compared to other manufacturing industries,

the pulp and paper sector is well below the

mean in its funding of R&D as a percentage of

sales and capital expenditures. In 1981, R&D

expenditures by the pulp and paper industry

were less than 1 percent of its sales—significantly less than the 2.5-percent average for all

manufacturing industries. 27 Electrical communications, aerospace, and the scientific instrument industries led all other manufacturing industries in 1981, Aerospace led all other

manufacturing industries, devoting over 16.2

percent of its capital expenditures to R&D,

which was 24 times more than that devoted by

the pulp and paper industry. 28

The relatively low premium put on R&D by

the forest products industry may be due to a

combination of factors: 1) the industry is

mature in the sense that wood products are

well developed and have been used in essentially the same form for a long time; 2) wood

products are not high technology and, therefore, are not likely to be subject to revolutionary

technological breakthroughs in their manufacture and use; 3) the industry is resourceoriented in that it focuses on the conversion

of timber to useful products, rather than on the

manufacture of a specific commodity that

could be made from a range of materials; and

4) forest industry management generally is promoted from within; thus, the industry’s R&D

direction generally is less exploratory and is

focused on product improvement or process

efficiency rather than on new products.

.

28 E(:onomics Department, Op. Cit., pp. 11-12.
Chapter II

Solid Wood and Panel Products
Chapter II

Solid Wood and Panel Products—

Summary and Conclusions

33
34 ● Wood Use: U.S. Competitiveness and Technology

Introduction

Panels have been replacing lumber in construction for the past three decades. Plywood

has been produced commercially in the United

States since the turn of the century, but plywood manufacture, like lumber manufacture,

relies on large-diameter, high-quality softwood

timber, which is becoming increasingly scarce.

As a result, technologies for panel manufacture

have concentrated on expanding the resource

base, Newer panels, made from wood wafers

or strands, can be made from small logs, residues, and hardwoods and can substitute for

plywood in construction applications, Two

new panel products, waferboard and oriented

strand board (OSB), already have captured

some plywood markets and are expected to

continue expanding. Most new, planned panel

manufacturing capacity in the United States

is in OSB or waferboard. Because these products can be made from hardwoods and from

lower quality softwoods than can plywood,

production facilities are located in the Great

Lakes States and Northeast, closer to construction markets and suitable wood supplies.

Advances in plywood manufacture also have

expanded small log utilization through improvements in log peeling technology. Other

changes in plywood production include increasing automation and improving drying

processes to reduce energy use, accelerate drying, and produce more stable panels.

These improvements in primary manufacturing have been aimed principally at expanding

the usable resource base: increasing the ability t o use hardwoods and a greater proportion

of the tree. Increasing the efficiency of wood

use in construction also has potential to reduce

the pressure on domestic timber resources, particularly the softwoods. Engineering analyses

have shown that many houses are overbuilt, or

capable of withstanding far greater stresses

than required by housing codes. More careful

matching of construction members—framing

and sheathing—to the engineering requirements of the structure could help reduce the

amount of wood required to build a home.

New construction technologies also have

shown some promise in reducing wood requirements. In particular, the use of factorymade wood trusses for floor, wall, ceiling, and

roof framing reduces lumber requirements

and, at the same time, speeds up housing construction and reduces labor costs. Factorymade housing components, such as wall panels

that combine framing and sheathing, also can

reduce wood waste and construction labor requirements. Construction technologies, however, are slow to change, and the impact of

these technologies on wood utilization is unlikely to be significant in the short run,

Profile of the Lumber and Panel Products Industry

As the world’s largest consumer of industrial

woodl (including pulp), the United States uses

over one-fourth of the world’s timber products,

more than half of which is lumber, plywood,

and veneer, In 1979, the United States consumed approximately 50 million air-dry tons

of lumber, 12 million tons of plywood, and 10

million tons of panel products, accounting for

nearly half the U.S. consumption of industrial

1 Industrial wood includes all commer(; ial roundwood products

eY(:ept fuelwood”

roundwood. 2 In addition, the United States produces over 20 percent of the world’s softwood

lumber, 15 percent of its hardwood lumber,

nearly 45 percent of its plywood, 1.5 percent

of its particle board, and 40 percent of its

fiberboard,’ — —2 —

U S DA Forest Service, U.S. Timber Production, Trade, Consumption, and Price Statistics, 1950-1980, Miscellaneous Publication No, 1408, 1981.

3Roger A. Sed jo and Samuel J. Radcliffe, Postwar 7“rends in

1 l,s, Forest products Trade: A Global, National, and Regional

l’iettr, Research Paper R-22 (Washington, E).(; ,: Resources For

the Future, 1980).
Ch. II—So/id Wood and Panel Products • 35

Despite its role as a major producer, the

United States is a net importer of lumber and

panel products, except particleboard, It imports nearly 35 percent of the world’s total softwood lumber imports, over 5 percent of world

hardwood lumber imports, 30 percent of world

plywood and veneer imports, and over 10 percent of world fiberboard imports (fig. 7). The

U.S. trade pattern is dominated by imports of

softwood lumber and plywood from Canada,

imports of hardwood veneer and plywood from

Asia, exports of softwood products (including

logs) from Alaska and the Pacific Northwest

to Japan, and some export of panel products

from the west coast and the South to Japan,

Europe, and Central and South America.

Raw Materials

In addition to the various timber used as raw

materials, plywood and panel products manufacture is a major consumer of adhesives. The

largest single adhesives market today is in plywood manufacture.4 Production of composite

panel products consumes significant amounts

of phenol and urea formaldehyde resins. Other

chemicals used by the industry include fire

retardants and wood preservatives. Preservatives may become even more important in the

future if wood use for foundations in housing

construction continues to expand. All of these

chemicals—adhesives, preservatives, and fire

retardants—are largely derived from petroleum.

Product Demand

Because demand for lumber and panel products is linked closely to the homebuilding in4

Peter Gwynne, “Adhesives: Bound for Boundless Growth, ”

Technolog~, January/February 1982, p. 43.

Figure 7.—

U S production (percent of world production) \

U.S. exports (percent of world exports)

U S imports (percent of world imports)

SOURCE Roger A Sedjo and Samuel J Radcllffe, Postwar Trends In U S forest Producfs Trade: A G/oba/ Natmna! and Reg/ona/ View, Resources for the Future, Research

Paper R.22, 1980
36 ● Wood Use: U.S. Competitiveness and Technology

dustry, production of lumber and panel products follows the general pattern of housing

starts. In 1976, construction-related activity accounted for three-fifths of the lumber and twothirds of the plywood consumed in the United

States. 5 New home construction is the major

market for lumber and plywood, although residential upkeep and improvement and nonresidential construction also consume significant

amounts. Periodic depressions in the housing

industry create soft markets that greatly affect

lumber, plywood, and panel demand, resulting

in mill closures and curtailments in production.

Other major uses of wood—manufacturing

and shipping—account for 18 percent of the

lumber and 10 percent of the plywood consumed in the United States. Furniture making

accounts for the bulk of the wood used in manufacturing, and pallet manufacturing is the major market for wood in shipping. A summary

of lumber and panel products use is shown in

table 11.

Industry Size and Distribution of Production

The lumber and forest products industry consists of 35,000 establishments and employs

nearly 700,000 workers, or nearly 4 percent of

those employed in U.S. manufacturing.6 Major wood products manufacturing sectors of

the lumber and wood products group employed 219,000 people in 1981 (table 12).

Although the industry is dominated by a few

large firms, some segments are made up of

small, competitive firms (table 13). The lumber

industry is the most competitive component of

the lumber and wood products sector. Of its

8,184 establishments, 80 percent employ fewer

than 21 people, ’ Over 50 percent of the U.S.

lumber output is produced by 10 percent of the

mills (table 14).

5 USDA E’orest Service, An Analysis of the 7’in]ber Situation

in the United States 1952-2030, review draft, 1980.

‘U.S. Department of Commerce, Bureau of Industrial Economics, 1982 U.S. Industrial Outlook for 200 Industries With Projections for 1986 (Washington, D. C.: U.S. Government Printing

C)ffi[;e, January 1982].

Lumber production is concentrated in the

South and the West, where most of the softwood, sawtimber growing stock is located.

While the South contains more sawmills than

the West, its mills generally are much smaller.

The West produces over two-thirds of the lumber output (table 15). Mills in the North and

East produce only 6 percent of the annual lumber output.

The plywood and panel products industries

are more concentrated than the lumber industry and have fewer mills. Their 232 softwood

veneer and plywood mills, 366 hardwood veneer and plywood mills, and 68 particleboard

mills employ about 77,OOO people,

Because construction, like lumber, depends

on high-value, large softwood logs, the South

and West are major plywood-producing regions. In 1979, the South and West produced

42 percent and nearly 47 percent, respectively,

of [J. S. plywood manufactured; the remainder

was produced in the northern Rocky Mountain

States. Plywood production has been shifting

to the South since the early 1960’s, primarily

because of its lower wood prices.

In 1979,96 percent of the panel manufacturing capacity was in plywood. A few plywood

plants also produced corn-ply, a structural

panel with veneer faces and a particle core.

Only two waferboard plants existed in the

United States in 1980, although there were

plans to add several more plants between 1981

and 1983 in the Great Lakes States or Maine.8

Unlike the plywood and lumber industries,

which require sawtimber-quality trees, composite structural panels use hardwoods; small,

lower quality trees; and, occasionally, mill

waste. The nonplywood panel products industry, therefore, probably will continue to be concentrated in the East, particularly in the Great

Lakes States, and the Northeast, where major

construction markets are located,

—.—7

See note 6.

‘Kidder, Peabody and Co., 1 nc., “Corn-ply, Waferboard, Or]-

ented Strand Board: Revolution in the Structural Panel Market?”,

I)e(; 24, 1980
Ch. II—SolId Wood and Pane/ Products ● 37

I

al

“ii

G

u

o

0

>

i i

—

m

u-l
38 . Wood Use: U.S. Competitiveness and Technology

Table 12.—Selected Statistics on the Lumber and Panel Products Industry, 1981

Value of product Value added - Number of

shipments (millions Number of employees

Establishment (millions of dollars) of dollars) establishments (thousand)

Sawmills and planing mills (SIC 2421) . . . . . $11,765.7 $5,552.2 7,544 151.0

Softwood veneer and plywood (SIC 2436) . 3,270 1,460 256 40.8

Hardwood veneer and plywood (SIC 2435) 1,200 430 321 21,3

Particleboard ., ... ... . . . . . . ... . . . . . 545 225 63 6.2

Table 13.—Number of Primary Timber-Processing Establishments in the United States,

by Industry and Type of Organization, 1972

Single-unit Multi unit

companies companics Total

Industry Number Percent Number Percent Number Percent –

Lumber manufacturing. . . . . . . . . . . . . . . . . . . . . . 21,554 95 1,132 5 22,686 100

Plywood and veneer manufacturing . . . . . 332 54 276 46 598 100

Woodpulp manufacturing . . . . . . . . . . . . . . . . . . . . 82 25 249 75 331 100

Other primary timber manufacturing . . . . . . . . 4,081 86 679 14 4,760 100

Total establishments . . . . . . . . . . . . . . . . . . . . . . . . . 26,039 92 2,336 8 28,375 100

a s ,n g l

e . unit cornpaflles operate at only one IOcatlon

bForest Sew Ice estimate based on Bureau of the Census data

SOURCE U S Department of Commerce, Bureau of the Census, Census of Manufactures, 1972 Volume/ Subject and Spec/a/ Sfatfst/cs (Washington, D C U S Govern.

ment Pnnttng Office, 1976)

Table 14.— Lumber Production by Mill Size, 1979

Mill size Production

(Million board feet) Number of mills percent (million board feet) Percent

Over 50 . . . . . . . . . . . . . . . . . . . 151 10 17,920 55

25-50, . . . . . . . . . . . . . . . 189 13 6,691 21

10 - 25 ......., . . . . . . . . . . . . . 288 20 4,588 14

5 - 10 ........, . . . . . . . . . . . . 272 18 1,908 6

3- 5 . . . . . . . . . . . . . . . . . . . . . 233 911 3

Other. ... . . . . . . . . . . . . . . . . 334 23 478 1

Total . . . . . . ... ... . . . . . 1,467 100 32,496 100

SOURCE 1981 Directory of Forest Products Industry

Table 15.— Large Mills and Production by Region and Size

Production range Number of mills

(million board ft) West South North and East

Over 50. . . . . . . . . . .“. . . . . . 115 32 4

25-50 . . . . . . . . . . . . . . . . . . 118 66 5

10-25 . . . . . . . . . . . . . . . . . . . . 114 136 38

5-10 . . . . . . . . . . . . . . . . . . . . . . 42 158 72

3- 5 . . . . . . . . . . . . . . . . . . . 27 112 94

Other . . . . . . . . 57 100 177

Total . . . . . . 473 604 390

Total production . . . . . . . . . . . . 22,131 8,287 2,078

Percent of total output . . . . . . . 68 26 6

SOURCE 1981 Directory of the Forest Products Industry
.

Ch. //—Solid Wood and Panel Products ● 3 9

Use of Solid Wood and Panel Products

Three sectors of the lumber and wood products industry group are among the 45 rapidgrowth industries whose compound annual

growth rates ranged from 6 to 20 percent between 1972 and 1978: 1) wood pallets and skids;

2) wood kitchen cabinets; and 3) structural

wood members, such as laminated or fabricated trusses, arches, and other structural

members of lumber (not including standard

softwood or hardwood dimension lumber). Although three-fourths of the rapid-growth industries attributed their success to new product

development, of the three rapid-growth, woodusing industries, only “structural wood members” listed new products as a key growth factor. 9 Two of these new products, laminated

beams and roof trusses, actually were introduced into the market during the 1950’s.

Two new developments, however, are trusses

that can be used to frame entire houses and

techniques for producing laminated beams,

joists, and girders of many sizes and shapes.

Such large, laminated beams and arches, frequently bent into specified shapes, have penetrated new markets, including the construction

of large indoor sports arenas, convention centers, and domes. Trusses, on the other hand,

have not opened many new markets for wood

products but have replaced larger dimension

lumber in light frame construction.

Other new products recently introduced include various types of fiberboard and particleboard. A medium-density fiberboard (MDF),

first produced in the mid-1970’s, has rapidly

expanded into furniture corestock markets

formerly held by particleboard and other panels. New types of particleboard include panels

fI [ I,s, [)~;~):l rl mf!n t of (;0 m m Crc e, op. [: it.

made from strands (thin shavings or slivers of

wood), flakes, or wafers, sometimes with veneer faces. These panels, first introduced in

Canada and the United States in the mid1970’s, now strongly compete with softwood

plywood for structural use.

The amount of lumber used in homes has remained fairly constant for several decades,

while the amount of plywood and structural

panels has increased. Panels for sheathing

(walls) have replaced sheathing lumber. Now,

however, plastic-foam sheathing is replacing

wood-based sheathing in some markets owing

to its superior insulation properties. New pane]

products are expected to replace plywood for

sheathing and underpayment (floors). The same

trend seems to have occurred in furniture manufacturing, where plywood and particleboard

have replaced lumber as furniture corestock

and have themselves been replaced by MDF.

Shipping pallets have been replacing wood

boxes and containers for materials handling.

New types of pallets, made with plywood decking, particleboard, or MDF, are expected to replace some of the existing hardwood lumber

pallets in the future.

In general, new products introduced by the

lumber and panel industries replace other

wood products already in use, rather than compete with other materials. If the forest industry hopes to expand the uses of wood, it probably will have to develop new products that can

compete with steel, aluminum, plastics, and

other structural materials, rather than products

that simply replace other wood products. This

probably will require greater interaction of

other professions involved in the construction

industry: building code offices and testing organizations, architects, and building contractors.
40 . Wood Use: U.S. Competitiveness and Technology

Industry Trends and Potentials

Most of the wood (over 96 percent in 1976)

entering mills for primary processing is used

as products or as an energy source. Wastes

from lumber and veneer or plywood mills are

used for fuel or for manufacturing particleboard, composite panels, pulp, or paper.10

While the wood products industry as a whole

is quite resource-efficient, opportunities for increasing efficiency still exist in three areas:

1) increasing the recovery of high-value primary products (lumber, plywood, particleboard); 2) expanding the use of underutilized

species, wood residues, and defective materials

now left in the woods after harvest; and 3) increasing the efficiency of the end use of wood

products.

Product Recovery

The efficiency of product recovery in lumber

mills, described as the “lumber recovery factor” (LRF), is measured by the number of board

feet (12 inches by 12 inches by 1 inch) of lumber

recovered from a cubic foot of log. Because the

nominal dimensions of finished lumber are

larger than the actual dimensions (a standard

finished 2- by 4-inch stud, for instance, measures approximately 11⁄2 by 31⁄2 inches), there are

actually 16, rather than 12, board feet of lumber

in a cubic foot of solid wood,

Lumber recovery efficiencies in the United

States currently average about 41 percent (LRF

of 6.5). With new technologies and processes,

the product recovery in lumber mills could

reach 60 to 88 percent (LRF of 10.0 to 13.0) for

medium-sized logs.11 The product recovery in

plywood mills averages around 50 percent.

New processes may improve efficiency slightly

by enabling the use of materials which at one

time were rejected as veneer stock. Finally,

wood for structural panel manufacture, Engineered panel products require roundwood to produce high-qua] ity flakes of

specified dimensions.

“Jerome Saeman, “Solving Resource and Environment Problems by the More Efficient Utilization of Timber, ” Report of the

President’s AdL’isorJ’ Panel on ‘rimber and the L’n L’irunrnent,

April 1973.

product recovery in particleboard, composite

panel, and fiberboard mills approaches 75 percent on a weight basis.12 Improvements are

aimed at reducing processing time, improving

panel quality, and increasing automation.

Since 53 percent of the wood entering sawmills is used to manufacture particleboard, fiberboard, paper, or energy, any increase in

lumber output for one use tends to reduce the

amount of wood available for other uses. These

tradeoffs can be important in balancing lumber

recovery efficiency with other production processes, including the need for energy.

Forest Resource Use

The forest products industry continually

seeks ways to use a larger proportion of the

woody biomass left in the forest after the marketable material is removed, Softwoods, which

are intensively utilized, could provide even

more wood material if the tops, limbs,

branches, and dead, dying, or defective timber

were used. The volume of dead and dying timber in 1977 was estimated to be 21 ft3—almost

double the amount harvested—and the volume

of residues left from logging came to 8 billion

ft3

in 1976. New products and technologies,

particularly in composite panel manufacture,

could use these materials, although the amount

that would be economically recoverable is unknown. As second-growth timber replaced old

growth and utilization standards changed, the

lumber and panel industries adjusted their

processes to use smaller logs. This trend probably will continue, Moreover, as the price of

high-quality softwood stumpage increases, advances in lumber processing and the development of composite panel products have increased the industry’s ability to use the vast and

largely untapped U.S. hardwood species.

IZ1~f;rsonal (communication w ith John Haygreen and Ja}’ Jo bn -

son with OTA staff member Julie K, Gorte.
Ch. I/—So/id Wood and Pane/ Products ● 4 1

Efficient End Use of Wood Products

The greatest opportunity to increase the efficiency of wood use may be in construction.

Current techniques could reduce substantially

the amount of wood used for home construction—particularly in single-family detached

dwellings–without reducing the quality of the

structure. Two developments are particularly

noteworthy: 1) truss framing and 2) engineered

panel assemblies, which combine sheathing

and framing. Increased use of single trusses to

frame floors, walls, ceilings, and roofs together

could yield greater wood savings. Some analysts estimate that truss framing could achieve

as much as 30 percent reduction in lumber use

over conventional construction practices.

Engineered assemblies or stressed-skin panels used for floors, walls, or ceilings, which

combine sheathing and framing in sandwich

panels or with adhesives, also may increase

efficiency of wood use. Such assemblies are

factory-built, as are trusses, and their use could

reduce the wood wastes on construction sites

from cutting and custom fitting, resulting in

less wood use while providing structural

strength and stiffness.

Improvements in wood use in manufacturing and shipping are more limited. Major improvements probably exist in the manufacture

of particleboard pallets or of pallets with

plywood or composite-panel decking. Although

construction techniques now being used may

produce a more durable and versatile pallet,

they probably will not replace traditional pallets to any significant extent. Conventional pallet manufacture requires lower capital investment than particleboard facilities.

Lumber Products

Lumber products are of three basic types: 1] Softwood

dimension lumber, 2) boards and finish lumber, the lumber

dimension lumber, the mainstay of

industrv, is manufactured in five

and 3) timbers. Boards* and finish lumber are

less than 2 inches thick and 1 inch or more in

width. Dimension lumber is between 2 and 5

inches thick and at least 2 inches wide. Lumber

that is 5 inches or more is classified as a timber.

* For purposes of this report, the term “hoard” is used only

in reference to panel productt, one-in(:h lumber will be referred

to ;is “f]nish lumber. ”

types of sawmills: 1)small-log mill; 2) stud mill;

3) large, common-log mill; 4) large, grade-log

mill; and 5) high-deduct, 1arge-log mill. Distinguishing factors among these sawmill types are

log diameter and type of lumber product (table

16). The most common mill is the small-log

mill, which produces dimension lumber for

light frame construction.

Table 16.—Types of Softwood Sawmills and Their Primary Products

Sawmill type “- ‘

-- ‘-

Typical log diameter Primary products produced

Small-log dimension mill ., .. .5” to 16” Random length dimension -

lumber

Stud mills, ... ... ... , ... ,4” to 9” Studs 2” x 4” X 8‘ nominal

Large, common-log mill ... , 16” to 30” Random length dimension

lumber

Large, grade-log mill ., ... . . 15” and larger Common, shop, and clear

lumber

High-deduct, large-log mill . . Large logs with greater than Clears and high-grade

30 percent deducta

commons

Adapted from Wllllston 1-9;; – “

aDeduct[on In recoverable lumber volume due to defects (n the logs

SOURCE Envlrosphere Co Wood /ts Present and Poten(/a/ Uses contractor report to OTA 1982
42 . WOOd Use: U.S. Competitiveness and Technology

Lumber Manufacture

The basic processing steps for lumber manufacturing are shown in figure 8. Materials and

energy flows of a typical sawmill are shown

in figure 9. The efficiency of lumber recovery

tends to vary with mill size, with larger mills

achieving higher recoveries.

Potential Improvements in Milling Efficiencies

and Lumber Manufacture

In 1979, lumber constituted almost 70 percent of the weight of all lumber and panel products produced in the United States and 53 percent of all wood products, except pulp and

paper, consumed in that year.13 Thus, even

small improvements in milling efficiency can

result in significant savings of the Nation’s

timber resources, particularly softwood. Several such improvements can be made in lumber

manufacture by: 1) improving lumber recovery

or wood-use efficiency in sawmilling, 2) decreasing energy requirements, and 3) improving grading procedures.

Improving Lumber Recovery and Wood Use

The following existing technologies probably

have the potential to more than double the efficiency of converting roundwood into lumber

products (table 17). By installing or adopting

technologies such as BOF, PLV, and SDR, the

efficiencies of sawmills probably could be increased substantially, The potential increase in

lumber recovery efficiency for PLV, EGAR,

and BOF is shown in figure 10. In addition, several new technologies, such as SDR, corn-ply,

and composite lumber, probably can reduce

Figure 8.— Flow Diagram of a Typical State-of-the-Art Small-Log Sawmill, Indicating Process Waste Streams

r F

Log * 1 > e Stabber *

Twin

-

Trl- 1

band mill

Bucking Chips Sawdust Chips Sawdust Sawdust

Wood J

Chips

Product

sorter

NOTE” A log profile is shown at each machine (top) The shaded areas Indicate material which is chipped away, while verticle I!nes in other cross-sections indicate saw Ilnes

SOURCE” E M Williston, Lumber Manufacfurlng The Design and Operation of Sawmi//s arrd Paper Mi//s (San Francisco. M!ller Freeman Publications, 1976).
Ch. II-Solid Wood and Panel Products . 43 ——. —.

Figure 9.— Present and Predicted Materials Balance for Softwood Lumber Based on Ovendry Weight

(OD wt.) (sawlog weight includes bark)

Sawdust

the lumber industry’s dependence on high-value softwood timber, whose scarcity (deflated

price] has increased at the rate of about 2 percent per year (compounded) over the last century. The SDR process and the manufacture of

composite lumber and timbers allow manufacturers to utilize hardwoods, defective timber,

and wood residues formerly considered unmerchantable,

Expanding the resource base by using larger

proportions of the wood produced in the forest is one of two major opportunities that exist to improve total utilization efficiency of

wood in the United States. The other is increasing the efficiency in the way lumber is used

(conservation). However, increasing the efficiency of mills may not significantly reduce the

demand on the forest resource, unless increasing amounts of forest residues can be harvested

economically and transported to mills. For example, the efficiency of lumber recovery may

reduce the amount of residue available to produce energy, and pulp, paper, particleboard,

and other fiber-based panels. Nationwide, the

unused wood from primary processing consists

of 52 percent softwoods and 48 percent hardwoods and represents 7.1 million tons of material, A significant portion of this material

probably comes from lumber manufacturing,

although the exact quantity is unknown.

Improving Yields in Traditional Sawmills

There is a practical limit to the amount of

lumber that can be recovered from any log,

However, some new processes can increase the

lumber-recovery efficiency of dimension lumber without major sawmill modifications; e.g.:

1) the BOF program, which can produce higher

grades and increase recovery of lumber; 2) the

SDR process, which enables the use of hard-
Table 17.—Summary of Major Technologies for Improved Lumber Manufacture

—

Technology Stage of development

BOF - Commercially available

EGAR Process IS developed; no

significant commercial use.

SDR Process is developed; no

significant commercial use.

MSR Commercially available.

PLV Lumber

-

Commercial availability limited —

to a few specialty products.

Effect on resource base Effect on recovery

None Theoretical increase of 20°/0

over conventional

sawmilling.

Possible increased small log Increases recovery 10-130/0

utiIization,

Increased hardwood utilization. Reduces defects in hardwood

lumber; increases lumber

value.

None Reduces variability within

lumber grades, allowing

more efficient use of lumber

in construction.

Theoretical yield of 70-90°/0

Corn-Ply Lumber Not commercially available

Improved Drying (solar No significant commercial

kilns, high temperature development.

drying, vapor

recompression,

dehumidification)

SOURCE: Office of Technology Assessment

Allows use of hardwoods, Theoretical %O/. recovery,

wood residue, defective

wood.

— Lower energy requirements;

reduction in defects.

Barriers to implementation

Field results have shown

average 40/0 Increase over

conventional sawmilling.

More costly to manufacture;

more labor-intensive.

Higher drying costs; requires

high-temperature kilns.

Modification of codes to allow

most efficient use of MSR

lumber.

Development of continuous

laminating presses; lack of

accepted method for

assigning product strength

values; requires new milling

facilities.

Requires new milling facilities

or combination of veneer

and particleboard facilities,

Usually higher capital

investment and/or longer

drying time.

Estimated time

scale to

significant

contribution —.

o

15-20

10-20

0-5

15-20

15-20

15-25
Ch. II—So/id Wood and Panel Products . 45

Figure 10.—The Maximum Yield of Lumber From

Conventional and Innovative Processes

I

5 6 7 8 ‘j 10 11 12 13 14 15 16 17 lb 19 20

Log diameter

woods, previously limited by their tendency to

warp; and 3) the EGAR process, which reduces

waste and can produce higher quality lumber,

Best Opening Face.—The initial sawline, or the

opening face cut, sets the position of all other

sawlines and therefore has a significant effect

on lumber recovery efficiencies and grades.

Deciding how to make the initial cut often is

left to the judgment of the head saw operator.

While a skillful operator can achieve high efficiencies, a computer can simulate various

sawing patterns and more quickly choose the

optimal opening face. The BOF, a computer

program for selecting the best first cut, was developed by FPL nearly 10 years ago. In 1973,

the Forest Service initiated a sawmill improvement program to demonstrate the BOF concept. Under laboratory conditions, BOF yields

6 to 90 percent more lumber from 5- to 20-inch

logs and averages 21 percent more lumber recovery than does conventional sawing.

Saw-Dry -Rip .—The SDR process can increase

the amount of sound, defect-free lumber recovered from hardwood timber by modifying

slightly the conventional milling practices of

sawing, ripping into lumber, and then drying,

With SDR, crooks, bows, and twists in hardwood lumber may be reduced by first sawing,

then high-temperature drying, and finally ripping” into lumber. Drying larger pieces at high

temperatures by SDR minimizes the effect of

the stresses that develop within wood as it

grows, SDR may result in a lower LRF of green

(undried) lumber than conventional milling,

but this is generally more than compensated

for by the reduction in warp.

Edge-Glue and Rip.—With EGAR, logs are sawn

into flitches* * and lightly edged prior to drying.

* Kipplng is sawing lengthwlsr or [)a ra 1 lel to gra 1 n, a 10 I)g the

l[)ngitudina] axis of the lumber,

* * A flitch is a crosswise slice from a log, with two sawn faces

and two ro’u nded, or u nsaw n edges.
46 . Wood Use: U.S. Competitiveness and Technology

They are then glued edgewise into panels, and

the panels are ripped into lumber. This reduces

the amount of wood lost in edging, which usually sacrifices some sound wood from lumber

edges in order to produce solid lumber of

standard widths. Ripping can be done to yield

the highest grade and strongest lumber by

avoiding knots near the edges of the lumber.

The EGAR process theoretically can increase

lumber recovery from 35 to 77 percent from

logs of 5 to 20 inches in diameter.14 It is estimated that EGAR can increase the output of

finished dimension lumber by 10 to 13 percent

by eliminating edging loss.15 Moreover, EGAR

lumber has greater strength and less warp than

standard lumber. However, the process itself

is more labor-intensive than conventional lumber manufacture and requires additional drying, which may increase manufacturing costs.

Several new lumber-drying processes that

could reduce energy consumption may come

into wide use in the future, Because the lumber

industry is a small energy consumer, savings

in energy use by the lumber manufacturing industry probably will not contribute significantly to national energy conservation; they could,

however, become more important to lumber

manufacturers as energy prices increase. (The

lumber industry, however, is a minor energy

purchaser and is capable of producing much

of its own energy through the use of mill

wastes. )

Producing Composite Lumber and Timber Products

BOF, SDR, and EGAR are marginal modifications to conventional sawmilling. Lumber,

or lumberlike products, also can be made from

wood particles or veneer, as well as from solid

wood or edge-glued pieces, Manufacturing

such composite lumber can dramatically increase lumber recovery efficiency and extend

the timber resource base through use of wood

waste material and hardwoods, It is unlikely,

however, that composite lumber products will

replace conventional 2 by 4 framing lumber.

‘V-hernan, op. cit.

Is(j[:orge B. Harpo]e, Ed Williston, and Hiram H. Hallock,

“E(lAK Process hlakes Wide-Dimension Lumher From Small

],ogs, ” ,$c)uthern I,umberman, Dec. 15, 1977.

Most opportunities for using composite lumber

are in larger applications—for girders and

beams-or for specialty applications. Two major processes have been developed to manufacture composite lumber and timber products:

PLV and corn-ply.

Parallel Laminated Veneer.—Also known as

press-lam and laminated veneer lumber (LVL),

the PLV process consists of laminating (gluing)

veneers with all plies parallel (as contrasted to

plywood, where the veneers are laminated with

grains perpendicular) to make dimension lumber or timbers. Like plywood veneers, the

veneer sheets are press-dried, coated with

adhesives, laminated in overlapping fashion,

pressed, and ripped to desired dimensions.

PLV has a number of advantages:

● it produces high-quality products from

low-quality raw material or hardwoods;

. lumber or timber dimensions are not limited by log size; and

● it can convert logs into ready-to-use products in 1 hour.

In general, PLV produces higher grade lumber than does conventional lumber manufacturing. Moreover, PLV specialty products and

large structural timbers from PLV might be attractive commercially; at least one firm now

markets a joist, called Micro-Lam, * made from

PLV. PLV also can be used to manufacture

nonstructural wood products like millwork and

cabinetry. Lumber recovery efficiency from

PLV can be increased from an efficiency of 53

to 91 percent for 9- to 20-inch logs, an efficiency significantly greater than that theoretically attainable from any other lumbermaking

process.

Despite its advantages, PLV may not make

significant penetration into conventional dimension lumber markets in the near future.

PLV manufacture requires equipment that cannot readily be adapted to conventional sawmills; thus, shifting to PLV probably will require entirely new mills with high capital costs.

As existing sawmills are depreciated, PLV facilities may be built as replacements, particu-

*Trademark of the Trus-Joist (lot-p,
Ch. II-Solid Wood and Panel Products . 47

larly if real stumpage values increase and if

building codes are modified to recognize fully

the superior properties of PLV lumber. However, it may be possible to modify plywood or

panel mills to produce composite lumber and

products such as composite timbers (beams,

joists, arches, girders, and the like), The substitution of composites for dimension lumber

may occur slowly unless the price of high-quality softwood logs significantly increases. PLV

can be used for large structural elements, such

as beams or timbers, that vary in cross section

across their length to meet strength requirements.

Com-ply.—Com-ply consists of a structural

composite core, like particleboard, with veneer

faces. It can be made into studs, larger dimension lumber, or panels. Corn-ply studs are

strong enough to substitute for standard studs

on a one-for-one basis in exterior house framing. The particleboard core constitutes 70 to

80 percent of the product and can be made

from hardwoods. Because a corn-ply mill can

use nearly all of its residues to produce the core

material, it can operate with only 5 percent

waste, a lumber-recovery efficiency of 95 percent. Economic analysis of corn-ply lumber

production shows, however, that it is unlikely

that corn-ply lumber will be very competitive

with either conventional or PLV lumber,

Decreasing Energy Requirements

Up to 90 percent of the heat energy required

in lumber processing is consumed in drying

lumber to a moisture content of 13 to 16 percent. Lumber normally is dried in a steam kiln

(although air drying is used sometimes) in

which heated air is circulated. Kilns may be

heated by natural gas or propane directly or,

more commonly, by steam coils. Softwood lumber requires from 2 million to 4 million Btu/

thousand board feet while hardwoods require

up to 6.5 million Btu. Several new drying technologies have been developed, including: 1)

high-temperature kiln drying, 2) continuousfeed drying, 3) dehumidification, 4) predrying,

5) pressure drying, 6) solar drying, 7) solar dehumidification, 8) vacuum, 9) vacuum-radio

frequency, and 10) vapor recompression drying, Of these, continuous-feed, dehumidification, pressure, solar dehumidification, vacuum,

and vapor recompression drying may gain

some commercial acceptance by 2000, although

none seems likely to replace conventional

steam kilns.

Improving Grading and Quality

Dimension lumber is graded according to

strength and stiffness, Grades determine what

end uses may be made of construction lumber,

Improved grading systems are being developed

to better determine the end-use properties and

characteristics of lumber and thereby avoid

overbuilding with lumber products or using

high-quality material where lower grades are

suitable. Because different defects such as

twist, bow, crook, rot, or knots affect mechanical properties differently, current practices of

visual grading often result in a wide variability

in lumber properties within each grade. Builders often use lumber of better quality than is

needed for construction to account for this variability in meeting building codes and avoiding

liability.

Improved ability to determine the strength

and stiffness of lumber, together with building

code acceptance of better design practices

based on more precise grading, could result in

significant resource savings. Since lumber

strength is related to the presence of knots, a

system that can determine precisely the effect

of each knot on each board would be quite valuable. As yet, it is unavailable, Another development that could aid in making more efficient

use of framing lumber is a more precise understanding of the strength required in end-use

applications, so that lumber strength can be

matched to design specifications. Two major

efforts are under way to improve grading in

the United States: 1) MSR, an alternative grading technology; and 2) ingrade testing, a research program,

Machine Stress Rating is a mechanical grading system that measures lumber stiffness in

a nondestructive, stress-rating machine. It does

not eliminate the use of visual grading but instead gauges the stiffness before visual graders

determine the grade based on defects.
48 ● Wood Use: U.S. Competitiveness and Technology

MSR lumber, with a narrower range of variability than visually graded lumber, reduces the

amount of high-quality lumber needed to meet

particular design specifications. The primary

market for MS R-graded lumber is in truss fabrication, where lumber is used for roof, floor,

and wall framing. The amount of lumber that

could be saved using MSR varies and depends

on the design of the truss.

The In-Grade Testing Program was initiated

in l977 by FPL to develop more precise data

on mechanical properties of various grades and

species of lumber and to assess the importance

of these properties on the design and engineering of structures. Tests of walls, floors, and full

scale indicate that houses generally are overdesigned. Information from the In-Grade Testing Program may be used in conjunction with

engineering structural analysis to improve the

efficiency of lumber use in light frame construction.

Consumption and Use of Lumber Products

in the United States

Lumber consumption in the United States

has been relatively stable for several decades,

increasing from just over 5 billion ft3 in 19.50

to almost 6 billion ft3 in 1979.16 At the same

time, per capita consumption of lumber has declined by over 20 percent over the past three

decades (fig. 11).

Construction (including new residential construction, upkeep, improvement, and nonresidential construction) uses about 60 percent of

all lumber consumed in the United States. The

remaining 40 percent is used in shipping, manufacturing, and other uses, with shipping

accounting for 43 percent of lumber used for

nonconstruction purposes. New residential

construction alone accounts for 40 percent of

all lumber consumption.

New Residential Construction

Historically, the housing industry has experienced wide swings in residential construction activity, and there are indications that that

I%ee note 2.

Figure 11 .—Per Capita Consumption of Lumber

1950-79

activity may continue to be erratic and uncertain. An upturn in homebuilding could drive

softwood log prices up, increasing the incentives for lumber manufacturers to streamline

operations and to increase product yields to remain competitive. Low rates of residential construction could force many small lumber mills

out of business, concentrating the industry in

the larger mills, which tend to be more efficient. Other developments in the homebuilding

industry also affect the lumber industry, such

as trends toward smaller houses and multifamily dwellings,

The amount of lumber used per unit depends

largely on the type of dwelling constructed and,

to a lesser extent, on building techniques and

design. Single-family detached dwellings use

approximately twice the amount of lumber

used in multifamily dwellings and 4.5 times the

amount used in mobile homes. Most singlefamily dwellings and small clustered units (e.g.,

duplexes) are built onsite. Preassembled lumber products, such as trusses, have successfully

penetrated the market for roofs in light frame

construction and now account for the majority

of roof framing. Floor trusses have been less

successful, although they are gaining in acceptance in some areas. Trusses used to frame

whole houses (fig. 12) recently have been de-
Figure 12.— The Truss Frame System

Th IS truss framed system combl nes floor, wal Is, and roof

Into a u r] !t Ized f ramp for st r uct L ra I cent I n u It y from the fou n

d a t I o n u p t o the r I (j q e

S(JU RCE USDA Forest SFrV Ice Forosl Products Laboratory

veloped by the FPL and are in limited use

today.

Residential Upkeep and Improvement

Home upkeep and improvement accounted

for 14 percent of the lumber consumed in the

United States in 197617 and almost 8 billion

board feet of softwood lumber in 198018 compared with 4.7 billion in 197o. Indications are

that such use may increase. The use of lumber

per thousand dollars of expenditures on upkeep and improvement may have declined

slightly, however, primarily because of substitution of panel products for lumber.

New Nonresidential Construction

New nonresidential construction accounted

for just under 10 percent of the lumber consumed in the United States in 1976 for a range

IB( ;h 1 rl(; (It t I I, u m her a n{i PI }IW ood

F’ore\t I)rodu[,ts I ndustrj’ and the

A[:apulco, Llcxlco; Apr. 3-4, 1982.

Panel products are used

Forecasting, Inc., “The

80’s. Think Tank #l ,“

Plywood and

for many things,

mainly in construction, Single-family housing

construction uses 43 percent of the plywood

and 25 percent of the particleboard and other

Ch. II—Solid Wood and Panel Products ● 49

of public, private, and commercial projects.

Building construction, including commercial

and other buildings, accounted for about twothirds of the lumber used in new nonresidential construction in the early 1970’s.* Total

lumber use for new nonresidential construction, which normally responds to general economic activity, is expected to double in the next

50 years, primarily because of economic

growth. 19

Manufacturing

Manufacturing, primarily of furniture, accounted for 11 percent of the lumber consumed

in 1976. Much of the lumber once used for

corestock has been displaced—first by particleboard, then, more recently, by medium-density

fiberboard.

Shipping

Shipping accounted for 17 percent of the

lumber consumed in 1976. Two-thirds of the

lumber in shipping was used for pallets, with

the remainder used for dunnage, blocking,

bracing, and wooden boxes. These latter uses

have been declining for two decades and are

expected to continue declining.

Most pallets are made of low-grade hardwood lumber, usually rough (unsurfaced) lumber. Pallet markets, which consume the majority of the hardwood lumber produced in the

United States, expanded rapidly during the

1970’s for materials handling, and some further expansion is expected. The rate of increase

in industrial pallet use, however, is expected

to decline as the market becomes saturated.

* Utilities, water and sewer systems, high ~tays, and other nont)uilrling construction accounted for the remaining one-third.

‘@.See note 5.

Panel Products

structural panels produced in the United States

(table 18), Panel products also are popular in

residential upkeep and repair, accounting for

23 percent of the plywood and approximately
50 ● Wood Use: U.S. Competitiveness and Technology

Table 18.—Plywood and Panel Products Consumed in

New Residential Construction in the United States,

1962-80

Type of home (ft2, 3/8” basis)

Year Single family Multifamily Mobile

1962 . . . . 3,010 1,800 “ 1,840

1970 . . . . . . . . 5,385 1,910 1,300

1976 ., . . . . . . . 5,815 3,255 1,610

1978. , ... . . . 5,600a2,650 550

1980 . . . . . . . . 5,640 3,105 555

.-

aF[gUT~~ for I ip 76 Include only Plywood

SOURCES USDA Forest Service, An Ar?a/ys/s of the T(rnber S(tuatlon In the

Un/fed States, 1952-2030, Review draft, 1980 (Includes ftgures from

1962, 1970, and 1976)

Thomas P Clephane, Out/ook for T/mber Supp/y/Dernarrd Through

1990, Morgan Stanely Investment Research, 1982 (Includes figures

from 1978 and 1980)

40 percent of the structural panel market in

1976. The remainder is used in manufacturing,

shipping, and other uses.

There are three types of plywood and panel

products:

●

●

●

●

Plywood—a flat panel made of laminated,

crossbanded wood veneers, where each

layer is arranged with the grain at right

angles to its adjoining layers.

Structural composite panel—a panel made

of wood particles—e. g., chips, flakes, wafers, and strands—pressed into a flat panel

and simultaneously bonded with a thermosetting adhesive.

Particleboard—a nonstructural panel

made from small wood particles bonded

into a flat panel with adhesives under heat

pressure.

Fiberboard—a flat panel made of individual woodpulp fiber (like paper) bonded together. Insulation board and hardboards

are special kinds of fiberboards.

Plywood

Current Plywood-Manufacturing Processes

Plywood manufacture consists of two processes: veneer production, and layup and gluing of the veneers into plywood (figs, 13 and

14). The five methods for manufacturing veneers for plywood include: 1) rotary cut, 2) staylog cutting, 3) cone cutting, 4) sliced veneers,

and 5) sawn veneers. Over 90 percent of the

veneer produced is rotary cut, i.e., peeled on

a lathe. Other methods produce specialty hardwood veneers used in furniture and cabinetry.

To produce plywood, the veneer logs first are

steamed and then are sent to a lathe that peels

off a thin, continuous ribbon of veneer. The remaining core of about 4 to 5 inches subsequently is used for dimension lumber or is chipped

to produce pulp and paper, particleboard, or

fuel. The veneer sheet itself is cut into sheets

by a clipper, which also removes knots and defects. After drying, the veneer is placed on an

assembly line, where adhesives (usually phenol formaldehyde) are applied, and the veneers

are stacked to form plywood. A typical five-ply

plywood layup line can produce 6 to 8 five-ply

panels or 12 to 16 three-ply panels per minute.

Following layup, a panel is cold-pressed to consolidate it before loading the press, It is then

hot-pressed under pressures of about 15o

pounds per square inch (psi) at temperatures

ranging from 2400 to 3000 F. After the panels

cool, they are trimmed and squared, sometimes

sanded, and then graded and prepared for

shipment,

Potential Improvements in Plywood Manufacture

Current plywood recovery rates run between

47 and 53 percent and probably average 50 percent.20 Less than 1 percent of all roundwood

used in plywood manufacture ends up as

waste. Residues from plywood mills are used

to produce lumber, particleboard, pulp and paper, fiberboard, or energy.

Because plywood mills now are capable of

using smaller logs than in the past, increased

efforts are being made to use hardwood for

structural plywood, Technical developments

in plywood manufacture are aimed primarily

at: 1] expanding the number of species and

quality of the timber that can be used for

plywood; 2) increasing automation; 3) reducing energy requirements; and 4) increasing the

degree of computer-assisted process control,

particularly in peeling and clipping.

20 See note 8.
Ch. II—Solid Wood and Panel Products ● 51

Figure 13.— Flow Diagram of a Small-Log Plywood Mill

Bucking Lathe Peeling ~ Clipping

Sawdust

Debarking

Chips I

Lumber Chips Chips — Drying

Log yard

Expanding the Range of Usable Material.–The plywood industry historically has depended on a

plentiful supply of large-diameter, straight, rotfree softwood timber. However, over the years,

large softwood logs have become very costly,

and future supplies are uncertain. As a result,

in the early 1960’s, the plywood industry began

to move to the South, attracted by inventories

of largely unutilized Southern pine. By 1980,

the South was producing nearly as much plywood as the West, generally using smaller logs.

Technology still is being sought to handle and

process small logs and expand the range of logs

that can be peeled.

Currently, 25 percent of the veneer logs are

considered unpeelable. 21 Some mills lose 40

percent of their logs from splintering, crack-

‘4] }J1.,l [~h J I;rfJr]\/,CiA,

“ I)r(’i f’nt in~ [’(III(;(JI Holt S1] inollt, ’” .llo(i-

(‘[ /1 1’/\ LI ( )(){1 /“(’( h/) /(/ L]( ‘5 , ~) 1’( )( ,(’( ‘( I I 1) g> ( ) t t hll ,s(JI”[~l) t 11 1’1 \“ \i”[ )()(i

(:1 1[}1( . I’ortlrll)(l. ( )1’(’ . hldrl t) 1 (17’)

ing, and breakage on the lathe caused by toosmall logs or internal defects. Because of the

high value of veneer logs, increasing the

amount of peelable material can greatly improve the productivity and profitability of the

mill. Some techniques used to prevent wood

losses include: 1) better chuck design to hold

and rotate the logs against the knife; 2) new

pressure-bar designs to position the knife on

the log; 3) heating the log, which some believe

can reduce the torque needed to peel the log;

and 4) using backup torque rollers to increase

deliverable torque at the lathe.

New types of pressure bars mounted on the

lathe to control veneer thickness and peeling

performance show some promise, Roller bars

produce lower forces needed for peeling than

do conventional, fixed bars, but initially cost

more and have higher maintenance costs. The

recently developed steam-heated, contoured
52 ● Wood Use: U.S. Competitiveness and Technology

Figure 14.—Material Balance for Softwood Plywood Based on Ovendry Weight (OD wt.) (veneer log weight includes bark)

Phenol-formaldehyde resin

0.01 \

1.0 ton

o

0

0

0

Panel trim and reject

0.07

Shavings and end trim

0.01

Chips

0.04

Sheathing plywood

0.45

Particleboard furnish

0.08

Studs

0.06

0.30

Total 1,01

SOURCE C W Boyd, et al Wood and F/t,er Ml ) 1 72 1976

fixed bar, however, may be as effective as the

roller bars without the high cost.

Increasing the chuck* diameter could increase the amount of peelable roundwood, but

larger chucks increase minimum core size as

well. Further chuck modification is unlikely to

produce significant increases in veneer recovery, and the backup roller was developed as a

means of providing this auxiliary torque. Research on the optimum design and location of

the backup roller is under way.

Finally, some efforts are being made to explore the potential of hardwoods in structural

plywood production. Results of several studies

indicate that construction-grade hardwood plywood made from a mixture of high- and lowdensity species could be competitive economically with softwood construction plywood.22
Ch. II-Sol/d Wood and Panel Products ● 53

.
54 ● Wood Use: U.S. Competitiveness and Technology

Particleboard

Current Particleboard Manufacturing Processes

Other than plywood, most structural panels

currently manufactured in the United States

are particleboard made from a variety of wood

particle types. The basic steps involved in

standard particleboard manufacture (called

dry-forming), are shown in figures 15 and 16,

During the process, wood first is reduced to

the desired particle geometry by flaking, disking, hogging, or hammermilling. The particles

are dried using rotary-drum dryers or horizontal fixed dryers and classified according to size,

They are blended then with adhesives and

waxes and formed into a mat, sometimes with

coarse particles at the core and finer particles

at the surface. 27 The mat then usually is hotpressed to the desired thickness and density,

allowing the adhesive to cure. Panels then are

cooled, trimmed, sanded, and graded.

A small proportion of the particleboard produced is wet formed, or extruded, wherein adhesive-coated particles are forced through a hot

die. The extrusion process produces a particle-

‘-~[!rlt; ~1’[;[l~~rt ;]lIc1 ~“r[;ci IdInh, “Arl ()~wrview’ of (:omposite

1100 [’(1s, “ F’urniturc l~c.sign ,~nd .lfanufa[:turing 54(3), Marc h

1982,

Figure 15.— Materials Balance for

Particleboard Based on

board that is weak in bending and stiffness and

low in dimensional stability and generally is

used for specialty purposes. To overcome

strength problems, extruded particleboard

often are honeycomb-shaped or fluted,

Potential Improvements in Particleboard Manufacture

Many particleboard markets have been declining due to competition from new structural

panel products in construction and from medium-density fiberboard in furniture corestock.

Some particleboard probably will continue to

be employed in nonloadbearing structural use

and in a variety of home and miscellaneous

uses, but only if it is cost-competitive with other

products. Particleboard manufacturers have

been facing increased competition for raw materials—largely planer shavings and other sawmill residues—from pulpmills, As a result, the

particleboard industry may focus on improving the utilization of forest residues and on developing economical harvesting and transportation methods.28

the Manufacture of Underpayment

Ovendry Weight(OD wt.)

Urea-formaldehyde resin Wax

0.08 0.007

1.0 ton

planer shavings, sawdust

plywood and lumber trim

(OD wt.)

Particleboard

(5/8 in. thick)

0.979

Sander dust 0.094

Kerf from panel saws 0.014

v

x }

J

Total

Fuel

0.108

1.087

NOTE Total IS more than 10 because of resin and waxes percentages may vary

SOURCE C W Boyd, et al , “Wood for Structural and Architectural Purposes, ” Wood and F/ber 6(1)’ 1-72, 1976
Ch II. -Solid Wood and Panel Products ● 5 5

Figure 16.—Materials Balance for the Manufacture of Structural Particleboard Based

(OD wt.) of Chipping and Flaking of Sound Wood

on Ovendry Weight

NOTE Va\ues !n parentheses are those associated with chlpplng and flak!ng cull logs or other forms of residue with some rot Total IS more than 10 because of the

addltlon of resin and waxes Percentages may vary

SOURCE C W Boyd, et al “Wood for Structural and Architectural Purposes, ” Wood and Ftber 6(1) 1.72 1976

Structural Composite Panels

Structural Composite-Panel Manufacturing Processes

Structural composite panels were developed

in an effort to get more out of the wood resource, a focus still primary in the industry.

Nearly all the new panel products developed

in the last two or three decades can use hardwoods and some defective wood material as

well, although high-quality structural panels

usually require roundwood for raw material.

In the 1980’s, R&D efforts likely will be aimed

at improving the efficiency and engineering of

particleboard-panel products made from flakes,

chips, particles, and strands to meet design requirements.

There are three general types of new panel

products, the first two of which are expected

to provide competition to plywood in structural

use: 1) waferboard; 2) OSB; and 3) veneer-faced,

composite-core panels.

Waferboard, or flakeboard, originally introduced in Canada, is a panel made of wood wafers or large, flat flakes. High-quality flakeboard

can be made using as much as 8 percent bark

(although too much bark can cause problems)

and 12 percent decayed wood. It also can be

made from all hardwood and thus offers opportunities to extend the resource base and produce sheathing-quality panels at lower cost

than possible with softwood plywood. The

alignment of particles has proved difficult in

waferboard, however, and the nonaligned particles produce a product with much lower

strength and stiffness than plywood. However,

waferboard is strong enough to substitute for

plywood in many sheathing applications. Waferboard has been accepted widely in Canada,

and there are several waferboard plants operating in the United States. A basic manufacturing flow diagram is shown in figure 17.

Oriented strand board is made from strands

or ribbon-like pieces that can be laid down in

layers to produce a three- or five-layer board

with crossbanded construction much like plywood (fig. 18). The structure of OSB may overcome the strength problems of waferboard,
56 ● Wood Use: U.S. Competitiveness and Technology

Figure 17.— Idealized Typical Waferboard Process

Raw

material

Press

Institute of Technology, June 1982

OSB, unlike waferboard, uses liquid resins,

which could reduce adhesive costs. These resins also may provide flexibility in the type of

resins used, which may be useful if the industry moves to isocyanate (similar to Crazy Glue)

binders in the future. 29

Veneer-faced composite-core panels (comply) use particleboard cores with veneer faces,

like plywood. These products have engineering properties similar to those of plywood, but

sometimes are stronger and stiffer. However,

their dimensional stability is somewhat less

than that of plywood, and they are more dense,

Corn-ply may be manufactured to a limited ex-

.

29 —

Se~ note 8.

tent in existing plywood or veneer facilities;

however, it probably will not compete with

waferboard and OSB.

Potential Improvements in Structural

Composite Panel Manufacture

In addition to extending the resource base,

primary emphasis in R&D on structural panel

products is in improving product performance,

improving processing, and conserving energy.

Improving Product Performance.—Plywood retains much of the natural strength and physical characteristics of the original wood. Particleboard cannot match the performance of

plywood in many high-stress, structural appli-
Ch. Ii—Solid Wood and Panel Products • 57

Figure 18.—ldealized Typical Oriented Strand Board Process

Raw

material

Flake

1

resin

Form and

align 4

surface

J{

SOURCE Henry M Montrey Ill Current Status and Future of Structura/ Pane/s In the Wood Products /ndustry, M S the.ws, Massachusetts

Institute of Technology, June 1982

cations and therefore has been used mainly for

floor underpayment and furniture corestock rather than sheathing, Research in producing

structural panels that can substitute for plywood in sheathing and other structural applications has been a major R&D focus. Efforts have

centered on controlling particle geometry and

alignment during mat formation.

Improving Processes .—Developments in processes for aligning particles and pressing panels

show future promise. Particle alignment [orienting wood particles with parallel grain) within a composite structural panel helps retain

more of the desirable mechanical properties of

solid wood, but allows the use of a variety of

wood raw materials. This is a major factor in

producing composite panel products suitable

for high-stress, structural applications.

Both mechanical and electrostatic processes

are used to align the particles, Mechanical

alignment is used to produce OSB. Electrostatic alignment polarizes wood fibers or particles

that become aligned with the electrical lines

of force. These technologies are not developed

fully; however, work on fiber alignment is continuing. Wafers historically have proven difficult to align. Equipment that could produce

aligned waferboard may provide additional

stimulus to this growing industry,

Developments in pressing panels have not

been dramatic, but there is an ongoing inter-
58 ● Wood Use: U.S. Competitiveness and Technology

est in continuous presses to speed processing

and reduce bottlenecks associated with

conventional presses. Although continuous

presses are available for producing thin boards

and medium-density boards, those that can be

used to produce a wider variety of structural

panel products have yet to be developed,

Another trend in board-pressing is toward the

use of closed-liquid heating systems rather than

the conventional, steam-heating systems. Liquid heating systems provide higher temperatures, have less temperature variability, are less

likely to have “cold spots, ” and save at least

20 percent of the energy required to operate

a comparable steam-heated system.

Conserving Energy .—Particle drying is a major

energy consumer in the manufacture of panel

products. Innovations in drying have been

modest.

Fiberboard

Current Fiberboard Manufacturing Processes

Fiberboard, insulation board, and hardboard

are manufactured from individual fibers or fiber bundles, rather than from wood particles.

The wet process, which can be used to manufacture any of these products, was first developed in 1924 by W. H. Mason and is known

as the Masonite process. The prepared wood

is heated by steam in a pressure vessel called

a “gun.” The pressure in the gun is raised from

600 to 1,000 psi and then suddenly is reduced,

causing the chips to explode into a coarse mass

of fiber which is reduced further by milling.

The fibers are formed into a mat, much like paper, and finally pressed in a hot press.

Hardboard also can be manufactured using

a dry process in which the chips are presteamed and ground in a mill. Most fiberboard

currently is produced using mechanical disk

refiners and thermomechanical pulping. Usually, resin and wax are applied to the fibers

prior to milling, and the fibers are formed into

a mat and hot-pressed like particleboard. The

dry process uses resin to bond the fibers together, while the wet process relies on the combination of natural bonding action of the lignin

in the fibers and the contact of the fibers to produce a cohesive panel and a synthetic resin

bond.

Fiberboards are not used generally in loadbearing applications because of their tendency

to creep under load. Also, they tend to be less

stiff than other wood panels of similar density.

Potential Improvements in Fiberboard Manufacture

There have not been many recent developments in the fiberboard field in the United

States, with the exception of MDF, Some efforts have focused on using lower grade raw

materials and hardwoods, but since fiberboard

is not a major consumer of wood raw materials, gains in this area would affect only modestly overall demands on the resource base. In

addition, many fiberboard products have been

replaced partially by vinyl, plastics, aluminum,

and other types of insulation.

MDF was developed in the United States

around 1970, and growth of its manufacturing

capacity and markets has been significant, By

1981, the United States was capable of producing 668 million ft2 of corestock MDF.30 MDF

can be produced using either wet or dry processes, and high-quality MDF corestock for furniture can be made from hardwoods. MDF

probably will be used more for interior paneling and nonstructural uses, such as trim, door

jambs, furniture, and casegoods. However,

when produced with an exterior resin it can

be used for exterior siding on houses,

Present and Future Use and Consumption

of Panel Products

During the last 30 years, the decline in per

capita consumption of wood products (including pulp) was offset partially by the increasing

per capita consumption of plywood and veneer. Per capita use of plywood and veneer

rose from 2.3 ft3 in 1950 to 7.0 ft3 in 1979, Overall consumption rose from 2,2 million tons (airsONatiOna] partic]~oard Association, “1 ndustry Board cawClty by State and Product, ” Furniture Design and Manufacturing

54(3), Mar. 11, 1982.
Ch. II--Solid Wood and Panel Products ● 5 9

dried) to 11.8 million tons. During the same period, use of panel products (including fiberboard) rose from 1.3 million air-dry tons to 10.1

million. Statistics on per capita consumption

of structural panel products, exclusive of hardboard and fiberboard, are not available.

Although conventional plywood probably

will continue for another 10 to 20 years to be

the major structural panel product used in the

United States, the greatest growth in panel

products markets in the past few years has

been in particleboard and MDF (fig. 19).31 In

1979, unveneered structural panel products

(waferboard, OSB) accounted for only 1.5 percent of the demand for structural panels. The

American Plywood Association estimates that

this demand will grow to 6.1 percent by 1984,

and other sources forecast even higher demands, perhaps up to 20 percent. Because of

.——.—— —.

‘ 1 S(!(! [lOt(: 8

the slow housing market since 1978, the apparent consumption of panel products (and most

other wood products used primarily in light

frame construction) dropped. Any resurgence

in the housing market is expected to provide

ample opportunities for growth of structural

panel markets. Moreover, structural panels are

expected to compete strongly with softwood

plywood for most end uses (table 19).

The striking feature of panel products markets has been the displacement of lumber and

plywood by composite panels. Structural panels probably will continue to increase market

shares relative to plywood and may begin to

compete with nonwood materials such as steel,

aluminum, and plastics for some structural

products.

A summary of major technical improvements

is shown in table 20. Improvements in processing efficiency have reduced labor requireFigure 19.— Historical Production of Major Panel Products, 1970-79

25,00(

20,000

15,000

c

o—

o

10,000

5,000

0

Softwood

Particleboard

(million square

Insulating \

board

(thousand tons) \

(thousand tons)

Hardwood

plywood

(million square feet,

\

Med. density

surface measure) fiberboard

\

(million square

feet. 3/4a basis)

I I I 1 ..-. * U● I

1970 1971 1972 1973 1974 1975 1976 1977 1978 1979

Year
60 ● Wood Use: U.S. Competitiveness and Technology

ments, increased productivity, improved qual- already are using almost all the wood wastes

ity control, and helped reduce energy for electricity and heating requirements, a

requirements. Larger panel products mills trend expected to continue.

Table 19.— Plywood End Uses and Their Susceptibility to Penetration by “New” Panels

1976 End-market plywood susceptibility

Millions of Percent of

square feet

New residential construction:

Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Floors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Siding and trim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wall sheathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3,091

2,660

960

505

Total new residential construction . . . . . . . . . . . . . . . .

Repair and remodeling:

Structural additions, alterations, and repairs . . . . . . . . .

Shelving and furniture. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Small building and construction . . . . . . . . . . . . . . . . . . . .

Total repair and remodeling . . . . . . . . . . . . . . . . . . . . . .

Industrial markets:

Products made for sale . . . . . . . . . . . . . . . . . . . . . . . . . . .

Materials handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Plant repair and maintenance . . . . . . . . . . . . . . . . . . . . . .

Repair and wholesale trade . . . . . . . . . . . . . . . . . . . . . . . .

Total industrial markets . . . . . . . . . . . . . . . . . . . . . . . . .

Nonresidential construction:

Nonresidential building . . . . . . . . . . . . . . . . . . . . . . . . . . .

Auxiliary uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Concrete forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Farm building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Total nonresidential construction . . . . . . . . . . . . . . . . .

Other uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7,712

2,333

768

322

3,780

1,688

440

421

381

2,970

1,338

280

807

360

2,785

1,153

18,400

to penetration by “new” panels -

—

total High Medium Low —

16.8 % x

14.5 x

5.2

2.7

x

x

41 .9 ”/0

12.7

4,2

1.7

20.50/o

9.2

2.4

2.3

2.1

16.20/,

x

x

x

x

x

x

x

x

7.3 x

1.5 x

4.4 x

1.9 x

15.1 %

6.30/o x

100.0% 48.20/ o 42.00/ , 9.80/o

-. — —

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 20.—Summary of Major Technologies for Plywood and Panel Product Manufacture

Estimated time scale to

Barriers to significant contribution

implementation (years) — — .

Stage of Effect on

Technology development resource base ———.——.

New pressure nosebar Commercially available Increases ability to peel High capital costs o-1o

design small logs; reduces

number of unpeelable

logs —

Backup torque roller In development Same as above None o-5

Waferboard Commercially available Allows hardwood and None o-5

residue use

Veneer-faced composite

—

Commercially available on Allows hardwood and

——— .—

Requires integration of 10-20- - -

core panels small scale residue use veneer and particleboard facility

Oriented strand board

—

Commercially available

—

Allows use of residue None o-1o — — —

SOURCE Off Ice of Technology Assessment
Ch. II-Solid Wood and Panel Products ● 6 1

Wood Use in Light Frame Construction

Wood Conservation

In general, houses probably are overdesigned, even considering the severe and unusual stresses to which they may be subjected.

Failures are unusual in the wood members, but

do occur at joints and edges. More sparing use

of materials that are designed to provide

strength and stiffness, based on new engineering designs, could improve the efficiency of

wood use. Three areas where conservation of

wood materials is possible are in conventional

construction, framing and attaching assemblies, and substitutions for individual framing

members,

Conventional Construction

Conventional construction techniques commonly waste 3 to 7 percent of the lumber and

plywood used in a home. This waste could be

reduced through new design, and the value of

the waste material could be reduced through

selection of lowest quality and smallest size material required. Door and window framing in

nonloadbearing walls possibly could be eliminated. Proper positioning of framing members, such as joists, studs, and windows and

door framing, could further reduce the 1umber

required. Off-center, in-line joist splicing (replacing overlapping joists over the center beam

or support) could minimize the size and grade

of joist required (fig. 20).

Framing and Attaching Assemblies

Panel assemblies consist of framing and

sheathing nailed or glued together, often in

combination with insulation, siding, and finishing materials. The strength and stiffness of

a panel assembly is greater than the framing

or sheathing alone; assemblies can be engineered so that each component enhances the

strength of the others. Additional development

is probably needed to develop this concept

fully.

Factor construction of engineered panel assemblies has two advantages: 1) it allows the

use of rigid adhesives, which increase the ability of individual pieces to share loads to a

greater extent than occurs with mechanical fasteners or adhesives applied onsite; and 2) it reduces the scrap and shortens construction

time. Factory-made assemblies are of two

types: stressed-skin panels and sandwich

panels.

Stressed-skin panels are made of framing

fastened (usually with rigid adhesive) to a skin,

or sheath. In Germany, stressed-skin panels

using particleboard for skins are used in constructing one- and two-family homes. Stressedskin panels can be made with stringers of 2-

inch dimension lumber with plywood or other

panels bonded to either or both sides to act as

a series of I-beams, Factory-fabricated stressedskin floor panels have been in use since 1965

Figure 20.—Offcenter, In-Line Joint Spacing

w -

,.”

End joints properly located
62 ● Wood Use: U.S. Competitiveness and Technology

and have performed satisfactorily. They have

yielded savings in floor material of 20 to 30 percent compared with conventional methods.

Even greater efficiencies may be possible

using sandwich panels constructed to bear the

loads required on walls, floors, and roofs, Sandwich panels can use plywood or other panel

product facings, and their cores can be made

of a variety of materials, such as foamed plastic, honeycomb paper, or bark. These panels

use about 40 percent less wood than conventional construction,

Substitutions for Individual Framing Members

Some wood products can substitute for individual framing members. Two types of products that use less wood and provide needed

structural strength are engineered wood beams

and trusses.

At least one firm manufactures a wooden Ibeam, which is made with solid softwood

flanges and a plywood web and can be used

as a grider, joist, or center beam (fig. 21). Similar products composed of particleboard or

hardboard webs have been used in Europe for

many years for structural framing of walls,

roofs, ceilings, and floors. These do not use as

Figure 21 .—Wooden l-Beam Construction,

Cross-Section

Flange 4

(solid wood)

—

,

Web (ply

SOURCE Off Ice of Technology Assessment

much wood as a solid wooden beam does and

can be used in place of steel I-beams in light

frame construction,

Trusses, or pieces of lumber joined together

to form framing members, were developed in

Germany as early as 1830. The widespread use

of trusses for roof framing is at least three decades old, Floor trusses, although slower than

roof trusses to gain wide acceptance, now account for a minor portion of floor construction,

Use of trusses to frame whole houses—consisting of floor, wall, roof, and ceiling members,

all joined by truss plates—is a recent development.

Truss framing designs could further reduce

the amount of wood required for construction

and may provide other benefits as well (table

21), Trusses—which are joined with conventional truss plates, plywood gusset plates, or

metal fasteners to distribute forces among

members-increase the structure’s rigidity and

reduce the risk of failure. Truss frames eliminate the need for immediate supports and require 30 percent less structural framing lumber

than conventional construction. A truss frame

system, for example, could consist of an open

web floor system, trussed rafters, and wall

studs tied together into a unitized frame.

Although the use of trusses and panel assemblies or sandwich panels offers many opportunities to increase the efficiency of wood use

in housing, the housing industry is interested

in cost savings, not in materials savings per se.

The truss frame system and panel assemblies

often are simpler and faster to erect on site and

may save labor,32 which can account for over

30 percent of construction costs. Wood materials, on the other hand, account for a much

smaller proportion of construction cost, and

wood products designed to make light frame

construction less costly therefore are more

likely to be accepted if they also are laborsaving. The housing industry historically has

been fairly conservative in adopting new building technologies. Part of this reluctance can be

attributed to the need for building-code recogFramed System, ” no date,
Ch. II—Solid Wood and Panel Products Ž 63

Table 21 .— Benefits of Truss Framing

Economic benefits

●

●

●

●

●

●

●

Labor savlngs

Material savings

Qutck assembly

Faster buyer occupancy

Weather protection of equipment and materials.

good working environment, and security

Adaptable to high-volume processes and inventories

of standard size lumber

Many energy-savings features

Fabrication and erection flexibility:

• Uses existing truss-manufacturing technology

● Can use a variety of truss-fabrication methods and

equipment

● Time flexibility in completing finished buiIdings

• Flexibility in subcontractor scheduling

● Potential for relocatable structures

Design flexibility.

● Engineering design services readily available

● Flexible space utilization from clearspan construct ion

● Variety and flexibility in housing design

Safety and quality:

Increased quality without added cost

Strength through controlled assembly

Strong connections between floors, walls, and roof

Reduced opportunity for human error in construction

Overcomes major weakness of conventional construction (malted Joints)

Meets or exceeds current structural, architectural,

and safety provisions I n model codes

T rar> sfer PI an

nition of new construction products and techniques, but buyer acceptance and resistance of

building labor trades to adoption of new systems probably are also significant factors.

New Uses for Solid Wood Material

Two new wood products could replace concrete, stone, or cinderblock in new home construction: 1 ) the all-weather wood foundation

a n d 2 ] the underfloor plenum system.

The all-weather wood foundation is a plywood-sheathed, stud wall made of preservativet mated plywood and lumber that is at least partially below grade. Watertightness is provided

by a sump in the gravel pad beneath the wood

footing, polyethylene film covering the exterior

of the foundation, and caulking between plywood panel joints. The National Association

of Homebuilders Research Foundation, which

helped develop the all-weather wood foundation, estimates that the system uses 33 percent

more wood than does a typical two-story dwelling built on a cinderblock foundations. .

The underfloor plenum system, designed to

replace the concrete slab now used extensively

in the south, provides a n underfloor area

through which warm or cool air can be distributed throughout the house for heating or air

conditioning, eliminating ductwork, Properly

constructed, the plenum has shown no tendency to rot from excessive moisture or to present insect problems. Because it can be buried,

it does not detract from the appearance of the

home. It is cost competitive with concrete

structures.

The all-weather wood foundation has been

accepted by building-code authorities, and

there is no specific code prohibition against the

underfloor wood plenum. Though both are cost

competitive with conventional foundation

building practices, they have not significant}

penetrated the market. Again, the reason for

this probably has to do with the conservatism

of the building construction industry and buyer

acceptance.

Composites of Wood and Other Materials

In general, the wood industry has not invested much time or resources in developing

products that combine wood with other materials. Since the 1960’s, however, composites of

metal or plastic skins laminated to a wood core

have met a number of industrial uses because

they are strong, durable, and corrosion-resistant, The metal-skinned wood panel has been

used in the past in aircraft, housings, partitions,

truck and trailer doors, train interiors, cabinets

and cases, pallets, and escalator balustrades.

Wood composites also may be combined with

foal insulation for cold-storage facilities. Although composite dimension lumber made

from wood particles that incorporate continuous strands of high tensile-strength glass

fibers have been developed, they have not per-
64 ● Wood Use: U.S. Competitiveness and Technology

formed satisfactorily to date because of tech- of wood and mineral-based products, such as

nical problems that arise when materials with cement boards made from excelsior and

a great deal of difference in stiffness are “mar- cement.

ried. ” Some composite panels are composed
CHAPTER II

Pulp, Paper, and Fiber Products
CHAPTER Ill

Pulp, Paper, and Fiber Products

Summary and Conclusions

Pulp and paper manufacturing is moving

toward the production of higher quality pulps

that require less wood input per ton of pulp and

paper produced. Increased energy costs, increasing raw material costs (for both roundwood and sawmill residues), a market that now

emphasizes printability and other nonstrength

factors, and the availability of immense

amounts of less expensive hardwood timber

have prompted the U.S. pulp and paper industry to consider more energy-efficient and materials-efficient manufacturing technologies.

The adoption of mechanical pulping technologies could reduce the amount of fiber required

to produce a ton of paper from about 2.5 tons

of wood, for the kraft chemical pulping process, to about 1.05 tons for thermomechanical

pulping. With this reduction, it is estimated

that each future increase of 2 percent in pulping capacity would necessitate an increase of

only 1.7 percent in wood fiber feedstocks.1

These potential increases in pulping efficiency

and fiber yield can effectively extend the Nation’s usable wood supply, reducing the likelihood of raw materials shortages and relaxing

the pressures on the shrinking U.S. timberland

base. Expanded use of hardwood species that

are presently underutilized may further extend

the domestic timber supply.

Pulping technologies like organosolv hold

prospects for the industry to become a net

energy producer. The organosolv process may

also permit utilizing hardwood species and obtaining high fiber yields with little sacrifice in

product strength. Such processes are still in the

developmental stages but may be commercially

available in 25 years. Meanwhile, the pulp and

paper industry could reduce the amount of en-

‘G. Styan, “Impa{.t of North American Tlrnber Supply on Innovat ions i n Paper Ttx:hnology, “ pa~}er Tra~~ Journal, VC)I. 164,

May 30, 1980,

ergy required by increasing the use of mechanical pulping and expanding the use of recycled

paper. In addition, the efficiency of chemical

pulping may be increased by adopting pyrolytic

technologies for the recovery of spent pulping

liquor, autocaustisizing to reduce the energy

required in the lime-kiln process, and using anthraquinone as a catalyst for chemical kraft

pulping to increase fiber yields.

Press-drying technology, while still in developmental stages, shows promise for both reducing the amount of energy required in the

papermaking process and enabling the use of

hardwood species not currently used in large

quantities. In some respects, the quality of the

paper produced by this method exceeds that

of unbleached kraft paper produced by conventional processes. It may also afford an opportunity for the U.S. pulp and paper industry to

capitalize on a growing export market in linerboard and other heavy-duty packaging materials.

Advanced research and development (R&D)

on improving the strength and stiffness of paper could lead to development of structural fiber products able to compete with a number

of metallic, ceramic, and plastic materials. In

addition, paper may be combined with other

materials such as plastics, coatings, and synthetic fibers to produce composite materials

with superior qualities.

Although plastics have made significant inroads in certain types of packaging, and have

significantly displaced paper sacks for lightduty uses, paper still commands a major proportion of this market and will probably continue to do so. Moreover, increases in energy

costs could improve paper’s competitive position relative to petroleum-based plastics, which

require larger energy inputs in production. The

paper industry could further strengthen its

67
68 ● Wood Use: U.S. Competitiveness and Technology

competitive position if it continued to adopt

existing energy-efficient technologies.

Electronic telecommunications technology,

on the other hand, could have significant impacts on demand for printing and writing paper in the future. While the magnitude of its

effect on paper is yet uncertain, the introduction of advanced electronic devices such as

electronic filing (the “paperless” office), video

magazines, electronic newspapers, and video

catalogs and directories may increasingly affect the use of paper now and during the next

two decades. Recently, the use of word processors and office copying equipment has increased the demand for paper products, a trend

that may decline as electronic communications

gain increased acceptance in offices. In the

final analysis, the long-term effects of telecommunications technologies on paper requirements are unknown,

Introduction

Profile of the Pulp and Paper Industry

The United States has the largest per capita

paper and paperboard consumption in the

world, averaging more than 600 pounds annually. It is also the world’s largest producer of

paper and paper products, accounting for approximately 35 percent of the world’s total output. The U.S. pulp and paper industry is ninth

in size of tons produced and 11th in gross assets among the domestic manufacturing industries. In 1981, U.S. production of pulp, paper,

and paper products was estimated at $82.1 billion (current dollars).’

Raw Materials

In 1978 the pulp and paper industry used approximately 77 million tons of pulpwood (oven

dried). Forty-four percent of this came from

chips and sawmill residues, which are wood

wastes from the manufacture of lumber and

other solid wood products. About 26 percent

of the pulpwood used in 1978 was hardwood.

(Trends in wood use in the past 40 years have

been toward increased use of hardwood species and increased reliance on chips and sawmill residues.) In addition, the U.S. pulp and

paper industry used approximately 15 million

tons of recycled wastepaper for pulp and paper production in 1978.3

‘IJ. S. Department of (lommerCe, 1982 ]n~~st~ja] uut]~~k

(Washington, D. C.: U.S. Government Printing Office, 1982), p. 39.

‘Joan E. H uher, The A’line Guide to the Paper Industr}r (Fairfie]d, NJ.: (Jharlcs H. Kline & (j{),, 1980), pp. (j6-67,

The pulp and paper industry also uses about

one-quarter ton of chemicals for each ton of

paper or paperboard produced, ranking sixth

among all industries in dollar value of chemical products purchased. It is also the largest

user of water for processing among all manufacturing industries. Finally, the industry is one

of the leading industrial consumers of energy,

using roughly 7,2 percent of the Nation’s industrial energy requirements and 2,8 percent

of the total energy used in the United States.

Approximately half of the energy used by the

industry is produced internally from wood residues and other waste products. Because of the

large energy requirements and the sensitivity

of production costs to energy prices, the pulp

and paper industry has become an industrial

leader in energy conservation and cogeneration (internal generation of electricity from

steam heat),

Product Demand

Demand for paper and paper products is

closely tied to economic growth and disposable

income levels. Although year-to-year fluctuations occur, correlating with economic trends,

the industry is relatively free from the cyclical

variations experienced by other primary industries such as mining, metals, and solid wood

products.

Capital

The pulp and paper industry

ally high capital requirements

has exceptionfor plant and
Ch. Ill—Pulp, Paper, and Fiber Products • 69

equipment, Capital investment currently

ranges from $350,000 to $1 million per installed

ton of daily capacity, depending on a mill’s design and whether the investment is an addition

to the existing mill or a new facility.4 The paper industry invested $6.8 billion in capital expenditures in 1980; however, $369 million, or

5 percent, was spent on pollution control

equipment that did not increase production capacity.’

Industry Size and Production

With over 4,000 firms employing about

626,000 workers, the pulp and paper products

industry is an important component of the U. S.

economy. It produces over 14,000 different paper products, and its potential for developing

new and even better paper and fiber products

in the future is high. At the same t i me, more

efficient manufacturing processes could reduce energy use and lead to increased use of

presently underutilized, but prevalent, hardwood species.

It is estimated that paper products account

for almost three-fourths of the wood-based

sales of the top 40 firms in the forest products

industry.6 While the pulp and paper sector consists of a large number of competing firms, the

10 largest firms manufacture over half of the

pulp, paper, and paperboard products produced in North America. In addition, a number of the major pulp and paper manufacturers

produce a variety of secondary products, including solid wood items, containers, writing

papers, and sanitary paper products (table 22).

Fifteen companies that produce both paper and

sol id wood products are prominent among the

wood-based industries, but together they accounted for only 24 percent of all wood-based

sales in the United States in 1978.7

In 1976, the South produced 67 percent of

the Nation’s wood pulp. Southern forests are

particularly attractive to the industry because

of the abundance of both softwoods and hardwoods, The pulp and paper industry has expanded its capacity in the South in recent

years; while the South’s share of total pulp production was only 48 percent in 1947, it is now

over two-thirds, The West produced 17 percent

of the Nation’s wood pulp in 1976. The remaining 14 percent was produced i n the East and

in the North Central States. B

While pulpmills are located near raw materials, the manufacturing sector of the industry,

which makes containers, bags, sanitary products, and stationery, is concentrated near the

markets. Thus, the New England Middle Atlantic, and North Central States produce 62

percent of all paper products. Much of the

timber resource in these regions is hardwood,

which has not been used extensively for paper

production in the past. Wood pulp production

in these regions currently constitutes only 16

percent of total U.S. wood pulp production.

Uses of Pulp, Paper, and Paperboard

Total U.S. pulp production has been projected to increase from 53.2 million short tons

in 1981 to 54.8 million short tons in 1982. How

ever, the actual volume may be lower as a result of the 1981-82 recession. g In addition to the

domestic products used, approximately 4.3 million short tons of pulp were imported in 1981,

primarily from Canada. Pulp exports totaled

3,7 million tons, most of which was shipped

to Europe, Mexico, Japan, and Korea. The total

53.8 million short tons of pulp used were converted into over 66 million tons of paper and

paperboard. Imports of primary paper and paperboard products were about 8 million tons

in 1981, while exports slightly exceeded 4 million tons,

Wood pulp is converted into a variety of paper products (table 23). The major uses of paper, which accounts for 49 percent of the wood
70 . Wood Use: U.S. Competitiveness and Technology

-“ I

v

K

I
Ch. Ill—Pulp, Paper, and Fiber Products ● 7 1

Table 23.—U.S. Production of Paper and Paperboard

in 1981 and Projected for 1984 (thousand tons)

1981- 1984aPaperboard ... ... ..-.. ., . : 14,558 15,360

Kraft fiberboard ... ... . . 1,067 1,140

Other kraft paperboard ., ... 4,71 7 5,070

Bleached paperboard ., ... ... . 3,926 4,100

Recycled paperboard . 7,070 7,150

Total paperboard ., ... ... 31,33 8 33,020

Paper:

Uncoated free sheet . . . . . . . . . . . . . 7,882 8,720

Coated free sheet and groundwood . 4,951 5,340

Uncoated groundwood ... 1,440 1,540

Bristols and other ... ... ... . 1,530 1,580

Total printing and writing . . 15,803 17,180

Newsprint ... ... . . ... . . . . 5,238 5,730

Unbleached kraft ., . ... ... ... . 3,891 3,760

Bleached regular and industrial . . 1,603 1,670

Tissue ., . . ... ... . . . . ... 4,485 4,730

Total paper ., . . ... ... ... . . . 31,020 33,070

Total paperboard and paper ... 62,358 66,090

aMorgan Stanley estimates

—

SOURCE Thomas P Clephane and Jeanne Carroll Linerboard Industry Outlook

(New York Morgan Stanley & Co 1982) p 25

pulp produced, are for printing and writing papers [50.9 percent), newsprint (16.9 percent),

tissue (14.5 percent), and packaging (17.7 percent). Over 51 percent of U.S. wood pulp production is converted to paperboard (a stiff,

heavy paper). Linerboard, which is kraft paperboard used for boxes, shipping containers, and

packaging, accounted for 46.4 percent of the

paperboard produced in 1981. Overall, packaging materials (both paper and paperboard)

made up 59 percent of all paper and paperboard produced in the United States, and was

one of the most rapidly expanding pulp uses.

Since the price elasticity of demand (the

change in demand resulting from a change in

price) for paper products is generally small, the

recent decline of relative prices has probably

had only a small positive impact on apparent

paper consumption.10 The U.S. Department of

Commerce projects shipments of primary paper and paperboard products to rise at the rate

of 3 percent annually for the next 5 years. Market projections through 1986 suggest a steady

increase in domestic and worldwide demand

1 O(; a ] ~u la t j(j ns 1)F. the K ldd~r, Peilhodj’ Economics G r~up illd ic. ate that the relative price elastic it~’ of demand for paper is

approxi miitely 0.5 percent.

for paper products in general. Demand for primary paper and board products is expected to

be exceptionally strong. Economic factors affecting demands for communications, packaging and shipping papers, and boards, however,

will ultimately determine actual demand levels.

The most promising markets during the ensuing 5 years are expected to be for linerboard

and high-quality printing papers. An increase

of 6 percent in the trend line of 1982 linerboard

exports is forecast by some analysts,ll and the

demand for high-grade printing and publishing papers is projected to increase at an annual

rate of about 7 percent.12 Demand for both

printing paper and linerboard is expected to

expand at rates twice that for products of the

paper industry overall. While domestic consumption will probably increase gradually in

response to a stronger economy, the demand

for exports is expected to increase even more,

in response to expansion of the industrial economies of the People’s Republic of China, Japan,

Malaysia, Indonesia, the Philippines, Taiwan,

and Korea.

Advanced Paper Materials

The development of stiff, durable paper, with

strength characteristics currently achievable

only at the experimental level, offers future

prospects for new structural building products,

Paperboard has been tested for use as sheathing and wall modules in buildings with mixed

results. 13 The effects of moisture on the dimensional stability and stiffness of the paperboard

is a major factor limiting the usefulness of paper as a structural material. New high-strength

papers with protective coatings, coupled with

innovative designs for paper-based structural

materials, are a possibility, But considerable

R&D remains to be done prior to commercialization.

I] Thomas p, C]epha ne and Jeanne Ca rrol ], Linerboard Indus’-

try Outlook (New York: Morgan Stanley & Co,, 1982], p. I Z.

IZCorp~rate Strategies, “A Narrowed Boise Cascade F’ocuscs

on Paper, ” l?usiness il’eek, Apr. 26, 1982, p. 81.

13’’ Emergency Housing for $2,500, ” Technology Re\Fie~t”, Ma\’/

June 1982, p. 86. “Paperboard Houses Now Approved for all Exposures by FHA, ” Paper Trade Journal (Aug. 23, 1971], p. 53;

“Paper Houses Buyers, ” Chemica) Engineering, Sept. 8, 1969,

RP 76-71.
72 . Wood Use: U.S. Competitiveness and Technology

Wood pulp may be converted into paper

products ranging in character from superabsorbent fluffy tissue to extremely hard, boardlike materials. Wood pulp’s versatility results

from the ability to vary paper’s stiffness over

a wide range. Wood fibers are extremely flexible, strong, and durable. When brought into

close contact, they form a durable fiber web

as a result of hydrogen bonds, strong bonds

which provide the strength and stability of paper. Hemicellulose acts as an adhesive between

the fibers and adds strength.

Stiffness is the major quality that makes papers so suitable for boxes, shipping containers,

and, possibly, structural building materials. Although strength is also important, it is more

frequently lack of stiffness that limits the

choice of materials for these products. Because

cellulose fibers attract water, moisture can affect paper’s structural integrity by softening the

fibers and reducing their stiffness, Tests in

modifying paper to enhance stiffness and moisture resistance, performed at the U.S. Forest

Service Forest Products Laboratory (FPL), have

demonstrated that super-strength paper may,

on a weight basis, be capable of matching the

performance of other solid materials like solid

wood, aluminum, and steel.14

The major factors affecting stiffness that are

subject to control by the papermaker are fiber

orientation, density and fiber bonding, and

IAv. setterho]m, ‘ ‘Factors That Affect the Stiffness of Paper,

The Fundamental Properties of Paper Related to Its Uses, vol.

1, F. Bolam (cd.) (London, England: The British Paper and Paperboard Industry Federation, 1976), pp. 253-266.

shrinkage control during the drying cycle. *s

The prospects for improving paper stiffness

through the use of synthetic resin additives are

not considered as promising as improved bonding and fiber orientation in the papermaking

process.

Researchers at FPL hypothesize that an

elastic modulus of approximately 1.5 million

pounds per square inch (psi), with a specific

gravity of 0.4, could be achieved in paper in

which the fibers are parallel and shrinkage is

carefully controlled during drying. This level

of stiffness is approximately equivalent to that

of wood parallel to the grain at the same specific gravity. Laboratory tests have produced

paper sheets of specific gravity of 0.75, with

a tensile strength of 38,000 psi and an elastic

modulus of 3.8 million psi.16 These values substantially exceed the specific strength and stiffness-to-weight ratios of all common structural

materials, including solid wood. Only certain

graphite and boron fiber composites surpass

the strength of this “super paper” at the specific gravity tested. Laboratory researchers

conclude that paper can be produced that is

stiffer and stronger than the wood from which

it is made, If high-strength papers can be developed that are capable of maintaining stiffness and dimensional stability in high humidity, they may be used for a range of structural

applications now being served by wood, plastics, or metals—e.g., housing, furniture, and

containers,

.

IsIbid., p, 266.

lelbid., p. 260.

Role of Paper and Cellulosic Materials in the U.S. Material Mix

Competition with traditional paper commodities for U.S. markets comes primarily from

two areas: plastics and electronic communications. Competition from plastics is often in the

form of substitution of plastic products for

paper products and, occasionally, composite

products made from paper and plastics, Electronic communications, on the other hand,

have the potential for displacing a share of the

paper market by reducing the need for writing,

copying, printing, and business forms. So far,

however, electronic communications has probably resulted in greater consumption of paper,

owing to increased use of word processors,

high-speed computing systems, and inexpensive office copiers.
Ch. Ill—Pulp, Paper, and Fiber Products ● 7 3

The impact of competition from plastics and products, in contrast to linerboard and paperthe electronics media on paper materials will boards used in shipping containers, will be serivary among paper products. Newsprint, writ- ously affected by competition from plastic

ing and printing papers, business forms, paper products and the electronic media. The printbags, and wrapping papers constituted 47 per- ing and writing paper sector, which constitutes

cent of paper consumption in the United States one-third of U.S. paper consumption, will likely

in 1979 (table 24). Some anticipate that these experience the greatest impact from the expanTable 24.—Uses, Grades, Production, and Consumption of Paper Products in the United States in 1979

Apparent

Product ion consumption

Market Grade (thousand tons) Percent (thousand tons) Percent

Newspapers . . ... . . . ... , . ... . ...

Magazines, directories, catalogs . . . . . . . . . . .

Newsprint

Uncoated

groundwood

Coated papers

Uncoated book

4,062

1,530

4,526

7,868

376

125

1,114

3,934

1,791

4,525

29,851

14,076

1,127

4,721

4,023

4,883

31,631

3,466

—

6

2

7

12

<1

<1

2

6

3

11,215

2,254

4,640

16

3

7

11

<1

<1

2

6

2

6

54

18

1

7

5

11

42

5

—

100

Magazines, annual reports, other periodicals . .

Books . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . .

Commercial printing, envelopes, business

forms, Iables, duplicator covers, and text . . Writing and

related

Thin paper

Cotton fiber

7,913

391

126

1,116

Cigarettes, carbonizing condensers . . . . . . .

Bond, writing, other business, and technical .,

Tabulating index, tag and file folder,

post card ... ... . . . . . . . . . . . . . . .

Wrapping, bag, sack, shipping sack . . . . . .

Bleached bristols

Unbleached kraft

packaging and

individual

converting 3,937

Bleached bags, wrapping glassine,

greaseproof ., . . . . . ... , . . . . . . . . . . . . . . Other packaging

and industrial

converting

paper

Special industrial

paper

1.729

Industrial converting . ... . . . . . . . . . . . . . .

Sanitary tissue papers, waxing, and wrapping

tissues . . . . . . . . . . . . . . . .

Total paper ... . . . . . . . . . . . . . ... .

Facing for corrugated or solid fiber boxes . . . .

7

46

Tissues 4,514

37,835

12,611

Unbleached kraft

Iinerboard 22

Tube, can, drum, file folder, shipping

containers . . . . . . . . . . Other unbleached

kraft

fiberboard 2 1,050

Recycled corrugating medium, chip and filler

board boxes, partitions and dividers . . . . . Semichemical

paperboard 7 4,737

Folding cartons, milk cartons, paper plates,

cups, posters . . . . . . . . . . . . . . . . Solid bleached

paperboard 6 3,310

Folding cartons, setup boxes, gypsum

wallboard facing . . . . . . . . . . . Recycled

paperboard 12

49

7,533

Total paperboard ., . . . . . . . . ... . . . . . 29,241

Construction products, insulating board,

binder, and shoe board . . . . . . . . . . . . . . . . . . Building and wet

machine board 5

—

100

3,763

Other . . . . . . . . . . . . . . . . . . . . . . . . . . (462)

Total paper ., ... . . . ... , ... ... , . . . . . . . — 64,947 70.340

SOURCE Adapted from G Boyd Ill and H Dudley, Paper Industry Outlook for 1980 Through 1982, Part // (New York K!dder , Peabody & Co 1980) p 10
74 ● Wood Use: U.S. Competitiveness and Technology

sion of electronic communication if telecommunications technology is accepted by the

business community and home use expands

significantly in the future. Plastic substitutes

for paper bags, wrapping papers, and miscellaneous office supplies could displace 10 percent of the paper consumed in the United

States annually,

Competition From Plastics

The use of low-density polyethylene film

(LDPE) for packaging, wrapping, and sacking,

and high-density polyethylene film (HDPE) for

printing and wrapping paper, is a comparatively recent trend that began during the past decade and continues to expand at a steady rate.

Plastics claimed only a l-percent share of the

grocery sack market (small sacks used for individual items) in 1979, but within 2 years expanded to 5 percent of the market. The plastics

industry projects that plastics could capture as

much as 25 percent of the grocery sack market by 1985,’7 but, according to some analysts,

the penetration of plastics into the traditional

kraft paper markets will probably be selective,

For example, the grocery bag market (larger,

multiwalled, heavy-duty bags) may be less vulnerable to inroads by plastics, at least during

the intermediate term (10 to 15 years).l8

Several factors will determine the future

competitiveness of plastics in relation to paper products: 1) relative production costs, including raw material (resin for plastics and

wood, and chemicals for paper), labor (in general, the paper industry is more labor-intensive), and energy consumption; 2) rate of technical innovation; and 3) consumer acceptance.

Sack/Bag Market

Plastics’ share of the merchandise bag market was estimated to be 35 percent in 1981, an

increase of 10 percent over the previous year,

Investment analysts at Morgan Stanley & Co.

estimate that plastic bags will control 60 percent of the merchandise bag market by 1985.19

“Clephane, p. 18.

InIbid., p. 17.

lgIbid., p. 16.

Production of 275,000 tons of finished bags annually account for only 5 percent of the total

production of unbleached kraft paper. Morgan

Stanley estimates that by 1985, merchandise

bags will require no more than 3 percent of the

total production of unbleached kraft paper production.

Large grocery bags consumed 12 percent

(467,000 tons) of the unbleached kraft paper

produced in 1981, Small grocery sacks accounted for 95 percent of the 1.3-million-ton

total grocery sack market in 1981 and used approximately 34 percent of the unbleached kraft

paper produced during that year. Until recently, plastics were not considered to be serious

competitors of kraft paper for the grocery bag/

sack market; however, some analysts now predict that plastics may be able to capture rapidly

an increasing and significant share of the market, The paper industry confirms that plastics

now compete at prices ranging from $0,029 to

$0.031 per sack and sell for 10 to 15 percent

less than unbleached kraft sacks. The major

plastic sack producers include several oil companies and chemical companies: Mobil, Exxon,

and Union Carbide,

One reason for plastics’ current success in

competing with kraft paper in the bag and sack

market is the availability of low-cost resins.

Another is technological developments in polyethylene that permit substantial reduction in

plastic thickness and volumes without sacrificing strength. For example, development of the

Unipol process for making linear, low-density,

polyethylene resin in 1979 constituted a major breakthrough for the plastics industry because it required considerably lower capital investment and consumed less energy per unit

of resin produced.

Paper currently possesses properties that are

superior to plastics as a material for bags and

sacks. The rigidity of paper sacks enable them

to stand freely for filling in grocery and retail

stores. To compensate for lack of sidewall rigidity, plastic sacks must be mounted in racks

for ease of filling. Although such technology

does not yet exist, it might eventually be possible to develop a rigid-wall plastic sack capable of competing economically with paper
Ch. Ill—Pulp, Paper, and Fiber Products ● 7 5

sacks. The conversion from LDPE to newer

low-density polyethylene film could provide

even greater price advantages for plastic

sacking.

Multiwall Sacks

One major segment of the paper sack market that has not yet been seriously challenged

by plastics is the multiwall, bulk shipping sack.

Plastics have not made significant inroads in

this sector because the strength properties required put plastics at a cost disadvantage relative to kraft paper. Plastics currently occupy

10 percent of the multiwall sack market, and

some industry analysts assume that this market penetration will remain stable over the long

term unless unforeseen technological developments occur. Product developments in the pulp

and paper industry may reinforce paper’s share

of the multiwall sack market. For example, St.

Regis Paper Co. recently introduced Stress

Kraft, a superior-strength paper permitting a

20-percent reduction in the weight of the paper used for multiwall sack construction.20

Multiwalled sacks consumed approximately 26

percent of the unbleached kraft paper produced in 1981.

Liquid Containers and Packaging

Plastic containers for liquid

nificant gains in competition

have made sigwith glass and

coated-paper containers. Plastic l-gallon milk

containers now dominate the market, although

most smaller l-quart and l-pint containers continue to be coated paper. Technological innovation accounts for the current inroads of plastics

in the packaging sector, yet plastics have still

captured only a small proportion of the packaging and container market. Because plastics are

petroleum derivatives that are not biodegradable, and in some cases may produce toxic

fumes if incinerated, plastic packaging products have met opposition from environmentalists. 21

The market for tissue wrapping papers and

glassine and parchment papers has not been

significantly penetrated by plastics, although

plastic bakery bags and cereal box liners are

in wide use, The major limitations to the use

of plastics in these areas are primarily linked

to the difficulty of adapting automatic packaging machines for the new materials. HDPFs

have properties similar to the cellulose films

and may some day challenge conventional paper materials in this area.

While plastic and aluminum foil trays have

significantly challenged paperboard fiber trays

for packaging meats, fish, and prepared and

frozen vegetables, recent trends in microwave

cooking (which cannot use aluminum foil containers and requires heat-resistant receptacles)

have resulted in a new generation of oven-resistant packaging. Polyester coatings have been

joined with molded paper trays to create a composite product suited for microwave cooking

conditions. 22

A number of composites, which combine paper with plastics and metals, provide a product superior to those made with one material.

Among these are collapsible plastic bags inside

paperboard cartons equipped with a spout for

dispensing liquids, thermoplastic-coated paperboards for water-resistant food containers,

paper meat trays coated with plastics, paperboards treated with clay-adhesive mixtures and

bonded with metal foils, and paper cartons

laminated with plastic foams.

Printing and Writing Papers

Plastic films have not significantly displaced

printing and writing papers, except for specialized uses. The properties of paper (printability,

flexibility, wearability, and price) are well

suited for printing, recordkeeping, business

forms, magazines, and books. The durability

of plastics (e. g., in Mylar and waterproof papers) makes them useful for transparent reproducible graphics, children’s books, and outdoor

use, However, the cost of printable plastic films

is approximately twice that of the highest

‘z~lr, l,onl~ i re, 4’ I’al)crboar(l Packages fOr ot’ens,’” Fm[i Ellgl

neering, ]an~]ary I $)78, [). 62 ,
76 ● Wood Use: U.S. Competitiveness and Technology

grades of paper.23 Paper industry analysts believe the probability is low that plastics will be

able to displace paper in general business and

commercial use, except for the highly specialized applications named above.

Synthetic Fibers

The major petroleum-based synthetic fibers

that compete with rayon and acetate are the

polyesters, nylons, acrylics, and olefins. In

1968, the worldwide volume of cellulosic manmade fiber produced was about the same as

that of noncellulosic manmade fibers (3.9 million tons).24 Since that time, the noncellulosic

fibers have dominated the artificial fiber market. This trend may continue, although the market shares for rayon and acetates appear to

have stabilized. Some predict that a slight resurgence in the use of rayon may occur if petroleum prices increase significantly.

Improvements in the viscose rayon process

or the development of new processes that could

reduce the cost of rayon manufacture may also

reinforce the market position of cellulosic products. Some claim that the rayon industry has

suffered from a reduction in R&D in the 1950’s

and 1960’s, the period when petroleum-derived

synthetics displaced rayon as the predominant

manmade fibers.

The rayon and acetate industries, however,

consider their major competitor not to be the

petroleum synthetics but natural cotton fibers,

Cotton and rayon have similar properties with

regard to moisture absorption and other wear

characteristics, making possible development

of improved, cottonlike rayon fibers that are

directly substitutable for cotton. The rayon industry sees an opportunity to expand its market without meeting competition from petroleum synthetics, based on the forecast that

worldwide demand for cotton will increase at

———-— —

“’(Where Plastic Papers Stand in Printing, Bags and Tissues, ”

Modern Plastics, March 1973, p. 55.

Z4Committee on Renewab]e Resources for Industrial Materials

(CORRI M), Fibers as Renewable Resources for Industrial Materiais [Washington, D. C.: National Academy of Sciences, 1976],

p. 234.

a rate exceeding the capacity of the agricultural

industry to meet the requirements. ’s

Competition From Electronic Technologies

Recent developments in large-scale, integrated circuitry are revolutionizing the communications and information fields by reducing the size of computers and microprocessors,

expanding their capacities and flexibilities, reducing costs, and increasing availability to a

wider range of potential users.26 Through the

use of satellite communications, microwave,

and interfacing devices on home television receivers, electronic communications may be

linked with large centralized information systems that are capable of providing a wide range

of user services. Further developments in optical digital-disk technology (a specially coated

plastic disk on which information is encoded

by a high-powered laser beam) may enable the

permanent storage and relatively cheap retrieval of immense amounts of information.27 Fundamental research on new concepts of data

storage and retrieval may pave the way in the

future for even greater expansion of information technology.

Achievements in telecommunications technology during the past two decades offer a

number of opportunities for improving the

speed and flexibility of communications, Electronic mail is being considered by the U.S.

Postal Service and private firms as a way to

speed textual communications and eliminate

the need for handling and physically transporting mail.28 Some foresee electronic filing leading to the paperless office.29 Video magazines,

which may be transmitted directly into the

Z5c; . DaU], op. Cit., P, 84’

z6LJ.S. congress, office of Technology Assessment, COmputerBased National Information Systems: Technology and Public

Policy’ Issues, OTA-CIT-146 (Washington, D. C.: U.S. Government

Printing Office, September 1981), pp. 3-12.

“C. Goldstein, “Optical Disk Technology and Information, ”

Science, vol. 215, Feb. 12, 1982, p. 862.

“J, Free, “Electronic Mail: Good-bye to Paper?” Popular

Science, September 1980, pp. 78-141.

‘

e

’’ Electronic Filing to Threaten Cut Size Paper Markets, ” Fiber Market News, No. 72, Dec. 14, 1981, p. 1,
Ch. Ill—Pulp, Paper, and Fiber Products ● 7 7

home via satellite and conventional television

receiver, are in the early stages of development.30

Television-adapted versions of the phone directory, retail catalogs, and other merchandising devices, which can be viewed on home televisions, are currently being evaluated for

public use. 31 Also, a number of major newspaper publishers are interested in producing electronic newspapers; in the United Kingdom at

least three such teletexts are already operating.32 Futurists consider as long-range prospects the use of vast central information systems—’’hypertex capableable of retrieving, displaying, and manipulating information from

“grand libraries” through personal consoles. 33

Such broad-scale application of electronic

communications could affect dramatically the

use and demand for paper in the future. Although telecommunications has experienced

rapid growth during the past decade, its application for office and home use is still in its infancy, Thus, uncertainties regarding the rate

of commercialization and public acceptance

and forecasts of its impacts on paper must be

considered speculative. While there is little

disagreement among analysts that electronic

communications may ultimately displace the

need for some writing and printing papers, the

timing and extent of the impacts are subjects

of debate.

Euro-Data Analysts, a British-based market

consulting group specializing in the paper,

board, and packaging industry, forecasts a major shift from the use of paper toward increased

reliance on electronic media.34 Over the long

term, Euro-Data considers it likely that the developed countries will achieve a nearly paper30’’Tips on Tiipe: (;assette Magazines Arrive, ” Time, June 14,

1982, p. 78.

314 ’ Paper Chases the EIectroni{; Age, ” Bosjness Week, Apr. 5,

1982, pp. 112-115,

32K. Edwards, “The Ele(;tmnic Newspaper, ” Communications

Tomorrow (Bethesda, ~ld,: World Future Society, 1981), pp.

54-59.

“H. Freedman, “Paper’s Role in an E]ec,tronic World, ” Communications Tomorrow’ (Bethesda, Md,: World Future Society,

1981), pp. 60-65.

34Eu rO-DataAnalyst S, The Impact of Communications Technologies on llemand for Printing and Writing Papers (Ashtead,

Surrey, U. K.: Euro-Data Analysts, 1980),

less society as the rate of commercialization

of electronic communications accelerates. Euro-Data forecasts that during the current decade, paper will lose a share of the market to

the electronic media through video telephone

directories, office communications, telex, video

books, video newspapers, consumer magazines, and electronic funds transfers.

The American Paper Institute (API) sees immediate competition with the electronic media

in electronic fund transfers, office reproductions that require less paper, electronic mail,

and electronic storage and microforms .35 Beyond 1985, API anticipates competition developing in direct-mail advertising; voice message

systems that would reduce the requirements

for envelopes and business forms; expanded

use of home video catalogs and directories;

video publication of periodicals; interactive

videotext, which might reduce book publishing; and video systems displaying time-critical

news, which could displace some newsprint.

By 1995 and beyond, portable handheld video displays could displace printed magazines,

books, and newspapers (table 25). API notes

that the electronic media accounted for over

60 percent of the total communications expenditures during the 1970’s. If the trend continues, its share could exceed 70 percent by the

year 2000, while the paper-based media’s share

may drop to less than 30 percent. 36

Other analysts agree that electronics technology will probably reduce the demand for printing and writing papers during the next decade,

International Resource Development, Inc.

(IRD), a technology consulting firm, sees home

video as potentially flattening the growth in demand for paper directories and catalogs within

6 years.37 IRD projects that by 1991, electronic

filing could reduce demand for office paper by

300,000 tons per year (5 percent of current office consumption). Data Resources Inc. (DRI)

estimates that home video systems could start

affecting newsprint demand by 1985.38 If elecssAmerican Paper ] n st itute, Information Technolog~’ and paper Demand (New York: API, 1981], p. 52.

j~Ibid

“’’Paper Chases in the Electronic Age, ” op. cit., p. 112.

‘eIbid.
78 ● Wood Use: U.S. Competitiveness and Technology

Table 25.—New Information Technologies and Their Potential Impact on Paper Construction

Paper end-use categories/relevant information techniques Paper end-use categories/relevant information techniques

Commercial business and printing papers:

. Printing papers.”

—Advertising: direct mail— Home video information (videotex and teletext) may open new avenues for advertising and could thereby adversely impact print-based advertising, including direct mail. Timeframe: beyond 1985.

—Printing: financial and legal— Expanded use of word

processors and intelligent printer/copiers will encourage

more in-house production of forms. Electronic funds

transfers will continue to grow, subtracting from the use

of printed forms in financial transactions.

● Office graphic reproduction —Growth i n the use of intel -

Iigent copier/printers will encourage more in-house offset

printing. Timeframe: currently taking place; trend is expected to continue.

Duplexing and reduction capabilities, both of which operate to conserve paper, will become common features of

office copiers, including those positioned at the low end

of the price scale. Timeframe: currently taking place; trend

is expected to continue.

Converting papers:

●

●

●

✎

Envelopes- Expanded use of electronic mail and voicemessage systems may hold down the number of envelopes

used by businesses and individuals. (Voice-message systems are not expected to come into widespread use before

1985.)

Business forms—An increased proportion of business

forms will be produced in-house using intelligent copierprinters. Electronic storage and microforms will continue

to displace paper forms in selected applications.

Stationery and tab/et—A modest, negative impact from

electronic mail, electronic pads, and voice-message systems appears possible. Timeframe: beyond 1985.

Magazine publishing: Modest, negative impact possible from

home video information. The future development of a fullpage portable display for reading electronically stored information could also impact paper consumption by magazines. (The advent of portable displays is not anticipated

until the 1985-95 timeframe, or beyond.)

Other periodical publishing: Home video information may

hold down paper consumption for catalogs and directories. The future use of videodiscs as a storage medium

for reference materials may have a negative influence on

paper consumption for catalogs and directories. Timeframe: beyond 1985.

Book publishing: Possible use of home and office videodiscs

to store large quantities of infrequently examined information could limit future demand for reference books

such as encyclopedias. Interactive videotex may Iikewise

have a negative influence on the demand for reference

books. Timeframe: beyond 1985.

As noted above, next to magazines, the advent of a portable, full-page display possessing adequate image quality

for prolonged periods of reading may lead to reductions

i n the demand for paper-based, printed materials, including books. Timeframe: 1985-95, or beyond.

Computerized printers reduce the need for special labels

in certain applications.

Newspaper publishing: Home video information may draw

classified advertising and financial listings away from

newspapers. It may also compete with newspapers by

becoming an efficient transmitter of time-critical news information. Timeframe: beyond 1985.

Advent of compact display could also have repercussions on newsprint consumption. Timeframe: 1985-95,

or beyond.

SOURCE American Paper Institute, Information Technology and Paper Demand (New York, API, 1981), pp 10-11

tronic media affect newspaper advertising as

television has, by 1995 they could displace

800,000 metric tons (tonnes) of newsprint annually (15 percent of current U.S. production),

In the short term, demand for writing and

printing paper seems to have increased with

the proliferation of word processors and office

copiers, which enable fast and inexpensive

copies of texts and graphics to be made, Although this phenomenon is considered by

some industry analysts to be temporary, others

forecast that paper will continue to dominate

office communications, magazines, and newspapers.39 However, both International Business

Machines (IBM) and American Telephone and

Telegraph (AT&T) have stepped up activities

in the field of information storage and transmitSQFree~ rn~ n, op. (: it., P. Go.

tal, and some analysts consider their entry into

the market as the harbinger of rapid progress

and expansion in electronic communications. M

With 30 percent of U.S. paper production being used for storage and transmission of information, the short-term trend in increased paper usage as a result of electronic office

equipment is expected by some industry analysts to give way to sharp decreases in paper

use during the next 20 years .*1

The future impact of electronic media on paper demand may depend on its effects on the

attitudes of a generation of children accus40(;. 11 rown, “Tomorrow in the Pulp and Paper Industry: An

Outsider’s v’iew, ” speech to 1982 Annual Employee Regulations

Conferen(;e of the American Paper Institute and Fiber Box Association, St. Louis, Me., ]an. 27, 1982 (New York: Kidder Peabody’

and Co., Inc., 1982), p. 4.

41 ibid.
Ch. Ill—Pulp, Paper, and Fiber Products . 79

tomed to the partial substitution of electronics

for paper. While many older people, not so accustomed, find acceptance of nonprinted media difficult, the present school-age generation,

who use nonprinted communications throughout their educational careers, will accept electronic communications for business and home

use more readily. In addition, although current

technology limits the use of electronic communication to desktop consoles and large computer and wordprocessing installations, the development of handheld portable devices with

readable screens—and microelectronic processors capable of storing entire books and magazines—could have a significant impact on the

substitution of electronic media for print.

Pulp, Paper, and Cellulose Fiber Manufacturing

Paper was supposedly invented in 105 A.D.

by Ts’ai Lun, a member of the Chinese imperial

court. 42 Ts’ai Lun’s method for papermaking

involved soaking tree bark, hemp, rags and

other cellulosic materials in water to soften

them and then beating the softened material

until the fibers separated and swelled. He dispersed the fibers in a wet suspension and

formed a thin sheet that was transferred to a

felt cloth and pressed. The resulting web was

dried in the sun.

Paper is still made by essentially the same

process: 1) pulping, to separate and clean the

fibers; 2) beating and refining the fibers; 3) diluting, to form a thin fiber slurry, suspended

in solution; 4) forming a web of fibers on a thin

screen; 5) pressing the web to increase the density of the material and remove excess liquid;

6) drying to remove remaining moisture; and

7) finishing, to provide a suitable surface for

the end use. The three methods for pulping

wood and other cellulose materials include

chemical pulping, mechanical pulping, and

semichemical or chemimechanical pulping—a

combination of the first two methods.

In mechanical pulping, wood chips from debarked logs are ground, or are passed through

a mill, and in some versions of the process are

treated with high-pressure steam (thermomechanical) to separate the individual fibers,

which can then be formed into sheets of paper. Mechanically separated fibers contain lig4zF, F, Wa ngaa rd, WOOd: lfs Structure and properties ((] nl ~’ersity Park, Pa.: Pennsylvania State Uni\’ersity, 1981), p. 335,

nin, which makes them remain stiff, bond poorly, and yellow with age.

Chemical pulping is done by cooking wood

chips in acid, alkaline, or neutral salt solutions

under pressure and high temperatures, which

breaks down the wood structure and dissolves

some or most of the lignin and hemicellulose

contents. Delignification by chemicals causes

the individual fibers to become flexible and increases contact and binding among the fibers

forming the paper mat, thus increasing the

strength of the paper. Semichemical and chemimechanical pulping first breaks down the

wood chemically, then by grinding.

The range of commercial pulping processes

currently used by the pulp and paper industry

is shown in table 26. Nearly three-fourths of

the wood pulp is produced by the kraft process (fig. 22).

Mechanical Pulping

Commercial Mechanical Pulping Technologies

There are four basic mechanical pulping

processes: 1) stone groundwood pulping, 2) refiner mechanical pulping, 3) thermomechanical pulping, and 4) the recycling of paper. Flow

diagrams of the three mechanical pulping processes are shown in figure 23. Mechanical pulping is generally used with softwoods because

of the added strength imparted by the long fiber length of softwood species. Mechanical

pulps are used principally to manufacture

newsprint, printing papers, and tissues that do

not require high-strength paper. Secondary
80 • Wood Use: U.S. Competitiveness and Technology

Table 26.—Major Commercial Wood-Pulping Methods, Grades of Pulp, and End-Products

Pulp grades

Chemical pulps:

Sulfite pulp . . . .

Kraft sulfate pulp

Dissolving pulp

Percent yield per

Wood type dry weight of wood End-products, utilizing grade

. . . . . . . . . . . . . . Softwoods and hardwoods 53-56b

I

c

45-50a’

d

. . . . . . . . . . . . . Softwoods and hardwoods 40-50a

52-53b

. . . . . . . . . . . .Softwood 33-35

Semichemical pulps:

Cold-caustic process . . . . . . . . . . . Hardwoods and softwoods 80-95

Neutral sulfite process . . . . . . . . Hardwoods 70-80

Mechanical pulps:

Stone groundwoode . . . . . . . . . . . . Softwoods 95

Refiner mechanical (RMP)e . . . . . . Softwoods 95

Thermomechanical (TMP)e . . . . . .Softwoods 95

Fine and printing papers

Bleached—printing and writing

papers, paperboard. Unbleached—

heavy packaging papers,

paperboard

Viscose rayon, cellophane, acetate

fibers, and film

Newsprint and groundwood printing

papers

Newsprint and groundwood printing

papers

Corrugating medium

Newsprint and groundwood printing

papers

Newsprint and groundwood printing

papers —

aBleached pulps made from softwoods

bun bleached pulps made from softwoods.

cUnbleached pulps made from hardwoods

dBleached pUIpS made from hardwoods

‘For paper and board

SOURCE George H Boyd Ill and Chad E Brown, Paper /r?dusfry. Ouf/ook for Market Pu/p (New York Kidder, Peabody & Co , 1981), p 5

Figure 22.— Proportions of Woodpulp Produced

by Commercial Pulping Processes

Unbleached kraft

380/o

Sulfite

40/0

\-- ’

Ground wood

90/0

uses include wallpaper and paperboard. Recycled pulp is used mainly for the manufacture

of folding boxboard (grayboard), tissue, corrugated board, and newsprint.

In the stone groundwood (SG) process, debarked short logs (roundwood) are fed whole

into grinders. The abrasion of the grinding

wheel against the wood physically separates

the wood fibers. The grinding process usually

is automatic and continuous, although sometimes it is semicontinuous, Refiner mechanical pulping (RMP) uses chips in lieu of roundwood and produces paper with higher strength

than conventional groundwood because of less

damage to the fibers in the pulping process, A

wider range of species, including hardwoods,

can be processed by the refiner pulping

process.

The most advanced commercial mechanical

pulping system is the thermomechanical process (TMP), which was developed as a modification of the RMP process. In TMP, wood chips

are steamed for several minutes under pressures ranging from 4 to 45 psi and subsequently

refined in one or two stages.

Recycled pulp is manufactured from wastepaper, which is processed into paper stock for

further use in making paper. A small proportion of the paper stock (5 to 10 percent) is deinked, usually with caustic, soda-based chemicals. Most recycled paper, however, is pulped

without de-inking. Pulping is accomplished

through violent agitation and shearing action

82 ● Wood Use: U.S. Competitiveness and Technology

Figure 24.—Wood and Energy Flows in Mechanical Pulping Mills in Conjunction

With Recycling

t

waste paper I

I

I

I 400 Ibs , ~

310 Ibs

wastepaper I

I

I

of kraft pulp to improve its wet strength and

processing on the paper machine. While paper

using TMP consumes 11 to 13 percent less

chemical pulp than ordinary newsprint, improved materials efficiency is gained at the expense of higher energy consumption. When the

cost of energy is considered as well as the cost

of wood, TMP is actually more costly than SG.

Pulp yields from all the mechanical pulping

processes typically are near 95 percent recovery, which is a higher yield per unit of wood

than with the chemical pulping methods. The

principal variables that influence the choice of

mechanical pulping methods are: 1) furnish

(raw material) requirements or wood species,

2) pulp strength, 3) expected gross energy consumption, and 4) expected net energy consumption.
Ch. III—Pulp, Paper, and Fiber Products ● 8 3

The process variables that affect the quality

of mechanically produced pulp are listed in

table 27. Increases in paper strength are gained

by increases in energy consumption, but brightness and opacity, qualities that affect the use

of paper for printing, are largely independent

of the pulping process. Recycling can effectively reduce the consumption of both wood raw

material and energy when used in conjunction

with other mechanical pulping processes.

However, it does so at the sacrifice of some paper strength.

Improvements in Mechanical Pulping

Technical improvements in mechanical pulping have largely been directed at reducing

energy consumption and improving the quality

of mechanical pulps. Pulp yield is approaching

the practical upper limit, since all of the lignin

and most of the hemicelluloses remain in the

fiber, and fiber recovery from mechanical pulping is frequently twice as high as that from

competitive chemical pulping. By reducing

energy costs, mechanical pulping has remained

cost competitive, and improvements in paper

quality have enabled mechanical pulps to displace some of the more costly, higher quality

pulps produced by chemical processes. As

noted in table 27, although improvements in

quality result in some increases in the consumption of energy, the higher quality pulp

produced more than offsets the higher costs of

energy.

Three major developments in mechanical

pulping technologies show promise for improving pulp quality and/or reducing energy consumption: 1) pressurized groundwood (PGW)

pulping, 2) chemithermomechanical pulping

(CTMP), and 3) hardwood chemimechanical

pulping (CMP). Each of these new processes

has reached some stage of commercialization.

A fourth major development is waste-heat recovery.

PRESSURIZED GROUNDWOOD PULPING

In PGW pulping, debarked logs are fed to the

grinding wheel through a heated, pressurized

chamber. The heat and pressure help separate

the fibers, breaking down fewer fibers in the

grinding process and improving pulp quality.

The longer fibers give the end product a higher

tear index than paper made from SG, but it is

slightly inferior to that of TMP. The tear resistance for PGW pulp is 5.6, compared with 3.9

for SG and 7.1 for TMP (table 27), The tensile

index for PGW pulp (35) also lies between that

for SG pulp (32) and TMP (37). In addition to

improved strength, PGW promises some reduction in energy consumption. It is estimated that

the energy requirement may be reduced by 40

percent from that required for the thermomechanical process, or from 1,833 to 2,417 kWh/

ton of pulp to approximately 1,100 to 1,450

kWh/ton. 43

43 C;, \V. E\ans, “Pressured Process for Grounciwoo[] Pr{jdl]( -

tion Making Health~’ Progress, “ })ujp a~]d }~a[}(~r, [’()] 54. 1980,

pp. 76-78.

Table 27.—Summary of Process Variables for Mechanical Pulping (based on the production of 1 ton of ovendry pulp)

Process

Ground wood Refiner mechanical Thermomechanical

Variable pulping pulping pulping Recycle

Furnish type . , Debarked logs Residual chips, Residual chips, Waste paper

sawdust sawdust

Furnish requirements . . . . . 2,100 lb 2,100 lb 2,100 lb 2,200 lb

Energy requirements (kWh/ton) . 1,340-1,790 1,800-2,400 1,800-2,000 360

Strength:

Burst . . . . . . . . . . . . . . . 1.4 1.8 2,0

Tear . . . . . . . . . . . . . . . . . . . . 3.9 5,7 7.1

Tensile, . . . . . . . 32.0 35.0 37.0

Other:

Brightness . 60.0 57.0 57.0

Opacity . ., . 95.0 95.0 94.0
84 ● Wood Use: U.S. Competitiveness and Technology

By 1980, five mills worldwide had installed

PGW systems. Fifteen more plants have been

ordered, including four to be located in the

United States. Some industry analysts consider

PGW technology to have significant potential

for reducing mechanical pulping energy requirements and for displacing some high-quality chemical pulps in the manufacture of newsprint and other printing papers.

CHEMITHERMOMECHANlCAL PULPING

CTMP involves treating softwood chips with

mild sulfite solutions prior to pulping. This

“sulfonation” treatment results in paper with

higher tear indices than do TMP, RMP, or SG

pulping processes.44 Energy consumption for

CTMP may range from 1,360 kWh/ton to 2,000

kWh/ton, depending on the strength of the

sulfite solution. Thus, energy consumption of

CTMP lies within the range of SG pulping, is

less than that required for RMP or TMP, and

results in a higher quality paper. Pulp yields

decrease slightly to between 85 and 95 percent

with CTMP, but these yields are still large compared to chemical pulping and to mechanical

chemical pulp blends. Some TMP pulpmills

have begun to add sulfite chemicals in their

operations to improve pulp quality and reduce

energy consumption.

HARDWOOD CHEMIMECHANICAL PULPING

Mechanical methods for producing pulp

from underutilized hardwood species involve

pretreating hardwood chips with hydrogen

peroxide or sodium hydroxide and processing

them like RMP. Both poplar [softwood) and red

oak (hardwood) have been pulped successfully

by these techniques. However, fiber recoveries

are lower for hardwood CMP than for softwood CMP. Pulp recoveries of 80 to 85 percent

have been reported for poplar, 90 to 95 percent

for red oak.

Energy consumption for CMP ranges from

500 to 1,500 kWh/ton using hydrogen peroxide for chemical pretreatment and 700 to 1,100

.44~ Atack, et ~]., “Sulphite Chemimechanical Refiner PulpAnother Option for Newsprint, ” Pulp and Paper, vol. 54, 1980,

Pp. 70-72.

kWh/ton using sodium hydroxide.45 Hardwood

CMP consumes significantly less energy than

do either SG or other chemimechanical hardwood pulping technologies.

Pulp and paper technologists expect hardwood CMP to expand significantly during the

next 10 to 25 years because of the large volumes

of inexpensive hardwood available, a phenomenon that could have a profound impact on the

utilization of presently underutilized species

such as poplars, red alder, and American sycamore that are abundant throughout the Eastern United States. Pulp produced by hardwood

CMP can be used to produce newsprint and

printing papers. Two small U.S. mills, which

range in capacity from 200 to 250 tons of pulp

per day, have already installed CMP systems

to process hardwood species.

WASTE HEAT RECOVERY SYSTEMS

Mechanical pulping systems create a large

amount of frictional heat during the grinding

and refining processes. Heat recovery systems

that enable use of waste heat (for drying paper, space heating, and water treating) are important to the reduction of energy costs in the

pulping process. Such systems are particularly

important in TMP, which requires large quantities of mechanical energy and produces highquality heat (i.e., high heat under temperature

and adequate pressure) .46 Because of the higher

temperature of waste heat from TMP processes, a higher percentage of usable waste heat

can be recovered from TMP than from conventional groundwood pulping,

Heat recovery technologies currently recapture 3 million to 5 million Btu/ton of pulp produced.” For mills consuming 1,800 to 2,400

kWh/ton, 95 percent efficiency in heat recovery

would represent a total of 5.8 million to 7.8 mil45J, D. Sinkey, ‘lCMP and C’I’MP-A Review,” paper presented

at Forest Products Resear[;h Society Conference, St. Paul, Minn.,

1981.

4EP, J. Walker and E, J. 13atsis, “Heat Recovery From TMP Operations Results in linergy Consert’ation, Pulp and Paper, vol.

52, 1978, pp. 146-148.

‘T’rhe Fossj) ~’nerg~, ~’onser~,atjon Potential Associated W’iih

Producing Wood Pr’oducts From Managed Stands (Bellekwe,

Wash.: Envirosphere Co., 1981).
Ch. Ill—Pulp. Paper, and Fiber Products . 85

lion Btu.48 With current technology, the industry captures 50 to 65 percent of the theoretically recoverable waste heat, Widespread

adoption of these efficient systems has not yet

occurred because of the problems of retrofitting and high capital costs.

Future Prospects for Mechanical Pulping

The three major new mechanical pulping technologies—PGW pulping, CTMP, and CMP—

have improved pulp quality and reduced energy consumption compared with conventional groundwood processes. The resulting higher

quality mechanical pulps will displace the kraft

pulps that are currently mixed with mechanical pulps to improve paper strength. For example, the shift from SG pulping to TMP displaced 300 pounds of kraft pulp per ton of

newsprint. Use of the new technologies will

further reduce the amount of kraft pulp required in newsprint and printing papers, reducing the demand for softwood timber because the pulp yield from these processes is

nearly twice that of kraft processes.

The configuration of mechanical pulpmills

for newsprint manufacturing will likely change

significantly during the next 10 to 20 years.

By employing CMP and CTMP technologies,

using a higher percentage of hardwood as raw

material, and installing highly efficient heat

recovery systems (85 percent recovery), the mechanical pulpmill of the future could reduce

its heat requirements by 1.0 million Btu [300

kWh/ton of heat) and reduce electrical energy

consumption by 97o kWh/ton of newsprint

from that currently required by TMP mills.

Savings of this magnitude of purchased electric power is equivalent to a savings of 11 million Btu of heat input at the powerplant. In addition, 3.5 million Btu of usable heat could be

recovered, offsetting over 50 percent of that

currently required in the pulp and papermaking process.

Further improvements in energy efficiency

and wood utilization could result if a recycle

pulpmill were integrated with either SG or

TMP pulpmills (fig. 25). The practical upper

limit of recycled fiber in the pulp mix is estimated to be about 40 percent. A small proportion of kraft pulp is required in the mix to

strengthen the newsprint if larger proportions

of recycled pulp are used.49 The major gains

in energy efficiency between a wholly roundwood C M P or CT M P mill and one integrated

with a recycle pulpmill are in reduced electrical-energy consumption. Reductions in energy

consumption of between 179 and 358 kWh/ton

of pulp may be achieved by recycling, so Process heat requirements remain approximately

the same when recycling is used, but the

amount of recoverable waste heat is decreased

from 3.5 million to 2,2 million Btu.

Substantial technical improvements are possible in mechanical pulping processes within

the next 20 years, providing that economic incentives exist and capital formation is possible.

Chemical Pulping

Commercial Chemical Pulping Technologies

Chemical pulping processes involve treating

wood chips with chemicals to remove the lignin and hemicellulose, thus separating and

delignifying the fibers, Delignification gives the

fibers greater flexibility, resulting in a substantially stronger sheet of paper—because of greater contact between the fibers in the finished

sheet—than can be manufactured from fibers

with lignin produced by mechanical pulping.

Two major chemical pulping technologies

are currently in use: 1) kraft (sulfate) pulping

and 2) sulfite pulping. The kraft process dominates the pulp and paper industry, accounting for over 75 percent of all pulp produced

for paper and paperboard in 1979. 51 Other

chemical pulping processes, such as acid sulfite pulping, bisulfite pulping, and neutral sulfite semichemical pulping account for approximately 3 percent (the remainder was produced

by mechanical pulping), Paper made from pulp
86 ● Wood Use: U.S. Competitiveness and Technology

I

I

I

I

I

I

I

I Oil

I

I

Coal I

I

I

I

I

I

t 1

I

Paper (1 D ton) i

I

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Ch. Ill—Pulp, Paper, and Fiber Products ● 8 7

produced by the kraft process accounts for

most of the bleached boxboard and linerboard

used by the packaging industry (which consumes 58 percent of the paper in the United

States).

In addition, bleached softwood kraft pulps

often are mixed with mechanical pulps to add

strength to newsprint and printing papers.

Bleached hardwood kraft pulps are added to

bleached softwood pulp to improve printability

for specialty paper products like magazine

stock and coated papers.

KRAFT (SULFATE) PULPING

The kraft process involves treating wood

chips and sawdust with a sodium sulfide and

sodium hydroxide solution. The highly alkaline

chemical mixture is cooked in a digester for

1 to 3 hours at temperatures ranging from 320°

to 3500 F (fig. 25). The complete pulp and paper making process is shown in figure 26.

Fiber recovery from the kraft pulping process is largely a function of the wood species

used, the amount of chemicals used, the time

and temperature of cooking, the degree of

bleaching, and the paper strength required.

Generally, kraft pulp recoveries from softwoods are approximately 47 percent for unbleached pulp and 44 percent for bleached. s’

Hardwood recoveries range from 50 to 52 percent for unbleached kraft pulp and 45 to 50 percent for bleached.

Energy is used in a mill in different forms

(as chemical heat of reaction, as thermal energy, and as electrical energy), and these typically

are expressed in different units (Btu for thermal and for heat of reaction in fuel combustion, and kWh for electricity). While the units

may be converted simply (i.e., 1 kwh = 3,412

Btu), the actual forms of energy may not be converted without loss of energy available for doing useful work. Thus, in a typical powerplant,

it takes 10,000 Btu of heat input to produce 1

kWh of electricity (in contrast to the unit conversion above), and two-thirds of the input is

szp, J Hu~~ey, Comparison of Mills Energy Balance: Effects

of Conventional Hydropyrolysis and Dry Pyrolysis Recovery Systems (Appleton, Wis.: Institute of Paper Chemistry, 1978).

lost as exhaust. There are, then, two ways to

compare a mill’s energy uses: 1) simple unit

conversions, representing all uses in a common

unit; or 2) representing all uses in terms of the

heat values of their original forms, while recognizing energy conversion losses.

The different conclusions reached by these

approaches is illustrated by the following: the

first method gives rise to the conclusion that

self-generation in today’s typical kraft paper

mill provides about 50 percent of the mill’s energy needs, while the second method (table 28)

shows that 82 percent of the primary fuel supplying the total energy needs of a typical kraft

mill is self-generated. The first method relates

better to concerns for fossil-fuel avoidance,

while the second helps relate the fuel value of

wood-process residuals to other potential uses.

Of the two approaches, the latter is the more

useful for assessing process efficiency.

Energy consumption is a major cost in the

manufacture of kraft pulp and paper. The combined process requires approximately 30 million Btu of primary fuel per ton of bleached

kraft paper (table 29). This energy value includes fossil fuel burned at an outside powerplant to provide purchased electricity as well

as the thermal energy derived from the wood

resource. Approximately 78 percent of the energy demand is for thermal energy used in the

plant, the major portion of which is used for

paper making and self-generation of electricity

rather than in the pulping process. While the

combined kraft pulp and paper making process requires approximately 1,050 kWh/ton of

electricity, mostly for drive motors, all but 101

kWh generally is produced internally through

cogeneration (table 29). Burning waste liquors

and bark provides 82 percent of a mill’s primary energy needs.

The kraft process is suitable for pulping both

softwoods and hardwoods. Wood chips, sawdust, and wood residues from sawmills and veneer mills can be used as furnish, Over 35 percent of the total wood supplied for kraft paper

are wood residues. In the Pacific Northwest,

nearly 90 percent of the wood originates from

sawmill or veneer mill residues. Whole tree

chips, including bark and branches, currently
are used in limited quantities, although their

proportion of the total furnish is increasing. Because of the density, extractive content, and

chemical nature of these materials, increases

in their use may cause the pulping liquors

(chemicals) to react more slowly, resulting in

a need for longer digestion periods and increased energy expenditures.

SULFITE PULPING

The four fundamental sulfite pulping processes currently in commercial use are: 1) acid

sulfite, 2) bisulfite, 3) neutral sulfite, and 4) alkaline sulfite. The major differences between

the sulfite processes are the levels of acidity

and alkalinity of the sulfite chemical solutions

used to break down the wood and remove the

lignins. The cooking liquor consists of a salt

base—generally calcium, magnesium, sodium

or ammonium—and sulfuric acid. Sulfite processes are suitable only for species with low extractive contents, i.e., those low in tannins,

polyphenols, pigments, resins, fats, and the

like, because of the interference of these substances with the sulfur pulping process. Although calcium is the cheapest base available,

it forms insoluble compounds that cannot be

reclaimed economically or disposed of easily.

Thus, calcium-based pulping is seldom used.

Because magnesium- and sodium-based chemicals are recoverable, and ammonium-based

chemicals can be burned without harmful environmental effects, they are the most frequently

used.

Sodium-based sulfite pulping can consist of

multistage cooking, successive stages of which

differ in acidity. Because one stage optimizes

chemical liquor penetration and the other the
Ch. Ill—Pulp, Paper, and Fiber Products ● 8 9

Table 28.—Energy Demand Per Ton of Kraft Paper

Thermal:

Process:

Digester. ... .

Bleach plant .

Paper machine

Evaporation. .,

Liquid heating

Other . . . . . . . .

Subtotal ... . .

Lime kiln . .

Total . ... . .

Electric:

Self -generated:

Energy demands

Million Btu

. . . . . . . . . . . . . 3.8

. . . . . . . . . . . . . . 2.4

. . . . . . . . . . 6.8

. . . . . . . . . . . . . 3.0

. . . . 2.9

. . . . . . . . . . . . 2,5

. . . . . . . . . . . . 21,4

. . . . . . . . . . . . . . 2,0

. . . 23.4

. . . .

Fuel-value material recovered in

plant and burned for electricity 5.7b

Purchased from outside: ... ...

Fuel used by outside powerplant

to produce electricity . . . . . . . . 1 .0c

Totals:

Total electricity . ... . ...

Total fossil fuel consumed . . . . . . 30.1 —

aHurley, P J

kWh

949a

101 a

1,050

blncremental heat ra[e tO generate electricity In plant 6000 BtulkWh

cAssumes out SI de electrlc PI ant IS fess! l-fueled at 10,000 BtulkWh

SOURCES J J Watkins and W S Adams, “The St Regls Hydrolysis Process

as an Approach to Energy Conservation In the Pu 1P & Paper Industry, ”

Proceed~ngs of TAPP/ ’78 Engfr?eenrrg Corrference Book ///

P J Hurley, Corrrpar/son of Mi//s Energy Rdar?ce Effects of Conven

f/ona/ Hydropyro/ys/s and Dry Pyrolysls Recovery Sys(erns (Appleton,

WIS Institute of Paper Chemistry, 1978)

removal of lignin, more lignin may be removed

with less fiber degradation, so that fiber yields

are higher, fibers are stronger, and a wider

range of wood species may be used. Neutral

sulfite pulping, using sodium and ammonium

bases, recovers the largest proportion of fiber

(75 to 90 percent) of all the sulfite pulping

methods.

Improvements in Chemical Pulping

Two kinds of improvements have been made

in chemical pulping technologies: 1) better efficiency of current processes and 2) development

of new pulping technologies that depart from

the conventional commercial processes. The

greatest potential for dramatically improving

pulp and paper manufacturing lies in new technologies. Such innovations could enable the

use of large quantities of currently underutilized hardwood species and may even have

prospects for developing superior new papers

for future specialized uses. At the same time,

new concepts in energy use and cogeneration

could achieve new levels of energy efficiencies.

Among the most promising new pulping and

papermaking processes are: 1) press-dried paper, 2) green liquor pulping, 3] autocausticizing, and 4) pyrolytic recovery of chemicals in

spent pulping liquor. These developing technologies are not yet commercially available.

PROCESS IMPROVEMENTS

Major efforts in process improvements, or

means in which the efficiency of existing commercial processes is improved, have centered

on increasing fiber recovery and energy efficiency. Most such efforts have focused on the

kraft process, which produces 90 percent of all

chemical pulps manufactured. Greatest emphasis has been placed on reducing energy consumption because it is the largest cost factor.

Anthraquinone (AQ) recently has been tested

as a catalyst in kraft pulping. When added in

small quantities to the cooking liquor, AQ

speeds up the pulping process and can improve

fiber recovery by as much as 2 to 4 percent.

Although the percentage increase in yield may

seem small, the increases in absolute yield are

considered substantial because of the very

large volumes involved. AQ pulping was developed by Canadian Industries, Inc., and is

Table 29.—Energy Consequences of Pyrolytic Recovery (basis: 1 ton pulp)

Recovery method

Energy required Conventional hydropyrolysis Dry pyrolysis

Process yield (percent ovendried) . . . . . . . . . . . . 47.5 48.75 47.5

Electricity (kWh):

Internally generated . . . . . . . . . . . . . . . . . . . . . . . . . 949 850 812

Purchased . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 256 258

Inplant fossil fuel (thousand Btu) ... . . . . . . . . . . . . . . . 10,411 5,458 6,296

Inplant fossil-fuel savings (percent). . . . . . . . . . . . . . . . . . . . 48 0/0 40 ”/0

Paper Chemistry 1978)
90 ● Wood Use: U.S. Competitiveness and Technology

used commercially in both Japan and the

United States. Its potential broad-scale application in the United States, however, maybe limited by its cost and the lack of technology to

recover the used AQ.53 The U.S. Food and Drug

Administration (FDA) recently has approved

AQ for use in paper packing for food, opening new market potentials for AQ pulp.

The industry’s goal is for the kraft pulping

process to become as energy self-sufficient as

possible. Substantial gains in energy efficiency

are expected within the next 20 years, but it

is not known whether total self-sufficiency is

attainable. Kraft mills may approach self-sufficiency if some modifications are made; for

example: 1) the temperatures in boilers that

burn wood residues and black (lignin) liquor

can be reduced (primarily by adding more efficient heat exchangers for heat recovery, and

2) lime kilns maybe fueled with dried sawdust

without seriously contaminating the calcined

lime used for making the pulping liquor. The

latter has been demonstrated successfully in

Sweden. 54 These system modifications are expensive and may increase the operating costs

of a plant. Their adoption will depend on the

future costs of energy and the availability of

capital.

GREEN LIQUOR PULPING AND AUTOCAUSTICIZATION

Economy in chemical pulping depends on effective recovery of chemicals from the used

cooking liquor. Upon interaction with wood in

the cooking process, the “white liquor, ” that

is, the original sodium sulfide and sodium hydroxide solution, becomes “black liquor,” rich

in lignin salts and other organics removed from

the wood in the pulping process. The black liquor is pumped to evaporators that remove the

water and concentrate the remaining salts and

organic solids. The resulting viscous solution

is burned in a recovery furnace to remove the

organic residues (fig. 26).

The remaining salts—mostly sulfides and carbonates of soda—form a molten stream referred to as “smelt” and are recombined with

water to form “green liquor. ” The sodium carbonates in the green liquor normally are converted into hydroxides for reuse by the addition of calcium hydroxide in a process referred

to as “causticizing.”

Pulping of hardwoods and softwoods using

green liquor, which eliminates the causticizing process, is now an accepted commercial

technology for producing semichemical pulps.

In this process, disodium borate is used instead

of sodium hydroxide in the original white liquor, and the liquor produced by dissolving the

smelt can be reused directly in the digester. In

this way, the entire regeneration loop, including the lime kiln, is removed. As much as 18

percent of the fossil energy required for pulping can be eliminated by autocausticization.

Elimination of the lime kiln not only reduces

energy consumption, but reduces capital costs

by $35/annual ton of capacity and operating

costs by $3/ton. 55 Industry experts give autocausticizing a high probability of commercial

acceptance.

PYROLYTIC RECOVERY

Technology for pyrolytic recovery of black

liquor has been developed in two processes: 1)

a hydropyrolysis method developed by the St.

Regis Paper Co., and 2) a dry pyrolysis method

developed by Weyerhauser Corp. Pyrolytic recovery consists of applying heat in the absence

of oxygen (anaerobic combustion) to decompose the organic compounds in the black liquor. These new spent-liquor recovery techniques, designed to extract energy from the

spent liquor while retaining the chemicals for

reuse, are more energy efficient than are current processes. They are important because regeneration of the pulping chemicals requires

a large share of the energy used in the pulping

process.

Hydropyrolysis technology currently is being evaluated on a pilot basis in St, Regis’ Pensacola, Fla., mill. The process shows potential

53Hub~r, op. cit., P. 85.

WK. Lappe, “Advanced Drying Process is Key to Burning Peat,

Wood Byproducts, ” Energy Systems Guidebook (New York:

McGraw-Hill, 1980).

‘5]. Jansen, “Pulping Processes Based on Autocausticizable

Borate, ” The Delignification Methods of the Future (Helsinki,

Finland: Europa Symposium, 1980).
Ch. Ill—Pulp, Paper, and Fiber Products ● 9 1

for reducing the energy requirements for evaporating weak black liquor, i.e., that recovered

in the initial washing stage, and for aiding in

the energy recovery process. It is estimated that

fossil-fuel energy required for generation of

process heat may be reduced by 50 percent

with the application of hydropyrolysis technolog y. 56

St. Regis’ experience with its pilot plant indicates that application of hydropyrolysis technology results in a tradeoff between purchased

fossil fuel and purchased electricity. Lowered

heat requirements for liquor recovery result in

less process steam; thus, the potential for cogenerating electricity along with the steam

needed is limited. The results of these tradeoffs are shown in table 29, where the data suggest that an in-mill fossil fuel savings of up to

48 percent can be achieved with hydropyrolysis and approximately 40 percent with dry

pyrolysis. However, considering the fossil fuel

used to generate the purchased electricity, the

net fossil fuel savings are 28 percent and 20

percent, respectively.

OTHER CHEMICAL PULPING TECHNOLOGIES

Attempts to develop alternative pulping technologies that increase yields, energy efficiency,

and pulp quality of the kraft process have led

to two new chemical pulping concepts that

show some promise: 1) organosolv (alcoholysis)

pulping and 2) oxygen pulping. Since both still

are under development, and neither has

reached the demonstration stage, they must be

considered long-range (25 + years) prospects

for commercial application,

Organosolv Pulping.-Organosolv pulping is a

two-stage process involving hydrolysis (decomposition of the wood by dilute acids or enzymes) and the removal of lignin with an organic solvent, usually a mixture of alcohol and

water. The still-experimental process is suitable

for both hardwoods and softwoods. Pulp recovery from organosolv pulping ranges between

50 and 60 percent for hardwoods, and 40 and

45 percent for softwoods. Typical hardwoodfiber recoveries compare favorably with those

from kraft pulping: approximately 50 percent

for red alder, sweetgum, and American sycamore, and 60 percent for cottonwood and trembling aspen.

Fibers produced by the organosolv process

are weaker than those recovered by the kraft

process, Thus, the papers produced from

organosolv pulp are suitable for uses where

strength is not the most important property,

such as for printing papers, fluff pulps, and

dissolving pulp,

Reaction temperatures are low—between

320° and 370° F for hardwoods and 360° to

3900 F for softwoods if acid catalysts are used.

Little waste is produced by the process, and

low alcohols are recovered easily by distillation, thus requiring relatively low capital investment .57

Oxygen Pulping.—An extension of existing oxygen bleaching technologies, oxygen pulping

may reduce or eliminate the need for bleaching

plants in the paper mill. Oxygen pulping involves the introduction of gaseous oxygen into

the pulping liquor to stimulate oxidative fracture of the cellulose-lignin bonds. This process could save capital and operating costs

because equipment costs are lowered, less

bleaching chemicals are used, and pollution

control expense is cut by eliminating chlorine

from the bleaching process.

The cost of oxygen pulping is largely a function of the cost of oxygen. Oxygen production

requires approximately 400 lbs of oxygen and

54 kWh/ton of pulp produced (based on 1.2

kWh/hundred cubic feet(H3),or0.135 kWh/lb.

Several manufacturers currently are developing plant equipment capable of applying oxygen pulping commercially.

PRESS DRYING PAPER

Press drying technology developed at FPL

shows promise for both reducing the amount

of energy required in the paper-making process and enabling the use of underutilized hard57N Sa ~, b.er, .$ta tcls of N~t%F Pulping Processes; Problems (i tl[]

pe~s~ectjl,es (~fa~ison, Wis,: U.S. Forest Product I.aborat(}r},

1982], p. 10,
92 ● Wood Use: U.S. Competitiveness and Technology

wood species. Press drying uses high-yield

hardwood or softwood kraft pulp to produce

linerboard with strength superior to that of

conventional softwood kraft paper in every respect except tear strength (table 30). At the

same time, press drying can reduce the amount

of energy used in the drying process by applying pressure to the fiber (pulp) mat as it is dried.

With conventional drying technology, pressure

and heat are applied separately.

The superior strength of press-dried paper

comes from the combined effects of heat and

pressure, which force the fibers into closer contact and cause stronger bonds to be formed between them. The heat and pressure also cause

natural polymer flow and cross-linkages among

the fibers as a result of the hemicellulose contained in the pulp. Paper produced from pressdrying kraft red oak pulp has been shown to

have burst strength and tensile strength approximately 13 percent higher, and compression strength 50 percent better, than that of

conventionally dried pine kraft paper. The

lower tear strength of press-dried hardwood

paper may limit its use for wrapping or sack

paper; however, its higher burst strength and

tensile strength make it suitable for linerboard.

Estimates of the potential net energy savings

from using press-drying technology are about

19 percent for the papermaking process, 58 Although a commercial-scale, press-dried papermaking machine has not been built yet, press

drying may actually reduce equipment requirements and capital investment in both the drying section and the pulping process because

it can use unrefined pulp.59 The major limitation to press drying paper, which must be overcome before the technology can be applied

commercially, is the low speed of the papermaking machine and the resulting slow production rate of the pilot-scale equipment used

at the FPL.

Dissolving Pulp Technologies

Dissolving pulp technologies are not pulping

technologies as such, but secondary processes

that produce nearly pure cellulose (alpha-cellulose) for conversion to rayon, plastics, and

other chemicals. Pulps made by either the kraft

or sulfite process are purified further chemically to remove all hemicellulose and leave only

pure cellulose, which then can be transformed

into products like viscose rayon, cellophane,

and acetate fibers and film. The largest single

use for dissolving pulp is in the viscose rayon

process, which accounts for over 99 percent

of the world’s rayon production.

A variety of hardwood and softwood species

is suitable for the production of dissolving

pulp, including pine, hemlock, spruce, oak,

birch, and gum. Highly resinous wood, such

as Southern yellow pine, normally is not used

for dissolving pulp because of the difficulty of

removing extractives in the purification process. The highest grades of dissolving pulp are

called cord, acetate, and nitrate pulps, which

approach 98 percent pure cellulose; normal

grades of viscose rayon pulp contain some

hemicellulose and maybe only 93 percent pure.

Because of the need for nearly pure cellulose,

“v. Setterholm and Peter Ince, “The Press Drying Concept

for Papermaking, ” Southern Lumberman, Dec. 15, 1980.

59P. J. Ince, “FPL Press Drying Process: Wood Savings in Linerboard Manufacture,” TAPPI, vol. 64, 1981, p, 109,

Table 30.—Strength Properties of Press-Dried

Hardwood Paper and Conventional Softwood Paper

Anticipated Present Conventional

strength strength strength

with oak with oak with pine

Burst strength (lb/in w)a . . . . . . . . . . . . . . . . 155 145 97

Tensile strength (lb/in w) . . . . . . . . . . . . . . . 100 68 54

Compression (lb/in w) . . . . . . . . . . . . . . . . . . 45 30 20

aPounds per inch of width

SOURCE U S. Forest Products Laboratory, 1981
Ch. lIl—Pulp, Paper, and Fiber Products ● 9 3

pulping yields for the kraft and sulfite processes are reduced to approximately 28 to 38

percent, depending on the pulp purity desired.

The low yield of high-quality, alpha-cellulose

pulps makes them expensive to produce—energy and pulpwood costs account for 50 to 60

percent of the manufacturing costs.60

Total U.S. production of dissolving wood

pulp was approximately 1.5 million short tons

in 1979 (23 percent of world production). Approximately 61 percent of the dissolving pulp

produced was used for textile fibers; the remainder was used for the manufacture (in descending order) of chemicals and plastics, cellophane, cellulose nitrate (for propellants), and

specialty papers for use in industrial and automotive filters.

In addition to the viscose rayon process for

the production of fibers and cellophane (which

is made by the same viscose process but is extruded through a slot to form film rather than

through holes to form threads), cellulose may

be converted into acetate forms (acetyl esters)

that can be manufactured into cellulose acetate, cellulose diacetate, and cellulose triacetate

for conversion into fibers. Cellulose nitrate

continues to be produced in significant quantities as an explosive and a propellant. Other

products manufactured from dissolving pulp

include ice cream thickeners, detergents, carbon fibers of high strength and stiffness, and

gels used in hand lotions and food products.

Rayon Manufacture

Rayon, first made in 1881, is the oldest manmade synthetic fiber. The success of rayon in

the

●

●

market is due to several factors:

Cellulose continues to be the cheapest

polymer for fabrics.

Rayon’s moisture absorption, capacity for

absorbing dyes, and ability to swell makes

it suitable for clothing. Rayon also can be

blended with other synthetic fibers, like

nylon, to improve their moisture-absorbing

qualities.

OOC, B. Metz, “Dissolving Pulps-The Future Economic Situation, ” Proceedings of the 5th International Dis.~ol~in,g Pulp.s

Conference (~’ienna, Austria: Oct. 8-10, 1980).

● properties of the dissolving pulp can be

varied to produce pulps suited for specific

end uses. For example, ITT Rayonier, a

leading U.S. producer of dissolving pulps,

offers 16 grades of pulp matched to the

properties of the rayon to be produced.

Rayon is made by dissolving cellulose xanthate in alkali and spinning the fiber through

small pinhole jets into a sulfuric acid bath,

which coagulates the fiber into final form. If

the same xanthate-viscose solution is forced

through a narrow slit, a cellophane film is

formed.

Major developments in rayon technology

have been aimed at:

improving the efficiency of rayon production;

reducing energy requirements;

controlling or eliminating environmental

pollutants generated by the viscose rayon

process;

developing more cottonlike rayons to supplement cotton production; and

developing a completely new system for

converting chemical cellulose to fiber

by a nonviscose, environmentally sound,

more efficient process using recoverable

cellulose solvents. 6l

Major emphasis has been placed on developing a rayon with a high wet-strength to remedy the shortcomings of conventional rayon

and to compete with cotton more effectively.

A number of new fibers outperform conventional rayon; they include Courtauld’s “Corval, ” a cross-linked fiber; American Viscose’s

“Avril”; and Enka’s “Fiber 700. ”

Process developments within the rayon industry seem to be moving toward automation

and computer control. Experts foresee new,

versatile rayons made by solvent-extrusion

processes similar to those used for making nylon and polyester. These may lead to a future

one-step process from pulp to viscose solution;

however, many of the current developments i n

this area are treated as proprietary and are no t

open to inspection .

“G, Daul, “Rayon Revisited, ” Chemtech, Februarj 1981, p. 84.
94 ● Wood Use: U.S. Competitiveness and Technology

The viscose process is one of the most versatile for manufacturing textile fibers. Modification of the viscose manufacturing process

easily can accommodate stretching and orienting the fiber and building certain desired properties into it. For example, it is known that the

addition of metallic salts, such as zinc and

other modifiers, will delay the reformation to

rayon to allow time for spinning and manipulating the fiber. Formaldehyde also has been

found to be an effective modifier for the production of super-strong fibers; however, environmental problems associated with it must

still be overcome. 62

Research to improve the strength and performance of rayon materials continues. These

efforts include the search for new solvents for

use in the spinning (forming) process. One such

process that shows promise uses a special solvent (methyl-morpholine-N-oxide, MMNO) to

orient the molecules in solution to form rayon

with high-strength cellulose fibers. Success of

the MMNO process may depend on development of a solvent recovery system needed to

make the manufacturing process economically

competitive. 63 Some experts see the testing of

other new solvents leading to a major new system for manufacturing rayon. 64

Other Cellulosic Products

A number of other

from dissolving pulp.

‘Z1bid., l]. M.

products can be made

For example, cellulose

L33R, N. Armstrong, C. C. McCorsky, and J. K. Varoa, ‘‘Spinnable Solutions of Cellulose Dissolved in Amine Oxides, ” f%octxxiings of the 5th International llissol~’ing PUII>S Conference

[Vienna, Austria: oct. 8-10, 1980).

~411, I,. Hergert, R. B. Hammer, and A. F. Turbak, ‘‘New Methods for Preparing Rayon, ’ Proceedings of the 4th International

Dissol~ing Pulps Conference (Chicago, 111.: Sept. 28-30, 1977),

acetate is produced by steeping dissolving pulp

or cotton liners in acetic acid to prepare fibers

for conversion to acetate, This same process

may be used to produce cellulose butyrate and

cellulose propionate for the production of

plastics.

An acetate of slightly different chemical

form, cellulose triacetate, also can be made

from dissolving pulp. Unlike rayon, it is waterrepellent like nylon, orlon, and terylene. Its

water repellency is attributable to the degree

of acetylation of the fibers. It has good thermal properties and wear characteristics, and

frequently is used in fabric blends with nylon,

wool, and rayon in women’s clothing.

Cellulose esters—acetate ester, acetate butyrate, and acetate propionate—are a family of

plastic materials derived from dissolving pulp

that can be formed, molded, and extruded by

a variety of thermoplastic processes. Higher

forms of these materials also maybe prepared;

however, their high production costs restrict

them to highly specialized applications such

as cellulose acetate phthalate, which is used as

a coating on pharmaceuticals. Cellulose ester

powders are used in fluidized-bed and electrostatic coating processes, as well as in rotational

molding processes. Modified cellulosic polymers are used in preparation of films, coatings,

fibers, lacquers, and adhesives,

Finally, dissolving pulps also may be used to

produce a variety of chemical products, including methyl- and carboxymethyl-cellulose, that

are used as thickeners in latex paints and ice

cream; ethylcellulose, used as a thermoplastic

molding compound; and nitrocellulose, used

as a propellant/explosive.