Papers and Abstracts page

Products from Recycled Fibers - A U.S. 

Perspective 

Thomas E. Hamilton, Joanne T. Alig and Robert H. Falk 

Abstract 

The issue of sustainability underlies most concerns surrounding forests and their use in the 21st century. 

Recycling offers a rational way to conserve forest resources, reduce demands on other natural resources 

and ecosystems, and still meet human needs for wood-based materials. However, markets for recovered 

raw materials constitute a major barrier to successful recycling. The USDA Forest Service, Forest 

Products Laboratory, is researching and developing new technologies that efficiently turn recovered 

wood and paper fiber into higher value products. Such research includes assessing the available 

recovered fiber supply, developing technologies to produce wood-based products suitable for housing 

and other industrial applications, developing technologies to improve the utilization of recovered paper 

fibers, conducting economic analyses, and ensuring that products made from recycled fiber meet 

accepted performance standards. From a U.S. perspective, creating and implementing these new 

technologies is best accomplished through effective partnerships between government, academia, and 

industry. 

Keywords: Recycling, waste, recovery, reuse. 

Introduction 

Forests contribute in many ways to our well being: Forests play a crucial role in watersheds by 

providing slope stability; aid in climate regulation; furnish habitat for wildlife; provide human leisure 

and recreation; render nontimber resources such as floral greens and edible mushrooms; and supply 

timber resources for producing fuel, making furniture, constructing homes, building bridges, and making 

paper. In short, the demands on our forests are numerous, and we need to ensure that we are using them 

wisely and in a sustainable manner. 

When the concept of sustainable development was presented in the 1987 United Nations report, "Our 

Common Future," it clearly contained the message that the environment and economics cannot be 

treated separately and that material needs must be met in ways that preserve the biosphere. In 1992, a 

report of the National Commission on the Environment, "Choosing a Sustainable Future" (World 

Wildlife Fund 1992), endorsed the 1987 United Nations report and went one step further. The 

Commission stated that "long-term growth depends on a sound environment, and resources to protect the 

environment will come from economic strength." The point here is important - it is a circular 

relationship: a strong economy depends on a healthy environment and a healthy environment depends 

on a strong economy. 

The U.S. forest products industry contributes positively to the U.S. economy. In nearly every U.S. state, 

the forest products industry is one of the top ten manufacturing employers. In total, nearly 1.4 x 106 

people are employed in lumber and wood products and the paper and allied products industries in the 

United States (U.S. Bureau of Census 1994). Together, these industries produce nearly US$200 x 109 in 

shipments every year, making up more than 7% of all manufacturing in the United States (U.S. 

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Department of Commerce 1993). 

Our dependency on forest products is growing. Nearly half (by weight) of all industrial raw materials 

used in the United States (steel, concrete, plastics) is wood based. Residential construction is the 

dominant market for most timber products in the United States, and a 13% increase in lumber 

consumption per housing unit is projected in the next 45 years. In total, lumber consumption is projected 

to grow approximately 30%, to 74.0 x 109 board feet 

(260 x 106 m3) in 2040. Consumption of structural panels (softwood plywood, oriented strandboard, 

and waferboard) is expected to reach 42.3 x 109 ft2 (3.9 x 109 m2) by 2040, an increase of 70% above 

1990 consumption levels. Consumption of nonstructural panels (hardwood plywood, insulating board, 

hardboard, and particle board) is also projected to increase to 28.4 x 109 ft2 (2.6 x 109 m2) by 2040, an 

increase of 28% above 1990 levels. Finally, pulpwood consumption is expected to grow more than 53% 

in the next 45 years. In total, U.S. timber consumption in terms of roundwood volume is expected to 

reach 26.5 x 109 ft3 (750 x 106 m3) in 2040, more than 40% above 1990 consumption levels (Haynes et 

al. 1995). 

In the past, growing demand for products translated into greater emphasis on timber harvesting. 

Although we acknowledge that great strides in conserving resources can be made by reducing our 

material use, we must be realistic in recognizing that the demand for products will not diminish. 

Population in the United States is expected to increase from 262 to 338 x 106 by 2025; world population 

is expected to increase from 5.6 to 8.9 x 109 by 2025. On a worldwide basis, this means that we face the 

need to find new ways to conserve our forest resources. In addition, in the United States we are facing 

increasing restrictions on harvesting of forest lands. This raises the question of how to meet growing 

demand for wood-based products while still meeting our sustainability goals. Recycling of wood fibers 

provides an opportunity to meet both objectives to provide the raw material used in making wood-based 

products and to conserve forest resources. Assuming recycled paper products can be substituted for 

virgin wood material when producing paper and paperboard, it has been estimated that accelerated 

recycling has the potential 

to offset the need to harvest 400 x 106 ft3 (11.3 x 106 m3) of sawtimber and pulpwood (Haynes et al. 

1995). 

U.S. Recycling 

Most industrialized nations have been actively pursuing new technologies to recover more materials 

from postconsumer and postindustrial waste streams. In the United States, this effort gained momentum 

in the late 1980s when the growing volumes of material disposed in landfills resulted in public pressure 

to reduce the availability of land for new dump sites. In 1993, 44% of the municipal solid waste 

generated in the United States consisted of paper, paperboard, and wood products (U.S. EPA 1994). 

Because of this large percentage of municipal solid waste, U.S. state and local laws and regulations were 

passed that required recovery and reuse of many wood-based products. 

Currently, every U.S. state regulates recycling or solid waste management. State governments encourage 

reuse of recovered material through demand-side mandates such as minimum content standards, tax 

incentives, green labeling, and procurement standards. State legislators have also pursued mandates to 

increase the supply of recovered materials. They have prohibited products from being disposed in 

landfills and adopted recycling goals that specify a percentage of the waste stream to be recovered for 

recycling, reduced at the source, composted, or otherwise diverted from landfills. 

The U.S. pulp and paper industry has also adopted recovery goals to increase the amount of paper 

material recovered from the municipal solid waste stream. In 1990, the U.S. paper industry proposed a 

40% recovery goal by 1995. That goal was met in 1994 when 38.6 x 106 tons of paper were recovered 

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in the United States - just over 40% of all paper used. The U.S. paper industry has since set a new goal 

to recover for recycling and reuse half of all paper used by the year 2000. 

In addition to conserving our resources, re-cycling offers many societal benefits. Recovery of materials 

can extend the life of existing landfills and offset the need to find new landfills. Cities throughout the 

United States are finding that recycling offers employment and, when successful, brings in revenues to 

help lower the cost of refuse collection. Further, processing recovered paper fiber requires less energy 

than processing virgin materials, thus generating less carbon emissions (Skog 1995) and helping the 

U.S. government meet its objective of keeping net emissions of carbon to levels no greater than those in 

1990. 

The USDA Forest Service, Forest Products Laboratory (FPL), recognizes the benefits of recycling and is 

researching and developing new technologies that efficiently turn recovered wood and paper fiber into 

higher value products. Such research includes assessing the available recovered fiber supply, developing 

technologies to produce wood-based products suitable for housing and other industrial applications, 

developing technologies to improve the utilization of recovered paper fibers, conducting economic 

analyses, and ensuring that products made from recycled fiber meet accepted performance standards. 

Waste Resource Supply Information 

Success in developing technologies to produce value-added products from recycled wood waste is 

dependent upon many factors, including the availability of a consistent and relatively uniform raw 

material source. Detailed raw material resource information is a necessary first step in developing any 

new technology or system to convert a raw material into a usable product. Adequate short- and longterm raw material supplies must be available at reasonable costs for a technology to be commercially 

adopted and implemented. Factors affecting the economic supply of recyclable raw materials include 

amounts and types of material generated, condition and quality of the material, extent of commingling of

materials, separability of materials, types of contaminants present, physical location of the material, and 

costs of acquisition, concentration, and transportation. Likely changes in these factors must be evaluated 

to determine possible effects on raw material supply. 

The capability to economically assemble a continuous supply of raw material requires innovations in 

collection, sorting, and distribution of waste materials. Directing materials to the highest value use is 

essential. In addition, a manufacturing firm must have some assurance of long-term supply, which 

includes both a continuous flow of suitable raw materials and the ability to compete economically in the 

raw material market place. 

Recycled Wood-Based Composite Products 

There are many opportunities to develop the technology needed to make composite products from 

recycled wood-based fiber. The fiber can be used alone to make low cost/high performance composites. 

Alternatively, recycled fiber can be combined with other recycled materials, such as plastics, to produce 

mixtures, compatibilized blends, and alloys. Finally, wood-based fiber can be combined with inorganic 

materials. Researchers at FPL lead the formation of a task force composed of government, industry and 

academia to provide a framework for research to develop composite products using recycled fiber 

(Rowell et al. 1993). 

Several essential issues need to be addressed to fully utilize post-consumer wood and paper wastes in 

composite products. First, characterization of the recyclable materials and their levels of contamination 

are needed. Secondly, the raw material needs to be converted into a form suitable for the manufacturing 

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process. Also, any effect of existing residual contamination on the manufacturing process needs to be 

quantified. Most importantly, the link between raw material characteristics and final product 

performance must be established. Finally, evaluation, testing, and design standards must be developed to 

use these products. 

In this paper, we discuss several existing and developing technologies that have the potential to produce 

recycled wood-based products suitable for use in housing and other industrial applications. One benefit 

of these technologies is that they provide an outlet for recycling other materials, such as some grades of 

plastic, or using agricultural fibers for which there is currently no economic use. 

Dry-Formed Wood Composites 

Dry-formed wood composites can be made from recovered wood fiber in much the same way as 

conventionally produced particle-based composites (e.g., particleboard, hardboard, medium-density 

fiberboard). Dry-formed processing involves breaking wood waste into strands, flakes, particles, or 

fibers and reassembling them into new forms with the aid of an adhesive. An important part of particlebased composite panel manufacture from virgin wood is a consistent and homogeneous raw material 

source to ensure uniform panel properties. Because the raw materials being considered here are derived 

from waste, the many forms and sources of wood waste will likely pose special processing 

considerations. For example, waste wood from demolition sites may be contaminated with lead-based 

paint, nails, stones, plastic, gypsum, and concrete. In addition to this surface contamination, the wood 

waste may contain preservative or fire-retardant chemicals. Research and development to efficiently 

process these raw materials will result in new, value-added products. 

Wet-Formed Structural Fiber Products 

Wet-formed structural fiber products can be produced from basic papermaking technologies (pulp 

slurry). Using a three-dimensional pulp-molding process, researchers at the FPL have produced a 

structural component called Spaceboard. It is anticipated that the Spaceboard technology will be used to 

produce a variety of housing components. This process can readily accept recycled wood fibers, and 

although now limited to rectangular panels, has the potential for both curvilinear and three-dimensional 

solid-formed products. This molding potential could greatly enhance design flexibility for architects and 

engineers. 

The FPL is also considering two potential technologies to utilize recycled wood fiber using wet-formed 

processes. One technology is a pulp extrusion process that has the potential to produce products with 

various dimensions and cross sections. Potential products developed with this process might include 

decorative molding and trim products and lumber substitute products. 

Another technology is a wet-formed fiber-based process that involves shaping structural components 

through the winding of paper sheet stock. This laminating process incorporates existing paper sheetforming technology and is familiar to most builders that have used paper tubes for concrete formwork. 

This type of process has the potential to utilize low-grade recycled paper stock. Because circular, 

rectangular, and other efficient cross-sectional shapes can be formed, a number of potential housing 

components can be produced with this laminating process. 

Wood-Plastic Composites 

Wood-plastic composites include those made by binding recycled wood fibers with recycled plastics, 

synthetic fibers, and resins. These combinations can produce a variety of composite building products. 

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Recycled wood-based fiber and plastics can be combined to make a wide spectrum of products, ranging 

from very inexpensive, low-performance composites to expensive, high-performance materials. Fiber 

technology, bonding performance, and fiber modification can be used to manufacture wood-plastic 

composites that have uniform density, durability in adverse environments, and a high level of strength. 

The primary application for fiber-thermoplastic composites is in extrusion molding. The natural fiber 

improves the rigidity and strength of the plastic and lowers the cost of the final products. 

Utilizing thermoplastics in composites has been limited to nonstructural uses by creep, which results 

from thermal or long-term loading deformation. However, thermoplastics (which melt when heated) can 

be converted to thermosetting materials (which are cross-linked and unable to melt), so that it would be 

possible to make creep-resistive structural products using recycled thermoplastics. Research and 

development to overcome such limitations can greatly increase the use of wood-plastic composites. 

Wood-Inorganic Composites 

Another recycling opportunity is to bond recovered wood and other postconsumer materials with 

inorganic materials. Recycled particles or fibers of wood held together with an inorganic binder, such as 

Portland cement and gypsum, form a composite that can be used in a variety of structural and 

architectural applications, such as lightweight concrete. Virgin-based wood and cement composites have 

found wide use in Europe, although their use is scarce in North America. 

Compared with conventional wood-building materials, wood-inorganic composites offer unique 

advantages in that these composites combine the advantageous characteristics of both the wood fiber and 

mineral matrix. These composites have good fire, noise, decay fungi, and insect resistance. 

The use of inorganic materials to bind recovered wood fiber, chips, and particles has proven to be 

technically feasible in commercial products such as sound insulation board, gypsum, fiberboard, and 

low-density cement-bonded wood building blocks. This range of products can be extended if means are 

developed to convert waste wood into optimal particle sizes. 

Recycled Solid-Wood Products 

One source of lumber that has great potential for reutilization is the "old" lumber and timbers from 

dismantled structures. In addition to the millions of single-family residential buildings in the United 

States, thousands of World War II military buildings that contain millions of board feet of usable lumber 

and timbers are slated for demolition. This demolition material is an attractive recyclable because it 

takes little energy to put it in reusable form. 

The lumber and timbers salvaged from the demolition of existing wood structures are becoming a 

building material with increased value. This is because large-sized virgin timbers are not readily 

available from contemporary forests. Also, salvaged timbers, while sometimes containing bolt holes and 

other defects, are usually well seasoned. 

The potential for utilizing old lumber or timbers depends not only on the economic feasibility of 

recovery compared with disposal, but the acceptance of used products in new construction. Because the 

grade of lumber is correlated to its structural performance and building officials require some measure 

of assured performance (typically given by the grade stamp on virgin lumber), a system is needed to 

grade old lumber. 

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Recovered Paper Technologies 

The use of recovered paper fiber to make new paper products has increased steadily over the past several 

years. However, there are several technical barriers to recovery and reuse of high grade paper materials. 

Research is needed to improve the ability to remove toners and other contaminants from recovered 

paper, improve fiber strength, and improve the bleaching process of recovered fiber. Furthermore, 

making paper with recycled fiber generates more sludge than making paper from virgin fiber. Research 

is needed to examine new uses for this sludge and develop new technologies that produce fewer 

byproducts. 

Improving Toner and Contaminant Removal 

Few paper products found in municipal solid waste contain only fiber. Recovered paper can contain 

toners, adhesives, fillers, dyes, metal foils, plastics, and dirt. Use of fibers from recovered paper to 

produce new paper products requires separating fibers from contaminants and cleaning. Success in 

developing technologies to improve toner and contaminant removal can greatly increase the raw 

material potential of municipal solid waste. 

One problem is that photocopiers and laser printers use nylon or plastic-based toners that, under high 

heat, bond to xerographic and photocopier paper. Recycling xerographic and photocopier paper into 

printing and writing paper is difficult and costly. FPL is examining the use of commercially available 

biodegradable enzymes to enhance conventional removal processes. This enzymatic deinking process 

uses a low amount of chemicals, resulting in a cleaner process water with effluent that is lower in 

oxygen demand and less toxic. Further, enzymes are readily biodegraded and do not cause problems in 

environmental cleanup. This technology separates toner from fibers more effectively, improves pulp 

brightness and drainage, thus allowing for greater production. 

Increasing Fiber Strength 

Recycled fiber is weaker than virgin fiber as a result of the changes that occur during the drying phase 

when the fiber is first made into paper. The drying dehydrates the fibers under high temperatures and 

pressure. This hardens the fiber surfaces and shrinks the pores that allow water to pass back and forth 

between fibers. These changes reduce the flexibility and the ability of the fibers to bond to one another, 

leaving short, stiff fibers that produce weak paper. 

Three technologies have the ability to improve the strength of recovered fiber. One technology involves 

soaking recovered paper fibers in various chemical treatments before disintegration. This technology 

restores the bonding potential of the dried fibers. 

A second technology involves using screens to separate the shorter and stiffer recovered paper fibers 

from those that are longer and more flexible. This technology allows for the use of the longer more 

flexible fibers to enhance paper strength, without creating a toxic effluent. A third technology allows an 

inexpensive inorganic filler to be substituted for some fiber in paper pulps so that the resulting paper is 

stronger and less costly to produce. This process, called fiberloading, creates a reaction that 

causes the filler to form within the fiber walls where it will not interfere with the bonding ability of the 

fiber. Technologies to increase fiber strength of recovered paper will ensure that recycled paper is 

comparable with paper made from virgin materials. This will enhance consumer acceptance and use of 

recycled paper products. 

Bleaching Recovered Fibers 

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One primary concern in using recovered fiber to make new paper products has been the brightness of the 

end product. In the past, the most commonly used aid for repulping and bleaching recovered paper was 

sodium hypochlorite. However, increased environmental concerns regarding the use of chlorine 

compounds in paper mills have resulted in the need to find alternative repulping aides (Kapadia 1992). 

The FPL research is examining other compounds (such as peroxymonosulfuric acid and its salts) that 

show promise as bleaching agents for recovered paper fiber. Some of these compare in effectiveness to 

using chlorine, but do not produce the same byproducts. 

Research is also underway to test the potential for using enzymes to remove lignin and bleach the pulp. 

If successful, this technology may be used in converting old corrugated containers (or fiberboard), which 

have a high recovery rate, into higher valued printing and writing papers. 

Decreasing Sludge 

Making paper from recovered fiber generates more sludge than making paper from virgin fiber. Sludge, 

a byproduct of pulp and papermaking, is a heterogeneous mixture of water, short or damaged wood 

cellulose fibers, and other contaminants. In a recent study by Scott et al. (1995), the energy and environmental costs associated with several disposal processes were analyzed. The study considered alternative 

incineration technologies, including applying the sludge to forest or agricultural lands. Results from this 

study provide valuable information about options for disposing of sludge from papermaking. 

In addition to finding new uses for sludge, new technologies can result in a decrease in the amount of 

sludge generated. One technology uses ultrafiltration screens to recapture fiber that escapes from the 

pulp as water is used to wash ink from the pulp. This technology improves the recovery of fiber and 

reduces the waste. In addition, the fiberloading technology discussed previously not only improves 

paper strength, but reduces the amount of sludge and emissions generated over conventional methods. 

Economic Analysis 

Economic analysis of current and future trends in recycling technology and markets provides important 

information for researchers and policymakers. Forest Service economists are studying long-term 

recycling trends and their broad economic, environmental, and energy impacts. The FPL researchers 

have collaborated with academic and industry partners to develop an economic model called the North 

American Pulp and Paper Model (NAPAP Model). This model provides long-range economic 

assessments of the North American pulp and paper sector. It has been used to examine the effects of 

recycling on pulp and paper markets by simulating technology for using recovered fiber and virgin wood 

fiber and makes projections of timber supply and demand, growth, inventory, and prices. A similar 

model for the solid wood sectors of the U.S. and Canadian economies is under development. 

Performance Evaluations and Standards 

Although there is great opportunity to utilize recycled wood-based materials using the described 

processing technologies, the products produced from them must perform satisfactorily. For building and 

paper products, performance standards ensure a product's acceptability. 

Each of the 6,000 grades of paper and paperboard products has established performance and quality 

standards that determine acceptability in the marketplace. These U.S. standards are set by manufacturing 

associations for each paper grade. A systematic analysis is needed to prioritize and target those grades of

paper that are best suited to accept recycled fibers. This will mean assessing the effect of recycled 

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content on paper performance in products made from recycled fibers. 

Recycled products used in housing and other industrial applications must also meet performance 

standards. Standards for building products result in an assurance of public safety as well as the 

facilitation of regulatory acceptance of 

the developed products and building systems. Therefore, evaluations of structural performance, fire 

performance, environmental performance (including moisture effects and durability), insulative and 

acoustical properties, and toxicity hazards are needed. The establishment of testing, design, and 

evaluation standards to measure and maintain this performance is 

also required. 

Standards organizations, such as the American Society for Testing and Material (ASTM), the American 

National Standards Institute (ANSI), and the International Standards Organization (ISO), develop test 

standards and performance criteria for comparing properties across a range of products intended for a 

specific application. The development of such "consensus" standards is the keystone to equitable 

treatment of properties across product lines and provides the consumer confidence in product 

performance and safety. 

Partnerships -Making Recycling a Reality 

Cooperative partnerships are essential for the timely implementation of new technologies. The FPL has 

already experienced many successes in creating partnerships for recycling technologies. Partners include 

individual companies, universities, and government agencies such as the U.S. Army and the U.S. 

Department of Energy. In addition, government research labs, such as the FPL, often work with state 

and local government agencies whose primary goal is to achieve increased recycling. State and local 

governments implement programs to ensure a steady supply of recovered materials. Researchers provide 

technical expertise to industry and can help facilitate the development of new technologies to utilize 

these recovered materials. Industry can then use these new technologies to process recovered materials 

into high value products with performance standards that ensure acceptability and use in the 

marketplace. By working together to recover, reprocess, and reuse re-cyclable materials, we can make 

great strides in ensuring the success of recycling efforts and conserving our resources for future 

generations. 

Concluding Remarks 

In the United States, we are making rapid strides in recycling wood fibers. In fact, we are ahead of 

schedule if we look at past goals and the timetables to reach them. However, much remains to be done. 

We have outlined the following six areas where technology is needed to make expanded recycling a 

reality: 

z Available supply assessment 

z Composites from wood and paper 

z Solid wood product reuse 

z Paper-to-paper technology 

z Economics research 

z Performance evaluations and standards development 

We believe that science is the key to expanding recycling. We also believe that a close 

science/manufacturing partnership is needed to make further recycling a reality: science to provide the 

technology and industry to implement it. If successful, the public will benefit through a broader array of 

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products and conservation of forest resources. 

References 

Haynes, R.W., Adams, D.M., and Mills, J.R., 1995: The 1993 RPA timber assessment update. RMGTR-259. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range 

Experiment Station, Fort Collins, Colorado. 

Kapadia, Pankaj C., 1992: A non-chlorine repulping aide. In: Proceedings of the 1992 Papermakers 

Conference. Atlanta, GA: TAPPI Press. 

Rowell, R.M., Spelter, H., Arola, R.A. et al., 1993: Opportunities for composites from recycled 

wastewood-based resources: a problem analysis and research plan. Forest Products Journal 43(1): 55-63. 

Scott, G.M., Smith, A., and Abubakr, Said, 1995: Landfill alternatives in the pulp and paper industry. 

Prepared for the Proceedings of the 1995 TAPPI Recycling Symposium; New Orleans, LA. Atlanta, 

GA: TAPPI Press. 

Skog, Kenneth, 1995: Personal communication. May. 

United Nations, 1987: Our Common Future. United Nations World Commission on Environment and 

Development, New York: Oxford University Press. 

U.S. Bureau of Census, 1994: Statistical abstract of the United States 1994 (114th edition). U.S. Bureau 

of Census, Washington DC. 

U.S. Department of Commerce, 1993: 1991 Annual survey of manufactures. Industry series. 1987 

economic censuses compact disk. Volume I. Release 1E. United States Department of Commerce, 

Bureau of the Census, Data User Services Division, Washington DC. 

U.S. EPA, 1994: Characterization of municipal solid waste in the United States: 1994 update. U.S. 

Environmental Protection Agency, Municipal and Industrial Solid Waste Division, Office of Solid 

Waste. EPA530-R-94-042. 

World Wildlife Fund, 1992: Choosing a sustainable future, the report of the National Commission on the 

Environment. Washington DC. 

OE Nov 21, 1996

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