PAPERMAKING 
 

FACTORS 
 

THAT INFLUENCE 
 

THE STRENGTH 
 

OF LINERBOARD 
 

WEIGHT 
 

HANDSHEETS 
 

RESEARCH 
 U.S. DEPARTMENT OF AGRICULTURE 
 

PAPER 
 FOREST SERVICE 
 

FPL 323 
 FOREST PRODUCTS LABORATORY 
 

MADISON. WIS. 
 

1979 
ABSTRACT 
 


This study explores the effects of 

typical papermaking factors on a number of 

strength properties of linerboard weight 

handsheets. Several papermaking factors– 

wood species, pulp yield, type of refiner, consistency of pulp during refining, amount of 

refining, wet-press pressure, and surface– 

were evaluated for their effect on the 

strength properties of 42-pound-per-thousand-square-foot handsheets. Wet-press 

pressure, wood species, degree of refining, 

and yield were found to be the most important. The degree and direction of change depend on the particular property. For example, 

increasing wet-press pressure significantly 

increased the compressive strength of the 

handsheets whereas the type of wood species had little effect. On the other hand, 

wood species had a significant effect on the 

tensile strain to failure while wet-press 

pressure did not. Considering all the properties in terms of end-use requirements, the 

handsheets made from low-yield southern 

pine pulp, refined at 3 percent consistency in 

a disk mill to 450 milliliters Canadian Standard freeness and formed using high wetpress pressure, gave the best overall results. 

CSF 

g

g/cc 

ksi 

Ib 

Ib/in. 

Ib/in.2 

Ib/in. w 

lb/M ft2 

mil 

ml 

MOE 

pct 

pt 

Abbreviations Used 

= Canadian Standard freeness 
 

= grams
 

= grams per cubic centimeter 
 

= thousand pounds per square inch 
 

= pounds 
 

= pounds per inch 
 

= pounds per square inch 
 

= pounds per inch of width 
 

= pounds per thousand square feet 
 

= thousandths of an inch 
 

= milliliters 

= modulus of elasticity 

= percent 

= points 

ACKNOWLEDGMENT 

The authors wish to acknowledge the 

contributions of Erwin E. Elert for preparing 

the pulp, Charles W. Polley for making the 

handsheets, and John F. Wichmann and 

Charles L. Coens for conducting the physical 

tests. 
PAPERMAKING FACTORS THAT INFLUENCE 

THE STRENGTH OF LINERBOARD WEIGHT 

HANDSHEETS 

By

JOHN W. KONING, JR., Technologist 

and 

JAMES H. HASKELL, Mathematical Statistician 

Forest Products Laboratory,1 Forest Service 

U.S. Department of Agriculture 

INTRODUCTION 
 

Burst strength and basis weight are the 

two material properties of major concern in 

the manufacture of linerboard for corrugated 

fiberboard. This is true primarily because 

these are the properties specified in the carrier regulations. Thus, the industry over the 

years has selected methods and techniques 

that produce linerboards which meet the requirements of burst and weight. However, it 

has been found that a container can have the 

proper burst and weight as required by the 

carrier regulations but still not necessarily 

perform well in the service environment. 

Greater emphasis is being placed on 

design of containers today to meet the specific end-use requirements of actual service 

conditions. Thus, there is a need to understand what can be done with existing equipment to improve the linerboard properties 

which actually relate to the performance of 

containers exposed to actual service conditions. Compressive strength properties are 

of particular interest. 

A major difficulty in solving this problem 

is that the actual service environment is not 

fully defined or understood. Consequently, 

adequate data are not available as to what 

paperboard properties are really essential or 

what minimum strength levels are required. 

Thus, this study explores the effects of 

typical papermaking factors on a number of 

strength properties that may be important, 

using nominal 42-pound-per-thousandsquare-foot (Ib/M ft2) handsheets made with 

varying types of fiber and varying types of 

papermaking equipment. To accomplish this, 

a statistically designed study was undertaken to evaluate the various papermaking 

factors such as wood species, pulp yield, 

type of refining, consistency at time of refining, degree of refining, wet-press pressure, 

and surface (varied by pressing the wet sheet 

against a blotter or a wire) on the strength 

properties of the handsheets. 

Another objective of this study is to help 

determine the effect of substituting other 

fibers such as hardwood on the properties of 

linerboard, and to determine the interaction 

of these fibers with some of the controllable 

papermaking operations. It is recognized that 

the results do not address the curvilinear 

response of some factors or the possibility 

that a change in the level of one of the factors could have a different significant effect. 

1 Maintained at Madison, Wis., in cooperation with the 

University of Wisconsin. 

2 Numbers in parentheses refer to literature cited at end 

of this report. 
MATERIAL AND PROCEDURES 
 


Two species of wood, southern pine and 

red oak, were selected because of the inherent difference in fiber morphology between the two, particularly in terms of fiber 

length and cell wall thickness. 

The wood was debarked and chipped to 

provide 518-in. chips for pulping by the kraft 

process. The southern pine and red oak 

chips were each pulped to two different yield 

levels, approximately 50 and 60 pct. The 

details of the pulping conditions are shown 

in table 1. The hot, softened chips were then 

fiberized in a disk mill and diluted to 3 pct 

consistency. 

Individual cooks of the same species 

were blended in a tank, dewatered to 25 pct 

consistency, and then separated into three 

different batches. One batch was diluted to 

approximately 18 pct consistency and refined in a 36-in. double-disk mill equipped 

with plates with no retaining rings. Another 

batch was diluted to 3 pct consistency with 

room temperature water and passed through 

the same disk refiner with the same plates, 

and the remaining one-third was diluted to 3 

pct and refined in a conical refiner equipped 

with a hydrating tackle. In each case, the 

pulp was refined to 450-ml and to 600-ml 

Canadian Standard freeness (CSF). 

These refined pulps were then made 

into 7- by 9-in. handsheets using a sheetmold 

with a 150-mesh screen. There was no circulation of white water, no pH adjustment, 

size, or alum added. The handsheets were 

couched off the mold with blotters, placed 

between blotters or between a blotter and a 

fine screen, and then placed in stacks of 

three or four and pressed at either 40 or 160 

Ib/in.2 

Wet-pressed handsheets were then 

dried using one drier of the experimental

paper machine. Each sheet was fed between 

the drier and drier felt, with the sheet reversed after each pass. This process was continued until the moisture content of the 

sheet was approximately 6 pct. The handsheets were conditioned at 73°F, 50 pct 

relative humidity, and evaluated for burst, 

thickness, weight, density, tear, fold, and 

ring crush according to TAPPI standards. 

Compressive strength was determined 

using the device developed by Jackson (2 2) 

and the tensile stress-strain properties, maximum stress, modulus of elasticity (MOE), 

and strain-to-failure, were determined using 

the method suggested by Setterholm (7) and 

modified by Jewett (3). Handsheet thickness 

was also determined using the stylus 

method developed at the Forest Products 

Laboratory by Setterholm (8). 

Table 1.—Pulping conditions for southern pine and red oak 

(sulfidity 25 pct) 

Digestion 

number 

NaOH 

(Na2O) 

Na2S 

(Na2O) 

Active 

alkali 

Liquor/ Time to Time at 

wood 170° C 170° C Yield Kappa 

number 

Pct Pct Pct Min. Min. Pct 

SOUTHERN PINE 

14-4543-6 12.0 4.0 16.0 4/1 90 75 49.3 52.7 

14-4547-50 10.875 3.625 14.5 4/1 90 30 60.2 118.0 

RED OAK 

14-4551-4 12.75 4.25 17.0 3.5/1 60 60 50.8 17.4 

14-4560-3 9.0 3.0 12.0 3.5/1 60 15 60.9 74.0 

-2-
 
EXPERIMENTAL DESIGN AND 
 


ANALYSIS 
 


To evaluate the various papermaking 

factors, a 27 full factorial design was initially 

planned. The factors and levels are as follows: 

Factor Level 

Wood species Southern pine 

Red oak 

Pulp yield Low (50 pct) 

High (60 pct) 

Consistency 3 pct 

18 pct 

Refiner Conical 

Disk 

Freeness (CSF) 450 ml 

600 ml 

Pressure 40 Ib/in.2 

160 Ib/in.2 

Surface Blotter 

Wire 

Because of the large quantity of data 

and the problems with coding, an analysis-ofmeans approach was used to analyze the 

data based on the work by Schilling (5, 6) and 

Nelson (4) in which the mean and standard 

deviation values were used instead of the individual values. This greatly speeded up the 

coding work and still allowed for the evaluation of the significant effects of the various 

parameters that were studied. 

The results are presented in tabular and 

graphic form. The graphs show the actual 

change in the properties by factors through a 

plotting program that allows for immediate 

indication of those factors that are both 

statistically and practically significant, their 

level, and their numerical difference. The 

numerical data are based on the average of 

10 replications except for the tensile properties which are based on the average of six 

replications. All the data have been standardized to a 42-lb handsheet weight to make 

direct comparisons. 

In analyzing each of the material properties, the response difference for the levels of 

each factor had to exceed 10 pct, based on 

the overall average, to be considered practically significant, and in addition that 10 pct 

had to be statistically significant at the 1 pct 

level. With this as the criterion, each of the 

material properties was analyzed for the effect of the factors. 

RESULTS 
 


As expected, freeness was one factor 

that significantly affected all properties of 

the linerboard except for tear, and generally 

in a positive manner-thatis, the handsheets 

made with pulp at 450 ml CSF were better 

than those made at 600 ml CSF. The other 

factor that significantly affected many of the 

strength properties was wet-press pressure. 

In this study, increasing the wet-press 

pressure resulted in improvements in the 

compressive, tensile, ring crush, and burst 

strengths, MOE, and folding endurance. 

Thickness, of course, was decreased with increased pressure. Increasing wet-press 

pressure generally resulted in the reduction 

of tear for handsheets made with southern 

pine pulp but had little effect or increased 

tear for handsheets made with red oak pulp. 

Wet-press pressure was the single biggest 

factor affecting the compressive strength 

properties.

As expected, wood species was a major 

factor in the strength properties. However, it 

depended on the particular species as to 

whether it was a positive or negative effect; 

for example, in general there was a reduction 

in tear, fold, burst, and tensile strain to 

failure for handsheets made with short 

fibers. On the other hand, the MOE increased 

using short fibers, and type of fiber was not a 

significant factor in terms of compressive 

strength. 

Results of these combinations along 

with the highest properties obtained for the 

particular wood species, yield, and freeness 

group are given in table 2. 

-3­
 
In analyzing all the results, there were 

virtually no surprises regarding major effects, although the influence of wet-press 

pressure was greater than expected, especially on compressive properties. Compressive strength was not significantly affected by yield; however, previous research 

(1) indicated that edgewise compressive 

strength of corrugated fiberboard may be 

adversely affected if the corrugated is made 

from high-yield pulp. 

As indicated previously, one object of 

this work is to help determine the effect of 

the interaction of various papermaking 

operations and fibers on a given linerboard 

property. Thus, the tables are organized to 

facilitate the making of these comparisons. 

Specific results are presented in these 

tables, one table for each property, so that 

direct comparison between any of the 

variables can be made (tables 3 to 14). 

Thus, if a linerboard is presently made 

using 100 pct, low-yield, southern pine– 

refined at 3 pct consistency in a double disk 

refiner to 600 ml CSF and wet-pressed with 

low pressure-and if it is desirable to improve compressive strength, table 3 can be 

used. In this table, the value 24.3 Ib/in. for 

this set of operating conditions is found, and 

this value can be compared with the results 

of any change in operation that is of interest. 

For example, by increasing the wet-press 

pressure, the compressive strength went to 

28.9; reducing the freeness and increasing 

the pressure, it went to 29.5. Likewise, one 

can get an estimate of what happens with a 

major change like switching to hardwood 

fiber. 

The levels of the factors that were 

studied were met except that there was a 

slight difference in the high consistency 

refining level–that is, 18 pct for the southern 

pine and 20 pct for the red oak-andin the 

variation in CSF which ranged from 430 to 

460 and 580 to 625 ml. Both of these variations were considered within experimental 

control. 

The original intent was to conduct experiments using the full factorial design. 

However, it was not possible to refine pulp at 

high consistency with the conical refiner so 

the data were analyzed in terms of the two 

types of refiners–at 3 pct consistency over 

-4­
 
all the other factors and then a separate 

analysis with the double disk at 3 and 18 pct 

consistency. Since the results were similar, 

only the statistical analysis for the two types 

of refiners is included. Also, the low-yield, 

red oak pulp had a CSF below 600 ml after 

fiberizing. Thus, it was not refined, and the 

same values are listed under both the 3 and 

18 pct consistencies for each of the two 

types of refiners. It was decided that this 

data was a better estimate of actual properties than were values which could be calculated by a statistical missing value program 

using the other actual data. 

The analysis of means results are given 

in a series of plots of property response versus factors (figs. 1 to 11). Each plot has the 

factor or interaction identified in terms of a 

letter or combination of letters (for instance, 

W–wood species, WY–wood species-yield 

interactions), direction of the effect, magnitude, and whether it is statistically significant. The small dashed lines on either side of 

Compressive Strength (Ib/in.2)

(Table 4, Fig. 2) 

These are the same values as given in 

table 3 but expressed in Ib/in.2 using the 

thickness measurement as determined by 

the FPL stylus method (8). Two factors, wetpress pressure and freeness, are significant. 

Increasing the wet-press pressure resulted in 

a compressive strength increase of 41 pct. 

Reducing the freeness from 600 to 450 ml 

resulted in a 24 pct increase in compressive 

strength. 

Ring Crush (Table 5, Fig. 3) 

As with the compressive strength,

freeness and wet-press pressure are significant factors. Reducing the freeness resulted 

in an 18 pct increase in ring crush and 

increasing the wet-press pressure resulted in 

an increase of 12 pct. 

the grand mean for the property are the 1 pct 

significance level for each of the factors or 

interactions. For example, in figure 1, the 

effect of wood species falls outside the 

dashed lines and is therefore statistically 

significant. However, because the practical 

effect was less than 10 pct it was not 

discussed further. Each plot contains all the 

main effects, two level interactions, and any 

significant three-level interactions. The nonsignificant three-level interactions and all 

higher-order interactions are not plotted. The 

darkened circles indicate practical significant effects (more than 10 pct). The ones of 

particular importance from the analysis are 

as follows: 

Tear (Table 6, Fig. 4) 

Three factors significantly affected tear: 

wood species, yield, and the interaction of 

species and pressure. The effect of wood 

species is evident from figure 4, which 

shows a 61 pct reduction in tear between 

long (southern pine) and short (red oak) fibers 

as expected. The change in yield from 60 to 

50 pct resulted in an average increase in tear 

of 18 pct. This is probably explained by the 

increase in fiber bonding with lower yield 

pulp. Since the species-pressure interaction 

is significant, further analysis is required. 

The data in table 6 indicates that, in general, 

increasing the pressure results in a decrease 

in tear for handsheets made with southern 

Compressive Strength (Ib/in. w) 

(Table 3, Fig. 1) 

pine but an increase in tear for those made 

from red oak pulp. 

Results indicate that two major factors 

affect compressive strength: wet-press pressure and freeness. With an increase in wetpress pressure from 40 to 160 lb/in.2, the 

overall average compressive strength increased 16 pct. With a reduction in freeness 

from 600 to 450 ml, the overall average compressive strength increased by 15 pct. No 

other factors or interactions affected the 

compressive strength significantly in terms 

of the arbitrary level of 10 pct. -5­

Modulus of Elasticity

(Table 7, Fig. 5) 

Four major factors significantly affected 

the MOE–species, yield, freeness, and wetpress pressure. On the average, the MOE improved 40 pct with an increase in wet-press 

pressure, 30 pct with the species change to 

short-fiber red oak, 20 pct with reduction in 

freeness, and 14 pct with a reduction in yield. 
Table 3.–Compressive strength (lb/in.) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double dish Conical Double dish 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 24.5 26.8 28.5 23.4 26.6 29.3 28.1 27.0 26.2 27.5 28.5 29.9 

(0.89) (1.13) (1.31) (1.10) (0.88) (0.42) (0.71) (0.72) (1.23) (0.52) (1.37) (1.15) 

Wire 23.9 27.0 28.3 24.1 25.3 28.8 25.6 26.2 25.1 25.5 30.2 29.1 

(1.46) (0.81) (0.91) (0.82) (1.28) (1.33) (0.85) (1.37) (2.42) (2.40) (1.69) (0.81) 

High pressure (160 lb/in.2) 

Blotter 	 28.7 29.5 30.9 29.4 30.1 31.4 30.8 31.6 28.9 31.6 32.4 33.7 

(1.69) (0.85) (0.91) (0.79) (1.16) (1.07) (2.00) (3.52) (1.69) (0.82) (1.28) (0.79) 

Wire 28.7 30.2 32.4 30.4 29.1 30.5 30.8 30.7 30.5 30.9 31.9 32.4 

(1.55) (0.72) (1.59) (1.41) (1.34) (0.69) (1.21) (0.74) (1.27) (1.17) (1.54) (2.00) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 21.4 24.3 25.3 22.0 24.2 26.4 421.9 421.9 421.9 24.3 21.0 21.5 

(0.83) (1.43) (0.61) (0.61) (0.92) (0.87) (1.17) (1.17) (1.17) (0.68) (1.47) (0.69) 

Wire 21.0 23.3 26.3 22.5 23.2 24.5 419.8 419.8 419.8 22.4 21.8 21.2 

(0.59) (1.14) (0.59) (0.75) (0.66) (1.09) (1.30) (1.30) (1.30) (0.46) (0.66) (0.99) 

High pressure (160 Ib/in.2) 

Blotter 26.3 28.9 29.2 25.9 26.2 27.8 426.5 426.5 426.5 27.2 26.2 25.6 

(0.76) (1.76) (0.56) (1.29) (0.86) (0.92) (1.47) (1.47) (1.47) (0.68) (0.90) (0.76) 

Wire 25.8 28.2 30.6 26.5 27.1 29.4 424.8 424.8 424.8 27.6 26.2 25.4 

(0.31) (0.96) (0.91) (1.36) (2.45) (0.99) (1.72) (1.72) (1.72) (0.60) (0.68) (0.86) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 1.–Effect of various factors on the compressive strength of 42-lb/M ft2 handsheets. The 

significant factors are freeness (F) and wet-press pressure (P) and are indicated by the filled 

symbols. Complete factorand level identification is as follows: 

Factor Level 

W Wood species P 

O 

Southern 

Red oak 

pine 

Y Pulp yield L 

H 

Low (50 pct) 

High (60 pct) 

R Refiner C Conical 

D Disk 

F Freeness (CSF) 4 

6 

450 ml 

600 ml 

P Pressure L 

H 

Low (40 lb/in.2) 

High (160 lb/in.2) 

S Surface B Blotter 

W Wire (M 146 577) 

-7-
 

Table 4.–Compressive strength (Ib/in.2) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double dish Conical Double dish 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 1,950 2,290 2,800 1,680 1,920 2,410 2,070 1,950 1,920 2,130 2,200 2,370 

(64.9) (144.0) (150.0) (124.0) (61.3) (51.2) (69.5) (58.6) (97.3) (45.7) (133.0) (97.5) 

Wire 1,860 2,340 2,730 1,810 1,820 2,460 1,910 1,920 1,860 2,050 2,280 2,350 

(132.0) (79.1) (89.5) (70.9) (87.2) (159.0) (76.1) (90.3) (204.0) (164.0) (129.0) (49.6) 

High pressure (160 Ib/in.2) 

Blotter 	 2,970 3,170 3,550 2,680 2,670 3,030 2,950 2,890 2,720 3,080 3,080 3,340 

(231.0) (121.0) (100.0) (130.0) (91.4) (117.0) (201.0) (327.0) (166.0) (86.6) (90.9) (138.0) 

Wire 2,970 3,270 3,530 2,930 2,760 3,000 2,990 2,930 2,810 3,050 3,070 3,180 

(195.0) (64.1) (140.0) (151.0) (94.9) (69.5) (152.0) (82.5) (72.4) (117.0) (160.0) (165.0) 

600 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 1,470 1,800 2,050 1,470 1,530 1,890 41,480 41,480 41,480 1,660 1,370 1,460 

(67.0) (77.6) (59.4) (56.0) (53.0) (53.4) (76.8) (76.8) (76.8) (51.2) (104.0) (55.6) 

Wire 1,490 1,730 2,210 1,570 1,510 1,750 41,350 41,350 41,350 1,630 1,410 1,480 

(49.5) (60.6) (69.2) (46.3) (36.6) (86.7) (80.9) (80.9) (80.9) (79.7) (69.4) (85.8) 

High pressure (160 lb/in.2) 

Blotter 2,480 2,740 3,100 2,150 2,050 2,370 42,350 42,350 42,350 2,420 2,230 2,180 

(114.0) (163.0) (71.0) (137.0) (93.1) (103.0) (138.0) (138.0) (138.0) (47.6) (94.8) (66.5) 

Wire 2,500 2,710 3,140 2,390 2,290 2,720 42,240 42,240 42,240 2,550 2,280 2,220 

(44.7) (130.0) (136.0) (154.0) (202.0) (89.3) (146.0) (146.0) (146.0) (59.1) (79.0) (94.7) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 2.–Effect of various factors on the compressive strength of 42-lb/M ft2 handsheets. The 

significant factors are freeness (F) and wet-press pressure (P) and are indicated by the filled 

symbols. (Factor identification as for fig. 1.) (M 146 576) 
Table 5.–Ring crush strength (lb) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 wt) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 115.6 117.2 135.4 123.0 121.0 133.5 104.4 108.7 102.2 112.9 121.1 126.6 

(6.62) (6.72) (7.82) (7.23) (6.04) (8.06) (3.90) (6.26) (4.45) (4.72) (4.33) (5.93) 

Wire 118.3 131.2 129.7 122.7 119.7 127.0 99.0 108.6 102.7 107.9 117.5 129.6 

(7.63) (4.76) (8.19) (6.12) (4.35) (8.78) (4.06) (6.13) (3.99) (9.14) (4.65) (3.13) 

High pressure (160 lb/in.2) 

Blotter 121.9 119.7 120.9 113.9 126.1 116.5 122.3 122.2 115.1 130.4 133.0 136.6 

(6.92) (9.74) (7.50) (8.77) (4.83) (4.70) (5.87) (5.76) (7.00) (7.32) (5.81) (3.95) 

Wire 111.8 121.7 120.0 111.6 124.3 119.2 118.2 124.3 122.6 116.5 125.5 126.5 

(8.25) (6.53) (4.01) (13.9) (8.60) (5.83) (9.32) (4.11) (6.15) (5.93) (13.00) (12.00) 

600 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 79.6 103.5 114.1 98.6 102.1 115.4 468.5 468.5 468.5 96.7 83.4 94.8 

(5.95) (3.08) (6.53) (3.13) (5.37) (3.31) (6.21) (6.21) (6.21) (5.69) (2.74) (3.46) 

Wire 96.9 104.0 116.7 100.9 103.4 115.8 469.8 469.8 469.8 90.5 85.8 89.1 

(3.16) (2.87) (4.98) (7.29) (3.38) (6.17) (3.33) (3.33) (3.33) (7.76) (8.13) (6.22) 

High pressure (160 Ib/in.2) 

Blotter 118.5 122.5 132.1 113.4 119.9 125.9 487.5 487.5 487.5 119.9 100.1 106.4 

(4.24) (7.07) (7.73) (7.35) (3.68) (4.30) (6.50) (6.50) (6.50) (3.93) (3.96) (8.43) 

Wire 111.1 115.3 118.3 113.2 123.2 125.3 493.4 493.4 493.4 114.4 104.2 111.1 

(8.79) (4.93) (3.23) (6.17) (7.23) (4.24) (3.53) (3.53) (3.53) (7.69) (6.84) (10.70) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 3.–Effect of various factors on the ring crush strength of 42-Ib/M ft2 handsheets. The 

significant factors are freeness (F) and wet-press pressure (P) and are indicated by the filled 

symbols. (Factor identification as for fig. 1.) 

(M 146 575) 
Table 6.–Tear strength (g) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double dish Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 367 386 402 289 347 345 207 216 204 170 167 192 

(16.3) (13.3) (15.4) (13.5) (13.0) (16.9) (11.8) (17.6) (19.3) (5.4) (8.6) (11.0) 

Wire 383 385 398 275 338 329 212 200 211 180 172 200 

(25.4) (13.3) (30.0) (12.0) (16.6) (15.4) (11.2) (12.4) (14.7) (8.6) (15.2) (19.7) 

High pressure (160 Ib/in.2) 

Blotter 331 358 377 268 308 301 221 244 220 165 184 188 

(15.5) (21.7) (22.5) (17.3) (9.3) (16.3) (17.1) (23.5) (10.8) (5.4) (17.6) (13.8) 

Wire 332 339 366 260 304 304 231 243 231 162 172 196 

(13.8) (23.2) (21.6) (27.9) (21.7) (10.7) (20.5) (11.5) (15.3) (7.4) (10.2) (11.0) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 387 400 419 305 341 347 4143 4143 4143 158 141 141 

(12.2) (10.0) (21.8) (22.4) (20.6) (22.1) (10.7) (10.7) (10.7) (7.8) (11.2) (9.4) 

Wire 384 404 415 301 332 338 4149 4149 4149 153 144 139 

(13.6) (17.0) (22.6) (15.9) (17.4) (11.4) (18.3) (18.3) (18.3) (7.4) (9.3) (8.6) 

High pressure (160 Ib/in.2) 

Blotter 362 362 353 280 312 310 4163 4163 4163 165 161 161 

(16.5) (11.2) (14.3) (15.3) (11.9) (4.2) (13.6) (13.6) (13.6) (9.4) (11.0) (7.9) 

Wire 339 344 344 266 302 300 4196 4196 4196 167 162 162 

(13.6) (11.9) (14.2) (10.1) (9.1) (15.8) (24.2) (24.2) (24.2) (6.7) (9.3) (6.7) 

1 Numbers in parentheses are standard deviation. 

2 Percent consistency. 

3 Canadian Standard. ml. 

4 Pulps not refined (CSF was below 600 after fiberizing). 
Figure 4.–Effect of various factors on the tear strength of 42-lb/M ft2 handsheets. The significant 

factors are wood species (W), yield (Y), and the wood-pressure (WP) interaction and are indicated by the filled symbols. (Factor identification as for fig. 1.) (M 146 574) 
Table 7.–Modulus of elasticity (ksi) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 362 441 431 281 308 396 452 512 482 480 444 538 

(24.7) (49.8) (32.8) (33.2) (23.0) (22.0) (16.5) (61.3) (60.8) (15.9) (21.8) (38.6) 

Wire 332 440 486 283 321 410 518 461 489 440 480 474 

(50.5) (24.8) (36.8) (25.1) (24.6) (60.2) (106.0) (27.8) (34.9) (16.2) (93.2) (34.9) 

High pressure (160 Ib/in.2) 

Blotter 553 595 554 454 434 494 800 650 722 694 735 680 

(37.1) (40.4) (95.8) (37.8) (35.2) (59.7) (45.1) (44.5) (81.3) (92.3) (69.6) (42.5) 

Wire 577 598 570 474 421 517 683 754 692 647 622 670 

(29.7) (27.4) (72.6) (38.6) (26.7) (56.5) (26.6) (82.0) (87.1) (52.8) (60.3) (38.4) 

600 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 266 306 364 258 230 296 4368 4368 4368 368 380 359 

(16.7) (21.1) (13.5) (40.8) (15.1) (11.0) (17.3) (17.3) (17.3) (32.2) (27.9) (50.0) 

Wire 278 334 363 244 239 267 4434 4434 4434 370 359 328 

(12.4) (26.3) (30.6) (17.4) (16.6) (23.0) (69.9) (69.9) (69.9) (15.9) (40.6) (19.1) 

High pressure (160 Ib/in.2) 

Blotter 442 496 541 376 362 381 4578 4578 4578 557 546 468 

(25.6) (28.1) (14.1) (38.2) (25.8) (22.7) (30.1) (30.1) (30.1) (50.4) (54.1) (24.9) 

Wire 452 500 550 436 394 432 4619 4619 4619 559 485 477 

(47.4) (55.5) (48.5) (28.6) (41.8) (30.5) (108.0) (108.0) (108.0) (16.5) (39.0) (24.2) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing) 
 
Figure 5.–Effect of various factors on the MOE of 42-Ib/M ft2 handsheets. The significant factors 

are wood species (W), yield (Y), freeness (F), and wet-press pressure (P) and are indicated by 

(M 146 573) the filled symbols. (Factor identification as for fig. 1.) 
Tensile Strength (Ib/in.2

) (Table 8, Fig. 6) 

The results indicate that four factors 

and one interaction affect the tensile 

strength: species, yield, freeness, pressure, 

and the species-yield interaction. The wetpress pressure was the most significant: a 48 

pct increase in tensile strength occurred 

with an increase in wet-press pressure. 

Reducing freeness resulted in a 30 pct increase. With southern pine, lowering the 

yield resulted in a significant increase in tensile strength, but with red oak there was a 

reduction in tensile strength (table 8). 

Tensile Strain to Failure 

(Table 9, Fig. 7) 

Freeness, species, and the interaction 

between species and yield had significant effects on tensile strain to failure. The type of 

wood fiber had a 60 pct effect, but the presence of the interaction with yield indicates 

that yield is important depending on species. 

Results indicate that, in general, handsheets 

made from low-yield southern pine have 

greater strain to failure than those made from 

high yield, whereas for short-fiber red oak the 

reverse is true. As the CSF was reduced from 

600 to 450 ml the strain was increased 17 pct. 

Burst (Table 10, Fig. 8) 

Four factors and one interaction 

significantly affected the burst strength. The 

four factors were: species, yield, freeness, 

and pressure. The interaction was speciesyield. Changing from southern pine to oak 

resulted in a reduction in burst. Reducing the 

yield resulted in an increase in burst for the 

handsheets made from southern pine but the 

reverse was true for the handsheets made 

from red oak in most of the comparisons. 

As was expected, as the freeness was decreased, the burst increased, and as the wetpress pressure was increased, the burst increased. 

Folds (Table 11, Fig. 9) 

The property of fold is characterized by a 

number of factors and interactions, the most 

significant ones being the wood species, 

yield, wet-press pressure, and the interaction 

of yield and species. Obviously, the handsheets made with southern pine fiber had 

significantly higher folding endurance than 

the ones made from red oak. However, for the 

southern pine, a decrease in yield resulted in 

an increase in folds, whereas for the red oak, 

a decrease in yield resulted in a reduction in 

folds. Increasing the wet-press pressure increased the folds an average of 30 pct, but in 

some instances 10 times, such as with highyield red oak, disk refined to 600 ml CSF at 3 

pct consistency. Using the 10 pct criterion, a 

number of other factors and interactions, including the only three-level interactions in 

the study, were found to be significant: 

refiner, wood species-refiner, wood speciesyield-refiner, freeness, wood species-freeness, wood species-yield-freeness, wood 

species-yield-pressure, wood species-freeness-pressure, and surface. Folding endurance was the only property that was affected 

by surface, with the wire resulting in higher 

values than the blotter in most comparisons. 

Thickness (TAPPI and FPL) (Tables 

12 and 13, Figs. 10 and 11) 

As obvious from figures 10 and 11, the 

two significant factors that affect thickness 

are wet-press pressure and freeness. Increasing the wet-press pressure from 40 to 160 

Ib/in.2 resulted in a decrease in thickness of 

22 pct. Reducing the CSF from 600 to 450 ml 

resulted in a reduction of handsheet thickness of approximately 10 pct. Effect of the 

variables was essentially the same on both 

the FPL and TAPPI thickness measurements. 

Density (Table 14) 

The density of the various handsheets is 

given in table 14. 

-16-
 

SUMMARY 

Considering the data in terms of papermaking combinations that result in handsheets with high strength properties, the 

following emerged. Low-yield, southern pine 

pulp, refined in a disk mill at 3 pct consistency to 450 ml CSF and formed using high 

wet-press pressure, was of approximately 

equal quality-dependingon which properties are considered the most important-as 

the low-yield, southern pine pulp, refined in a 

disk mill at 18 pct consistency to 600 ml CSF 

and formed using high wet-press pressure. If 

tear is not important, the handsheets made 

from high-yield red oak, refined with a disk 

refiner at 20 pct consistency to 450 ml CSF 

and formed using high wet-press pressure, 

had surprisingly good properties. These red 

oak sheets, in fact, were better than the 

handsheets made with high-yield southern 

pine except for tear, burst, and tensile strain 

to failure. 

-17-
 

Table 8.–Tensile strength (lb/in.2) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical 

refiner 

Double disk 

refiner 

Conical 

refiner 

Double disk 

refiner 

Conical 

reliner 

Double dish 

refiner 

Conical 

refiner 

Double disk 

refiner 

450 Freeness3 

23 23 218 23 23 218 23 23 220 23 23 220 

LOW pressure (40 lb/in.2) 

Blotter 4,930 5,690 5,960 3,440 3,710 4,550 3,720 4,120 3,730 4,160 4,160 4,580 

(256) (560) (222) (197) (184) (195) (173) (401) (141) (127) (149) (447) 

Wire 4,550 5,820 6,160 3,560 3,980 5,080 3,940 3,770 3,870 4,100 4,490 4,740 

(341) (364) (429) (173) (179) (515) (736) (318) (411) (85) (444) (293) 

High pressure (160 lb/in.2) 

Blotter 7,280 8,360 8,470 5,530 5,720 6,160 6,910 6,330 6,380 6,340 6,840 7,220 

(419) (162) (395) (680) (286) (629) (759) (245) (455) (485) (215) (334) 

Wire 7,740 8,740 8,310 6,048 5,230 6,660 7,230 7,070 6,580 6,720 6,590 7,570 

(425) (609) (267) (187) (912) (93) (609) (935) (289) (476) (222) (309) 

600 Freeness3 

LOW pressure (40 Ib/in.2) 

Blotter 3,440 4,370 4,840 2,930 2,930 3,670 42,430 42,430 42,430 2,790 2,420 2,940 

(115) (154) (205) (271) (147) (119) (120) (120) (120) (77) (143) (185) 

Wire 3,480 4,470 4,940 3,220 3,030 3,520 42,570 42,570 42,570 3,140 2,420 2,670 

(137) (279) (315) (108) (169) (48) (115) (115) (115) (78) (99) (94) 

High pressure (160 Ib/in.2) 

Blotter 5,630 6,940 7,180 4,670 4,430 4,850 44,540 44,540 44,540 4,830 4,270 4,230 

(416) (223) (302) (195) (457) (244) (395) (395) (395) (240) (165) (231) 

Wire 5,970 7,500 8,120 5,520 4,880 5,630 44,490 44,490 44,490 5,280 4,540 4,510 

(632) (253) (850) (531) (218) (249) (623) (623) (623) (328) (297) (130) 

1 Numbers in parentheses are standard deviation. 

2 Percent consistency. 

3 Canadian Standard, ml. 

4 Pulps not refined (CSF was below 600 after fiberizing). 
Figure 6.–Effect of various factors on the tensile strength of 42-lb/M ft2 handsheets. The significant factors are wood species (W), yield (Y), freeness (F), wet-press pressure (P), and the wood 

species-yield (WY) interaction and are indicated by the filled symbols. (Factor identification 

asforfig. 1.) (M 146 569) 
Table 9.–Tensile strain to failure (pct) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 9.35 8.42 11.00 7.75 7.03 8.88 4.58 4.22 4.23 5.15 4.84 5.49 

(0.53) (0.56) (0.83) (1.38) (0.83) (0.30) (0.33) (0.38) (0.32) (0.40) (0.32) (0.28) 

Wire 9.46 9.10 10.97 7.88 8.08 9.43 3.72 4.45 4.05 5.33 5.28 5.78 

(0.72) (0.36) (1.06) (1.11) (0.60) (0.44) (0.80) (0.51) (0.55) (0.58) (0.28) (0.26) 

High pressure (160 lb/in2) 

Blotter 9.03 8.87 11.45 6.85 7.81 9.19 4.40 5.10 4.64 5.77 5.41 6.21 

(0.46) (0.63) (0.35) (2.02) (0.27) (0.80) (0.93) (0.23) (0.38) (0.38) (0.38) (0.50) 

Wire 9.56 9.39 11.60 9.23 7.25 10.76 5.30 4.74 5.17 6.11 5.65 6.78 

(0.60) (0.44) (0.41) (0.97) (1.89) (0.59) (0.56) (0.49) (0.33) (0.26) (0.28) (0.38) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 7.85 8.16 8.92 7.07 6.75 8.41 42.91 42.91 42.91 3.79 3.45 3.93 

(0.42) (0.28) (0.34) (1.22) (0.82) (0.41) (0.30) (0.30) (0.30) (0.38) (0.33) (0.23) 

Wire 7.97 8.18 9.00 8.52 7.22 8.29 43.04 43.04 43.04 4.44 3.82 3.83 

(0.36) (0.41) (0.48) (0.56) (0.85) (0.46) (0.14) (0.14) (0.14) (0.34) (0.21) (0.38) 

High pressure (160 lb/in.2) 

Blotter 7.28 8.10 9.35 7.49 6.84 8.05 43.39 43.39 43.39 4.56 4.23 4.10 

(0.81) (0.20) (0.66) (0.44) (1.27) (0.72) (0.57) (0.57) (0.57) (0.36) (0.28) (0.53) 

Wire 8.05 8.30 9.48 8.32 7.20 8.87 43.09 43.09 43.09 5.07 4.43 4.73 

(0.61) (0.47) (0.42) (1.25) (0.53) (0.41) (0.61) (0.61) (0.61) (0.48) (0.32) (0.25) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 7.–Effect of various factors on the tensile strain to failure of a 42-Ib/M ft2 handsheet. The 

significant factors are wood species (W), freeness (F), and the wood species-yield (WY) interaction and are indicated by the filled symbols. (Factor identification as for fig. (M 146 579) 
Table 10.–Burst strength (pt) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

LOW pressure (40 Ib/in.2) 

Blotter 169 184 200 128 138 143 100 91 89 100 107 117 

(6.7) (11.0) (10.0) (7.1) (10.0) (8.2) (6.2) (4.7) (6.6) (4.3) (7.5) (6.6) 

Wire 175 198 205 124 136 150 102 101 94 97 112 116 

(8.9) (11.0) (9.5) (9.3) (8.4) (7.8) (7.7) (8.4) (9.2) (11.0) (8.1) (6.6) 

High pressure (160 Ib/in.2) 

Blotter 200 213 215 149 148 162 136 128 122 129 141 152 

(11.0) (10.0) (11.0) (12.0) (12.0) (9.7) (11.0) (7.5) (7.6) (5.1) (9.9) (6.2) 

Wire 207 221 227 152 167 172 155 138 140 133 156 162 

(8.6) (12.0) (11.0) (9.1) (9.9) (9.7) (14.0) (13.0) (11.0) (9.9) (17.0) (9.2) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 136 169 169 124 121 132 455 455 455 72 62 71 

(8.8) (9.3) (9.3) (8.5) (8.9) (6.4) (2.8) (2.8) (2.8) (5.6) (2.5) (3.5) 

Wire 143 167 180 125 126 129 459 459 459 80 66 69 

(7.6) (8.1) (7.5) (7.7) (5.3) (8.1) (2.6) (2.6) (2.6) (5.2) (3.6) (3.2) 

High pressure (160 Ib/in.2) 

Blotter 162 192 200 142 142 148 485 485 485 103 85 94 

(9.8) (13.0) (12.0) (4.8) (7.4) (13.0) (8.1) (8.1) (8.1) (7.6) (6.3) (6.8) 

Wire 	 182 199 207 152 156 164 493 493 493 118 100 106 

(8.9) (11.0) (9.2) (12.0) (12.0) (8.7) (7.5) (7.5) (7.5) (5.8) (8.3) (6.1) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard. ml. 
 

4 Pulps not relined (CSF was below 600 alter fiberizing). 
 
Figure 8.–Effect of various factors on the burst strength of 42-Ib/M ft2 handsheets. The significant 

factors are wood species (W), yield (Y), freeness (F), wet-press pressure (P), and the wood 

species-yield (WY) interaction and are indicated by the filled symbols. (Factor identification 

as for fig. 1.) (M 146 570) 
Table 11.–Folding endurance of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double dish Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 1,845 2,886 2,049 696 1,045 1,085 59 28 30 230 164 447 

(438.0) (475.0) (413.0) (83.6) (206.0) (137.0) (11.7) (4.3) (3.3) (71.9) (29.3) (92.6) 

Wire 2,135 2,764 1,941 644 1,099 963 73 46 53 314 309 661 

(166.0) (435.0) (161.0) (117.0) (116.0) (219.0) (14.3) (9.8) (14.6) (89.4) (120.0) (242.0) 

High pressure (160 lb/in.2) 

Blotter 2,132 2,364 2,452 681 1,090 962 260 139 126 854 862 965 

(234.0) (432.0) (576.0) (134.0) (146.0) (194.0) (77.7) (37.3) (45.0) (274.0) (229.0) (148.0) 

Wire 2,332 2,934 2,886 902 1,134 1,180 469 263 285 1,209 1,501 1,857 

(245.0) (432.0) (211.0) (169.0) (85.6) (488.0) (143.0) (49.9) (72.0) (306.0) (261.0) (430.0) 

600 Freeness3 

Low pressure (40 lb/in.2) 

Blotter 1,681 2,145 2,153 712 878 884 47 47 47 56 24 44 

(266.0) (621.0) (308.0) (53.7) (134.0) (139.0) (1.1) (1.1) (1.1) (10.8) (4.3) (12.5) 

Wire 1,880 2,536 2,617 807 914 922 49 49 49 59 36 38 

(209.0) (236.0) (448.0) (269.0) (109.0) (165.0) (3.7) (3.7) (3.7) (16.7) (6.9) (11.7) 

High pressure (160 lb/in.2) 

Blotter 2,333 2,733 3,065 838 966 1,075 429 429 429 364 247 235 

(422.0) (524.0) (423.0) (194.0) (282.0) (142.0) (6.4) (6.4) (6.4) (128.0) (61.3) (55.2) 

Wire 2,247 3,105 3,390 976 1,183 1,276 448 448 448 574 364 414 

(330.0) (552.0) (243.0) (57.7) (327.0) (241.0) (7.2) (7.2) (7.2) (165.0) (112.0) (121.0) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 9.–Effect of various factors on the folding endurance of 42-Ib/M ft2 handsheets. The four 

most significant factors are wood species (W), yield (Y), pressure (P), and the wood speciesyield (WY) interaction and are indicated by the filled symbols. (Factor identification as for fig. 

1.) 

(M 146 578) 
Table 12.–TAPPI thickness (mil) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double dish Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

LOW pressure (40 Ib/in.2) 

Blotter 13.1 12.7 11.7 14.5 14.6 13.1 14.6 14.8 15.2 14.4 14.3 13.9 

(0.37) (0.21) (0.47) (0.25) (0.44) (0.38) (0.14) (0.34) (0.52) (0.41) (0.44) (0.41) 

Wire 13.7 12.7 11.8 14.9 14.2 13.2 14.4 14.6 14.5 14.2 13.9 13.7 

(0.45) (0.23) (0.30) (0.57) (0.24) (0.36) (0.62) (0.32) (0.28) (0.17) (0.27) (0.21) 

High pressure (160 Ib/in.2) 

Blotter 11.0 10.5 10.4 12.1 12.2 11.3 11.2 11.5 11.4 12.4 11.6 11.5 

(0.35) (0.24) (0.46) (0.39) (0.28) (0.21) (0.20) (0.14) (0.19) (0.59) (0.34) (0.34) 

Wire 11.0 10.5 10.2 11.9 11.8 11.4 11.7 11.5 11.4 11.9 11.5 11.9 

(0.40) (0.25) (0.18) (0.52) (0.33) (0.37) (0.42) (0.14) (0.40) (0.28) (0.29) (0.46) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 16.5 13.7 13.2 16.1 16.3 14.5 416.4 416.4 416.4 15.5 16.4 16.2 

(0.74) (0.20) (0.58) (0.46) (0.38) (0.23) (0.29) (0.29) (0.29) (0.37) (0.25) (0.28) 

Wire 15.8 14.8 13.1 15.6 16.7 14.6 415.9 415.9 415.9 15.3 16.1 15.8 

(0.64) (0.31) (0.52) (0.56) (0.55) (0.19) (0.30) (0.30) (0.30) (0.50) (0.30) (0.32) 

High pressure(160 Ib/in.2) 

Blotter 11.6 11.3 10.8 13.2 13.5 12.4 412.3 412.3 412.3 12.6 13.0 13.2 

(0.25) (0.25) (0.35) (0.20) (0.35) (0.26) (0.13) (0.13) (0.13) (0.53) (0.35) (0.30) 

Wire 12.2 11.5 10.6 12.2 12.5 11.6 412.5 412.5 412.5 12.4 12.9 13.2 

(0.36) (0.24) (0.20) (0.26) (0.22) (0.25) (0.29) (0.29) (0.23) (0.25) (0.19) (0.27) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent consistency. 
 

3 Canadian Standard. ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 10.–Effect of various factors on the TAPPI thickness of 42-Ib/M ft2 handsheets. The significant factors are freeness (F) and wet-press pressure (P) and are indicated by the filled symbols. (Factor identification as for fig. 1.) (M 146 571) 
Table 13.–FPL thickness (mil) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Double disk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 12.5 11.8 10.2 14.1 13.9 12.1 13.5 13.9 13.5 12.9 12.9 12.6 

(0.17) (0.32) (0.22) (0.60) (0.40) (0.15) (0.31) (0.16) (0.22) (0.13) (0.29) (0.40) 

Wire 12.9 11.5 10.3 13.3 13.8 11.7 13.4 13.7 13.5 12.5 13.2 12.3 

(0.37) (0.16) (0.21) (0.27) (0.32) (0.34) (0.26) (0.21) (0.33) (0.22) (0.14) (0.15) 

High pressure (160 Ib/in.2) 

Blotter 9.6 9.4 8.7 11.0 11.3 10.4 10.4 11.0 10.6 10.2 10.5 10.1 

(0.30) (0.22) (0.14) (0.35) (0.30) (0.23) (0.10) (0.09) (0.19) (0.10) (0.14) (0.24) 

Wire 9.7 9.2 9.2 10.4 10.5 10.2 10.4 10.5 10.9 10.2 10.4 10.1 

(0.23) (0.11) (0.16) (0.22) (0.21) (0.33) (0.21) (0.09) (0.26) (0.17) (0.06) (0.13) 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 	 14.7 13.4 12.3 15.0 15.8 13.9 414.8 414.8 414.8 14.7 15.3 14.6 

(0.24) (0.21) (0.24) (0.55) (0.27) (0.20) (0.27) (0.27) (0.27) (0.05) (0.26) (0.10) 

Wire 14.2 13.4 12.0 14.4 15.4 14.1 414.6 414.6 414.6 13.7 15.4 14.3 

(0.36) (0.32) (0.31) (0.21) (0.21) (0.19) (0.16) (0.16) (0.16) (0.50) (0.34) (0.21) 

High pressure (160 Ib/in.2) 

Blotter 10.7 10.6 9.4 12.1 12.8 11.8 411.3 411.3 411.3 11.2 11.7 11.7 

(0.23) (0.15) (0.14) (0.39) (0.23) (0.30) (0.18) (0.18) (0.18) (0.10) (0.19) (0.05) 

Wire 10.3 10.4 9.8 11.1 11.8 10.8 411.2 411.2 411.2 10.9 11.5 11.4 

(0.18) (0.19) (0.19) (0.32) (0.32) (0.20) (0.18) (0.18) (0.18) (0.31) (0.15) (0.17) 

1 Numbers in parentheses are standard deviation. 
 

2 Percent Consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Figure 11.–Effect of various factors on the FPL thickness of 42-Ib/M ft2 handsheets. The significant factors are freeness (F) and wet-press pressure (P) and are indicated by the filled symbols. (Factor identification as for fig. 1.) (M 146 572) 
Table 14.–Density (g/cc) of 42-lb/M ft2 handsheets1 

Southern pine kraft Red oak kraft 

Low yield (49.3 pct) High yield (60.2 pct) Low yield (50.8 pct) High yield (60.9 pct) 

Conical Double disk Conical Doubledisk Conical Double disk Conical Double disk 

refiner refiner refiner refiner refiner refiner refiner refiner 

23 23 218 23 23 218 23 23 220 23 23 220 

450 Freeness3 

Low pressure (10 Ib/in.2) 

Blotter 0.64 0.66 0.76 0.58 0.58 0.68 0.60 0.60 0.60 0.66 0.63 0.66 

Wire 0.63 0.69 0.76 0.60 0.60 0.69 0.62 0.59 0.61 0.65 0.62 0.68 

High pressure (160 lb/in.2) 

Blotter 0.83 0.84 0.91 0.76 0.71 0.81 0.79 0.75 0.78 0.78 0.79 0.81 

Wire 0.87 0.88 0.89 0.77 0.73 0.83 0.80 0.77 0.77 0.80 0.77 0.81 

600 Freeness3 

Low pressure (40 Ib/in.2) 

Blotter 0.56 0.58 0.66 0.55 0.51 0.57 40.54 40.54 40.54 0.56 0.54 0.56 

Wire 0.55 0.59 0.66 0.57 0.51 0.57 40.54 40.54 40.54 0.60 0.53 0.56 

High pressure (160 lb/in.2) 

Blotter 0.76 0.77 0.82 0.68 0.65 0.70 40.71 40.71 40.71 0.73 0.69 0.71 

Wire 0.77 0.81 0.85 0.76 0.67 0.74 40.72 40.72 40.72 0.71 0.71 0.72 

1 Based on FPL thickness measurements 
 

2 Percent consistency. 
 

3 Canadian Standard, ml. 
 

4 Pulps not refined (CSF was below 600 after fiberizing). 
 
Literature Cited 
 

1. Byrd, V. L., and J. W. Koning, Jr. 

1978. 	 Edgewise compressive creep of 

various corrugated fiberboards in 

cyclic RH environments. TAPPI 

61(6):35-37. 

2. 	 Jackson, C. A., J. W. Koning, Jr., and W. A. 

Gatz. 

1976. 	 Edgewise compressive test of 

paperboard by a new method. Pulp 

and Paper of Canada 77(10):43-46. 

3. Jewett, D. M. 

1963. 	 An electrical strain gage for the 

tensile testing of paper. U.S. Forest 

Serv. Res. Note FPL-03. Forest Products Laboratory, Madison, Wis. 

4. 	 Nelson, L. S. 

1974. Factors for the analysis of means. 

J. Quality Tech. 6(4):175-181. 

5. Schilling, E. G. 

1973. 	 A systematic approach to the 

analysis of means, Part I: Analysis of 

treatment effects. J. Quality Tech. 

5(3):93-107. 

6. Schilling, E. G. 

1973. 	 A systematic approach to the 

analysis of means, Part II: Analysis of 

contrasts. Part III: Analysis of nonnormal data. J. Quality Tech. 

5(4):147-159. 

7. Setterholm, V. C., and E. W. Kuenzi. 

1956. U.S. Forest Prod. Lab. Report 2066. 

Forest Products Laboratory, Madison, 

Wis. 

8. Setterholm, V. C. 

1974. A new concept in paper thickness 

measurement. TAPPI 57(3):164. 

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U.S. GOVERNMENT PRINTING OFFICE: 1979–651-061