YIELD AND STRENGTHOF SOFTWOOD DIMENSION

LUMBER PRODUCEDBY EGAR SYSTEM

USDA FOREST SERVICERESEARCH PAPER

FPL 2931977

U.S. DEPARTMENT OF AGRICULTUREFOREST SERVICE

FOREST PRODUCTS LABORATORYMADISON, WIS.

ABSTRACT

Approximately 20 billion board feet ofsoftwood dimension lumber is manufacturedannually in the United States by systems thatwaste considerable potentially usable materialin ripping and edging of cants and flitches tofixed widths.

The Edge-Glue-and-Rip (EGAR) system isdesigned to use the full width of each flitchsawn from a log by live sawing logs, dryinground-edge flitches, ripping to the widest pos-sible usable width, edge gluing into panels 36to 48 inches wide, and ripping the panels tof inal dry widths for softwood dimensionlumber. The panels are ripped to yield lumberthat reflects the highest grade and strengthpotential within the panel. The effect of knots isminimized by placing them away from theedges and containing the large knots in widerlumber.

With the EGAR system, size of log doesnot restrict the width of lumber. The systemlends itself well to automated scanning andcomputer ripping decisionmaking. A signifi-cant increase in overall yield of 10 percent wasrecorded for lumber produced by the EGARsystem over standard lumber. It was also sig-nificantly higher in modulus of rupture thanstandard. EGAR lumber showed less warp andwas of higher visual grade than standardlumber, but in neither case was the differencestatistically significant. Data indicate thatEGAR had slightly higher stiffness properties,but the difference was not significant.

YIELD AND STRENGTHOF SOFTWOOD DIMENSIONLUMBER PRODUCEDBY EGAR SYSTEM

BYKENNETH C. COMPTON, Forest Products TechnologistHIRAM HALLOCK, Forest Products TechnologistCHARLES GERHARDS, EngineerandRONALD JOKERST, Forest Products TechnologistForest Products Laboratory,1 Forest ServiceU.S. Department of Agriculture

INTRODUCTION

Some 20 billion board feet of softwooddimension lumber is now used annually in theUnited States for housing, commercial con-struction, and industrial uses. If consumptioncontinues to increase annually at the presentrate, a shortage of softwood lumber before theyear 2000 is forecast. If that rate rises evenfaster, a shortage could occur in the nextdecade. The U.S. Forest Products Laboratoryis involved in a national effort to increase thesupply of softwood timber products. At thesame time, the timber resource must not bedestroyed and the quality of the environmentmust be enhanced.

To improve manufacturing efficiency thatwill better utilize the timber resource and ex-tend the supply, research in new and improvedsystems of sawing and secondary processingis underway.

EGAR SystemOne of the systems tested for processing

timber into lumber has been named Edge-Glue-and-Rip (EGAR). Basically, EGAR at-tempts to eliminate the losses that occur dur-ing the conventional manufacturing system ofedging green flitches to standard widths. In theEGAR system the green, round-edged flitchesare dried, ripped to the widest width possible,and edge-glued into panels that are ripped tofinished dimension widths.

A modification of the system would be torough-edge green flitches with ripsaws orchipper-edgers, dry, re-edge, and glue intopanels. Either way, the entire EGAR system formanufacturing softwood dimension lumber istechnically feasible with present equipment.

In addition to the anticipated benefit fromincreased volume yield of softwood dimensionlumber, a potential exists to increase quality.Panels can be ripped to minimize the effect ofknots and other defects. Warp can be reducedand the width of lumber is no longer restrictedby log diameter. Panels can be stored and cutto customers’ orders. The potential for a defectscanner and computer control of rippingpresents a further possibility for control ofproduct mix and quality.

Objectives and ScopeThe study was designed to examine the

feasibility of gluing square-edge softwoodflitches, nominally 8/4 thick, to:

Compare volume yields of 8/4 softwooddimension lumber manufactured by thestandard process and by the EGARsystem.

1Maintained at Madison, Wis., in cooperation with theUniversity of Wisconsin.FPL 293

Examine yield by grade, degree of warp,and comparative mechanical charac-teristics of solid lumber and lumbermanufactured by the EGAR system.

The study was limited to one species--shortleaf pine.

STUDY PROCEDURE

MaterialEighteen shortleaf pine logs, 33 feet (ft)

long, were purchased from the WeyerhaeuserCompany at Mt. Pine, Ark. To eliminate theeffect that variables such as rot, shake, andscars have on yield and quality of dimensionlumber, logs were chosen that were free ofdefects except for knots. Straightness was alsoa criterion, but here effect of moderate sweepwould be minimal because the 33-ft logs werebucked to nominal 8-ft lengths. The only othercriterion applied in selecting logs was topdiameter (6-13 in.).

The logs were stored under water spray atthe Forest Products Laboratory before buck-ing to 8-ft 3-in. lengths. As the logs were deliv-ered to the sawmill log deck, the sawing pat-tern was stenciled with indelible pencil on thesmall end of each log using a template (fig. 1).

Figure 1.--Stenciling the sawing pattern on thesmall end of the logs. Log already markedhas sawline through middle of log perpen-dicular to the short axis.

(M 141 260-3)

The template was made of thin fiberboard withparallel sawline slots 9/32 in. wide, separatedby strips 1-25/32 in. wide, which representedthe green target thickness for 8/4 southernpine dimension lumber. The template wasplaced on the face with the sawlines perpen-dicular to the short axis. It was moved to oneside or the other until equal slab faces at least4 in. wide were visible in the outer sawline slotsin the template. This method resulted in twopatterns. One sawline was through the centerof the log, or a sawline on each side was equi-distant from the center of the log. Results ofmathematical modeling2 indicate that thismethod yields the greatest possible total widthof flitches when live sawing the log (throughand through).

Sawing and DryingThe logs were sawed on the Forest Prod-

ucts Laboratory’s circular sawmill, cutting 1-25/32-in. thickness for each flitch and 9/32 in.for saw kerf (fig. 2). Flitches were numberedconsecutively, beginning with the first flitchfrom the first log and ending with the last flitchfrom the last log. All were measured on thenarrow face at the narrowest point between thebark. By coin flip, the even-numbered flitcheswere chosen for standard manufacturingprocedure, and they were edged (fig. 3) togreen target widths to yield standard drysoftwood dimension lumber according to theAmerican Softwood Lumber Standards.3

NominalWidth

GreenTargetWidth

ALS Dry-DressedWidth3

For this study no wane was permitted onedged standard lumber nor was it permitted inmeasuring EGAR flitch widths. This was doneto eliminate wane as a variable since it couldbe a subjective element in measuring total

2Unpublished research at FPL to evaluate EGARpotential.

3American Softwood Lumber Standard, NBS Volun-tary Product Standard PS 20-70, U.S. Department ofCommerce, January 1970.

2

Figure 2.--Marked logs were sawed live withopposite faces at least 4 in. wide andparallel to the long axis.

(M 141 260-9)

yield and establishing the grade. The narrow-est EGAR flitch width that was accepted was3.9 in., the same as the green target size forstandard 4-in. lumber. After eliminating pieceswith less than the allowable width, there were121 EGAR and 127 standard flitches.

Figure 3.--Illustrates loss of material whenedging green flitches to widths for stand-ard lumber with allowances for shrinkage,planing, and sawing variation.

(M 141 261-8)

The EGAR flitches and standard lumberwere kiln dried to 12 percent (pct) moisturecontent. Because the round-edge flitches oc-cupied approximately 60 pct more space in thedry kiln, a piling arrangement alternating twolayers of them to one layer of edged standardlumber was used (fig. 4). Approximately 2,000pounds (lb) of iron weights (about 30 Ibs/ft2)were laid on top of the pile.

An elevated-temperature schedule wasused for drying. Maximum temperature was205° F and maximum depression was 85° F.After drying, all lumber was conditioned andequalized at 190° F dry bulb and 185° F wetbulb for an EMC of 14 pct.

In practice, kiln space could be saved byrough-edging the EGAR flitches either bysawing or chipping. This would require an-other step in the process, however, because itwould still be necessary to re-edge the flitchesbefore assembly in the glueup process.

Preparing Standard LumberThe rough, dry standard lumber was as-

signed randomly from the kiln to 23 sub-groups, with each subgroup having a totalsurface width of 36 to 48 in. The number ofsubgroups was reduced by random selectionto 20 for statistical comparison with EGAR

lumber. Each piece was measured to the near-est 0.01 in. in width and surfaced to AmericanLumber Standard dimensions for dry-dressedsoftwood lumber. The lumber was then placedin a controlled atmosphere to attain an EMC of12 pct until it was graded, measured for warp,and tested mechanically.

Preparing EGAR LumberAfter drying, the EGAR flitches were

edged on a straight-line rip saw using acarbide-tipped, smooth-cutting saw. Care wasused to place the rip line kerf in the wane sothat the widest possible square-edged flitchresulted. The edge surface produced by thesmooth-cutting saw was judged good enoughfor strong glue joints so no further surfacingwas done.

Panels were glued up by assemblingflitches at random as they came from the pile.Width of each flitch was measured to the near-est 0.1 in. and enough flitches were accumu-lated to make a panel at least 36 in. but notover 48 in. wide. By this procedure, the panelsbecame the equivalent of a standard lumbersubgroup for use in the analysis. Twenty-twopanels were assembled, of which 20 were

3

Figure 4.--Standard lumber and unedgedEGAR flitches piled for kiln drying. EGARflitches occupied 60 pct more space thanedged lumber.

(M 141 141-5)

selected by random method to match the 20standard lumber subgroups.

The adhesive was spread by hand using apaint roller, and no special effort was made tocontrol or determine spread rate. The assem-bly time was a minimum of 20 minutes and wasmeasured from the time the first surface wasspread until pressure was applied to the layup.Overhead screw clamps and heavy timbers ap-plied vertical pressure to keep the panels asflat as possible. Horizontal pressure was ap-plied by inserting a section of fire hose be-tween a side pressure bar that ran the fulllength of the edge of the panel (fig. 5). An aircompressor with automatic pressure controlsupplied air through fittings to the fire hose atbetween 105 and 125 lb/in.2 This systemproved satisfactory and resulted in relativelyflat panels and good glue joints. The adhesivewas a commercially available room-tempera-ture-curing phenol resorcinol and was permit-ted to cure for 20 to 24 hours (h) at tempera-tures of 70° to 85° F.

After assembly, the panels were stored atroom temperature. Lumber ripping lines werelaid off by using blocks that were cut to exact

widths of standard softwood dimension pluskerf of the rip saw (fig. 6). Blocks were matchedfor length at the ends of the panels, and stringswere stretched tightly between kerf notches atthe ends of the blocks. The position of thestrings established the position of the sawlinesthat divided the panels into standard-widthsoftwood dimension lumber. The criteria usedto position the sawlines were to minimizevisually the effect of defects in bending as ajoist, and to obtain as nearly as possible thesame number and mix of pieces of lumber thatwere obtained by the standard process.

Although it was unnecessary to plane theedges, the lumber was planed on both widefaces to the standard softwood dimensionlumber thickness of 1-1/2 in. Table I shows thenumber of pieces of dimension lumber the 20panels yielded and the number of gluelines.

After machining, the EGAR lumber wasstored under conditions to maintain an EMC of12 pct.

Glue Bond QualityThe quality of the bonds developed in the

EGAR lumber was evaluated with a slightly

4

Figure 5.--Assembly of dry and edged EGARflitches in glue press. Fire hose at left sideof panel applied 100 to 125 lb/in.2 of airpressure. Overhead clamps restrainedtendency to buckle.

(M 144 852-7)

Table 1.–Finished 8-ft EGAR lumber from 20 panels

5

Figure 6.--Edge-glued panel marked for rip-ping to standard softwood dimensionwidths of four 4-in., two 6-in., one 10-in.and a recyclable strip 1-1/2-in. wide.

(M 141 703)

modified version of ASTM D-905.4 Normallythe test specimen would be cut so that theshear area under test is 2 in. across the grainand 1-1/2 in. along the grain. However, the bestthat could be done in this instance with EGARmaterial was a specimen 1-1/2 in. across thegrain and 2 in. along the grain. This slightmodification is expected to yield slightlyhigher shear stresses than the standard shearblock results, but there should be no effect onwood failure.

The material for evaluation was obtainedby selecting at random 15 pieces containinggluelines, with at least 1 in. of wood on eitherside of the glueline. The 1-1/2-in. strip with theglueline centrally located was ripped fromeach piece. Rough blocks were then crosscutfrom this strip--one near each end, one at thecenter of the length, and two more at the thirdpoints. In a few cases, these positions had to bechanged slightly to avoid knots and local graindeviations. A total of five blocks were thus cutfrom each strip. The blocks were then notchedto fit the test apparatus and stored at 80° F and65 percent relative humidity (RH) until tested.The moisture content of the wood at the time oftesting was approximately 12 pct.

The block shear specimens were tested tofailure. The maximum load attained and theestimated percentage wood failure were re-corded for each specimen.

Mechanical PropertiesMechanical properties examined to permit

comparison between EGAR and standardlumber were limited to modulus of rupture andmodulus of elasticity. Additional properties ofthe lumber measured included: weight, dimen-sions, and estimated visual grading bendingstrength ratio.

In addition to visual grading, other non-destructive techniques for grading EGARlumber ‘may become of interest. One ismachine stress grading (MSR) which usesstatic bending modulus of elasticity as thenormal standard for quality control. Thereforemodulus of elasticity measurements usingdifferent techniques of current interest weremade to estimate static bending modulus ofelasticity (ESB). These included two dynamicmeasurements: Flexural vibration flatwise(EDB) and impact stress waves lengthwise(ESW) as defined previously.5

4 American Society for Testing and Materials. 1949.Strength properties of adhesives in shear by com-pression loading. ASTM D 905-49.

5 Gerhards. C. C. 1975. Stress wave speed and MOE ofsweetgum ranging from 150 to 15 percent MC. For.Prod. J. 25(4) :51-57.

Bending strength ratio (SR) was deter-mined by the displacement method of ASTM D245.6 Modulus of rupture was measured in astatic bending test according to ASTM D 198.7In the static bending test, specimens wereloaded edgewise at the third-points on an84-in. support span. Because the wider widthswould likely have failed in shear, only the 2 by4’s and 2 by 6’s were statically tested. Each2 by 4 or 2 by 6 was randomly oriented so thatthe “worst edge” had an equal chance of beingstressed in tension or compression. The 2 by6’s were also laterally supported during thestatic test.

ESB was determined in conjunction withthe static bending tests of 2 by 4’s and 2 by 6’s.EDB and ESW were determined on all widths.

After the 2 by 4 and 2 by 6 specimens weretested in bending, a 1-in. thick wafer, free ofknots and pitch, was cut from a point near thefailure area to determine moisture content(MC).

6 American Society for Testing and Materials. 1974.Standard methods for establishing structural gradesand related allowable properties for visually gradedlumber. ASTM D 245-70.7 American Society for Testing and Materials. 1974.Standard methods of static tests of timbers and struc-tural sizes. ASTM D 196-67.

RESULTS AND DISCUSSION

Yield of Green DimensionThe green flitches from the 20 subgroups

yielded 35 pieces of 2 by 4, 26 pieces of 2 by 6,23 pieces of 2 by 8, 20 pieces of 2 by 10, and sixpieces of 2 by 12, for a total of 110 pieces ofstandard lumber.

Yield of Finished LumberThe yield in dry finished lumber, plus 22 in.

of usable edge strips that could be recycled inadditional panels by the EGAR system, was 89pct of the total green flitch width. The yield ofdry finished lumber by the standard systemwas 81 pct of the total green flitch width.

Starting with the same width of greenflitches, EGAR produced 10 pct more footageof finished dimension lumber than the stand-ard system. An analysis of variance indicatedthat this difference in yield was significant atthe 5 pct level. Even without recycling the 22 in.of edge strips, the advantage for EGAR is a 7pct greater yield. If wider lumber were a spe-cialty, fewer sawcuts would be made in the

EGAR panels and the advantage would beslightly higher.

By the EGAR system, shrinkage duringdrying accounted for most of the differencebetween total green flitch width and totallumber width. Total loss from ripping, includ-ing saw kerf and strips too narrow to recycle,was just under 2 pct of the total panel widthbefore ripping. Edging to eliminate wane onEGAR flitches and standard lumber sometimesresulted in less than the measured widthbetween bark lines, particularly when unedgedflitches had some crook. This accounted for anadditional small reduction in yield.

In retrospect, when determining the flitchwidth, it would have been better to have usedlong straightedges to lay out edging sawlinesof the green flitches. Since both EGAR andstandard flitches were treated in the same way,no bias was introduced influencing the yield byone system more than the other.

The yield of finished lumber for both theEGAR and standard systems is shown intable 2.

Lumber GradeThe lumber was graded by an inspector of

the Timber Products Inspection and TestingService, Inc.8

The percentage of pieces falling into eachgrade is shown in table 3. An analysis of vari-ance of the grade yield indicated that the ap-parent superiority of EGAR lumber was notstatistically significant at the 5 pct level. TheEGAR lumber, however, graded 92 pct No. 1 orbetter compared to 86 pct for the standardlumber. Also, there was more EGAR lumber inthe Select Structural grade.

When the EGAR panels were marked forripping, location of defects was one criterionfor placing riplines to reduce the effect of knotson grade. In addition, approximately the samenumber of pieces by width were intentionallyproduced from EGAR panels as were pro-duced by the standard method. If the decisionscould have been made without limitation onnumber of pieces by width, probably the over-all grade average for lumber produced by theEGAR process could have been raised.

A higher proportion of 8-, 10-, and 12-in.widths would permit larger knots to be ac-cepted under the knot size rules, thereby im-proving the grade. It is possible in practice,

8 Timber Products Inspection and Testing Service,Inc., Eastern Division, P.O. Box 456. Lithonia, Ga.30056.

7

Table 2.--Summary of yield of finished lumber from 20 subgroups of standard andEGAR systems

System Total widthYield of dry lumber

Green flitches Dry finished compared to greenlumber 1 flitch widths

In. In. Pct

Standard 850.8 686.5 80.7EGAR 850.1 756.9 89.0

1 EGAR includes usable strips and losses due to edging mistakes.

Table 3.--Percentage of total number of pieces by widths, systems, and SPIB grades

however, that market demand for certainwidths might influence the ripping pattern and

(table 4). However, an analysis of variance

in some instances might result in a lower gradeindicated that differences were not significant

yield than the theoretical maximum.at the 5 pct level. It had been anticipated that,because the EGAR lumber was first dried,

WarpEGAR lumber had less warp than standard

lumber in most sizes and warp categories

edged, assembled into panels, and then rip-ped, it would be freer from warp than lumbermade by the standard system (edged whilegreen, dried, and planed).

8

Table 4.--Comparison of warp in 8-ft lumber producedby Standard and EGAR systems

Warp Board Width

Bow

Crook

Twist

In.

All pieces

All pieces

All pieces

Glue Joint Bonding QualityOf the 15 gluelines tested, 13 met the re-

quirements of ASTM D-25599 10(table 5). Onthis basis, gluelines 5-4 and 6-4 failed to meetthe minimum average shear strength require-ment, and 5-4 also failed to meet the minimumaverage wood failure requirement.

Both of these joints were examples ofwhat appeared to be a primary problem in theprocess used. The problem arose because asthe flitches dried, some cupped. When thecupped flitches were edged with the straight-line ripsaw, the cut was not always at rightangles to the faces, nor were the edges paral-lel to each other. As a result, when the flitcheswere laid up into panels and pressure appliedto them, the bonding surfaces did not fit prop-erly and wedge-shaped gluelines were formed.Such thick and thin gluelines are generallyweaker than a properly formed joint. The jointsin 5-4 and 6-4 were observed to be of the wedgetype.

Average warp (per piece in1/32-in. increments)

Standard EGAR

It is probable that the flitches can beripped to minimize the thick and thin gluelines.Then edge gluing of the flitches into panelsshould present no technical gluing problems.

Although no attempts were made to meas-ure durability, no problems are anticipatedbecause of the type of adhesive used and thegenerally high strength and wood failure re-sults obtained.

Mechanical PropertiesThe average static mechanical properties

of the EGAR lumber sample were significantlyhigher than those for the standard lumber

9 At 12 pct moisture content for southern pine, anaverage shear strength of 1,310 Ibs/in.2 and 75 pctaverage wood failure is required.1 0American Society for Testing and Materials. Stand-ard specification for adhesives for structural lami-nated wood products for use under exterior (wet use)exposure conditions. ASTM D-2559.

9

Table 5.--Summary of results of block sheartests1 on gluelines in EGARmaterial

Board No. Unit stress

Lb/in.2

1-0 1,3602-4 1,4803-0 1,4204-4 1,4505-4 4806-4 1,2607-4 1,6808-3 1,580

10-3 1,60012-3 1,36013-2 1,42014-2 1,69015-2 1,66018-1 1,40020-1 1,540

Wood failure

Pct

787692766182998395899788947889

1 Each value in the table is the average of 5 block sheartests.

sample in the 2 by 4 size but not in the 2 by 6size (tables 6 and 7). With the data from bothsizes combined, modulus of rupture averaged14 pct higher for the EGAR lumber than for thestandard lumber; strength ratio was 8 pcthigher and static modulus of elasticity 5 pcthigher.

Based on covariance analysis, strengthratio and modulus of elasticity differencesaccount for most of the modulus of rupturedifference between the EGAR and the stand-ard lumber specimens. In the covarianceanalysis with strength ratio and modulus ofelasticity as covariates, common slope andcommon intercept hypotheses pertaining toregressions through the four sets of data(standard 2 by 4’s, standard 2 by 6’s, EGAR2 by 4’s, and EGAR 2 by 6’s) could not be re-jected at the 1 percent level of significance.The common regression for the four sets ofdata with modulus of rupture in 1,000 Ibs/in.2 ,modulus of elasticity in million Ibs/in.2 , andstrength ratio in pct is

Table 6.--Average properties of EGAR and standard lumber 2 by 4 and 2 by 6 specimens

Lumbertype

Pct

Standard

EGAR

Standard

EGAR

Standard

EGAR

Size

2 by 4

2 by 4

2 by 6

2 by 6

2 by 4and

2 by 6

2 by 4and

2 by 6

Number ofspecimens

41 10.3 33.1 1.75 72 7.64

39 10.9 36.0 1.97 86 9.90

31 10.3 35.6 1.89 84 9.33

31 10.7 35.6 1.81 80 9.12

72 10.3 34.3 1.81 77 8.37

70 10.8 35.8 1.90 83 9.55

Moisturecontent

Pct Lb/ft3

Density

Averages

Staticmodulus ofelasticity

MillionIb / i n .2

Bending Modulusstrength of

ratio rupture

1,000lb/in.2

10

Table 7.--Pooled variances, t-values, and degrees of freedom for testingsignificant differences between EGAR and standardlumber specimen properties1

Lumber size Pooled Pooled variance (above) anddegrees student’s t (below) for

of comparing differences infreedom Static Bending Modulus

modulus of strength ofelasticity ratio rupture

2 by 4 78 0.15990 38.264 12.4172.460** 3.200*** 2.867***

2 by 6 60 .17642 30.162 11.821.750 .907 .240

2 by 4 and 2 by 6 138 .16708 34.741 12.158’1.302 1.904 2.002*

1 Significance levels of t-values--*5 pct, **2 pct, and ***1 pct.

Coefficient of determination (R2 ) was 0.71 andstandard error of estimate was 1.94. For com-parison, R2 for the simple regressions of MORon ESB and MOR on SR were 0.62 and 0.44,respectively.

Besides implying that the difference inmodulus of rupture between EGAR and stand-ard lumber specimens could largely be ex-plained by strength ratio and modulus of elas-ticity differences, the common regression alsoimplies comparable strength for comparablestrength ratio or modulus of elasticity valuesregardless of lumber processing type. A fur-thur implication is that EGAR lumber strengthpotentially can be optimized in the EGARprocess by optimizing, as noted previously, onstrength ratio--a function of knot size andlocation.

Dynamic methods of determining modu-lus of elasticity yielded results somewhatdifferent than the static method (table 8), with

lower values by the flatwise dynamic method(EDB) and higher values by the stress-wavemethod (ESW). Regardless of absolute differ-ences, correlation was good among the threetypes of moduli of elasticity, suggesting themachine stress rating potential of the dynamicmethods.

Eitner type of dynamic modulus of elastic-ity in conjunction with bending strength ratioyielded multiple regressions with bendingstrength as good as the multiple regressioncontaining the static modulus of elasticity.Multiple regressions were

with units as before. R2 values were 0.74 and0.72 and standard errors of estimate were 1.84and 1.90, respectively.

11

Table 8.--Comparison of modulus of elasticity measurement methods for EGARand standard (SS) lumber specimens1

CONCLUSIONS

(1 ) The sys tem fo r manu fac tu r ingsouthern yellow pine dimension lumber by theEdge-Glue-and-Rip system is entirely feasibleusing current technology and equipment.

(2) Analysis of variance for the twosystems--standard and EGAR--for board-footyield indicated a statistically significant in-crease in overall yield of 10 percent for theEGAR system. Both warp and grade showed anumerical superiority in favor of EGAR, but inneither case was the difference statisticallysignificant.

(3) If the flitches can be edged to givesurfaces that fit together properly, edge-gluing8/4 southern pine into panels for the EGARsystem will present no problem.

(4) Some of the EGAR lumber had higherstatic bending properties than the standardlumber. The higher bending strength of theEGAR lumber, however, was mostly attributedto higher bending strength ratios (a lumberquality characteristic that can be controlled byselective ripping of EGAR panels) and highermoduli of elasticity.

12 4 . 5 - 1 3 - 6 - 7 7