REDUCTION O? WASTE IN THIE VENER AND PLYWOOD IiDUSTRY
By H-ERBERT 0. FiEISCH3R, Technologist
Forest Products Laboratory,-1 Forest Service
U. S. Department of Agriculture--
The Occurrence of Waste -- .*-uj- -:Y
All stages in the conversion of wood from the standing tree to the final
veneer or plywood product are accompanied by incidental waste in some form
or other. This report deals with that portion of the waste that occurs at
veneer and plywood plants. Waste occurring in the woods is discussed in
another Forest Products Laboratory report.-
Contrary to popular opinion, the waste that occurs in converting a log into
veneer is considerable. In a study conducted by the Forest Products
Laboratory- it was found that the average yield of veneer from a yellow birch
log is only about 47 percent of the cubic volume of the log. The conversion
of veneer into plywood entails additional wastes that probably average about
50 percent in the typical hardwood plywood plant, so that the yield in terms
of veneer actually made into plywood often is as low as 20 to 25 percent of
the log volume.
In the Douglas-fir plywood industry the relative volume of waste is lower
because larger logs are involved and the plywood product is such that a large
percentage of the veneer produced can be used in panels. The yield in terms
of plywood is considered average if the square footage of the 3/8-inch plywood
obtained equals 2 to 2-1/2 times the board-foot volume of the log. On the
basis of a log with an average diameter of 40 inches, this yield amounts to
about 55 to 68 percent of the cubic-foot volume of the log. These yield
figures do not lend themselves to direct compar'-i W-ih Fv gures
because the finished plywood product is genera y 6|gJftj01?gfa ty as
to be ready for final application without much trvmytw S ez often
requires a great deal of trimming, resurfacing, and the like by the co tumer.
Also, plywood goes further because it is gener ly usentr Ii f. she ts
than lumber for similar applications.
1A U-A& nVi. of Frori-'3
-Maintained at Madison 5, !,is., in cooperation with tTm T"g"T
-l"Woods Waste," FPL Report No. R1666-3.
-"Waste in Veneer Manufacture," FPL Resort No. R1493.
Report No. R1666-4
";aste carn occur in many ways. In its most obvious form it consists of log
-nds, veneer and plywood scraps and trimmings, cores, reject panels, and the
like, that often find their way to the scrap box. Sometimes it exists in the
form of a low-grade product that might have been a high-grade product were it
not degraded because of improper cutting, handling, drying, gluing, and other
improper operations. Sometimes it exists in the form of brash veneer, com-
pression wood, or other naturally occurring defects that result in an
Some forms of waste in the primary operation are unavoidable, such as veneer
rousidinEs and triumin6;s and veneer cores, but these wastes can often be re-
duced by refinin6 the production operation. Other forms of waste can be
eliminated entirely or reduced considerably within the limits of economy.
Finally, the reduction of waste can be brought about by salvaging what aight
be considered waste in the primary operation and utilizing it for some
Reduction of "aste in the Primary Operation
The first and most important step in a waste-reduction program is to adopt
measures that will prevent the occurrence or reduce the volume of material
that is normally considered waste. The operator should therefore analyze
each step in the production process with this in mind. The following dis-
cussion presents examples of how other operators have attacked this problem.
The selection of logs by grades suited to the product to be cut from them is
an important step in reducing waste. Many high-grade logs are "butchered"
into low-grade veneer under conditions that do not justify the practice. On
the other hand, the cutting of low-grade logs in an operation geared to the
production of high-grade veneer may mean a financial loss to the operator.
The veneer operator who is cutting woods-run logs into veneer would do well
to give some thought to costs, yields, and the selection of logs to suit his
particular operation. He should examine the possible outlets for logs not
handled to best advantage in this plant.
Unwarranted waste 'eight occur in logs that had been stored in a yard
improperly or for too long a time. End checking and rot occurring under
these conditions are preventable either by providing underwater storage for
logs, or by using end coatings to prevent checking4 and chemicals to prevent
stain and decay,_
A certain amount of loss may result from the handling of logs with cant hooks,
pike poles, and axes: Time taken to train men handling logs and peeling bark
to wield their tools carefully so as to avoid damage to the outer portions of
Forest Products Laboratory Report No. R1435.
Forest Products Laboratory Technical Note No. 225.
Report "o, R1666-4
logs, from which the highest quality veneer is normally cut, will certainly
pay for itself in the reduction of waste. When bucking the logs into bolts,
due attention should be given to taper, sweep, knots, and other defects, so
that the veneer produced will be of the highest grade possible. In a study
conducted by the Forest Products Laboratory6 the importance of sweep on the
final veneer yield, both in quantity and in quality, was analyzed. It was
found that sweep was one of the more important controllable factors affecting
yields; its effect can be minimized by carefully selecting logs so as to
provide the long bolts required from the straight logs and cutting the logs
having excessive sweep into short bolts, Greater care should be used in the
woods to eliminate excessive sweep by proper bucking practices. Bolts should
not be so long that an excessive amount of veneer will be lost in the form of
end trimmings or in the spurring operation.
The heat-conditioning of veneer bolts for cutting is a process that requires
careful control to prevent excessive waste in the form of degrade. Over-
heating of some species results in excessive end checking of the bolts ad in
poorly cut veneer. Underheating may result in loose veneer that is not suit-
able for a high-grade product. The practice of heating various species of
wood and logs of different diameters together, on the same schedule and
possibly in the same tank, will sometimes result in some avoidable degrade
because of improper temperatures for some of the species and dialieters. The
practice of heating wood in log ln6th instead of bolt length, as is commonly
done in Europe and occasionally in this country, is one that can be used to
reduce the amount of split veneer obtained because of end checks in the bolts.
The part of the lathe operator in reducing waste in veneer and plywood manu-
facture is a most important one. His technique in handling the lathe deter-
mines to a large extent the use for which the veneer is suitable. Improper
lathe settings may result in veneer that is too loose, too rough, or too
variable in thickness to be used for high-quality products. The condition of
the lathe -- whether it is in proper working order or whether it is worn and
subject to vibration --. and the condition of the knife and nose bar are all
In rotary cutting, a reduction in core diameter is often thought of as being
a desirable method of reducing waste. It is not so important, however, as
it might at first appear. To cut to core diameters smaller than the conven-
tional diameter requires the addition of special lathes having small spindles
and the rehandling of partially cut bolts, and in addition wood cut from the
central portions of logs is generally of low quality. Consequently, cutting
the cores to small .diameters has not usually been found economically feasible.
Where long lathes are used so that it is not practical to cut to a 6-inch
core because of the deflection of the bolt in the lathe, some operators have
nevertheless installed a shorter, lighter lathe, cut the long cores in half,
and turned them down to smaller diameters on the small lathe.
-J. Harry Rich, "Effects of sweep in the `bolt on rotary cut veneer yields,"
Report No. R1666-4
A certain amount of avoidable waste occurs in the handling of green veneer
from the lathe to the clipper. In large operations where it is possible to
handle the green veneer mechanically through automatic clippers the utiliza-
tion is at its best, for tears in the veneer do not commonly occur and single
sheets are clipped to best advantage so as to eliminate defects. The minimum
,,idth of veneer clipped by present-day automatic clippers is 2 inches. This
minimum m results in a certain amount of waste, since many defects could be
eliminated by clipping out only a 1-inch width. In smaller operations where
expensive automatic conveying and clipping equipment is not justified, the
veneer is often torn into sheets and then clipped to standard widths in
multiple. This results in a certain amount of waste at each tear, in the
introduction of additional splits because of manual handling, and in sheets
that are not clipped to best advantage from the standpoint of eliminating
defects. A method of winding the green veneer on reels directly from the
lathe, which is now use-d to some extent in hardwood plants, is one that
can be used in smaller plants to reduce veneer waste. Clipping sheets singly
to random widths so as to eliminate defects, even if manual handling is
necessary, is a practice that will reduce waste because it results in a
higher percentage of high quality veneer.
A practice tnat is doubly wasteful is the clipping of veneer from spiral-
grained or interlocked-grained woods without regard for grain direction.
When veneer of such woods is torn at the lathe into sheets for handling and
then clipped pe-pendicular to the ends, large.triang-alar sections are
inevitably clipped at each tear and are wasted. FurtherLore, the grain
direction of the clipped sheets is not perpendicular to the edges and plywood
made from such veneer usually warps. If, on the other hand, the veneer is
clipped along the grain direction and then squared by trimming at the ends,
the quality of the veneer is improved and the amount of waste incurred in
producing it is reduced, especially if the veneer is clipped to fairly narrow
;ieces. When green veneer is handled on reels, it is easy to provide for
setting; the rnel at an an-le to the clipper knife so that veneer cut from
s-iral-grained bolts is clipped parallel to the grain.
The process of drying veneer sometimes results in waste because of degrade
that occ,'u's in the form of splitting, honeycombing (in thick veneers), and
buckling (especially at ends). Whne-n veneer is dried in a kiln, special pre-
cnutions should be taken to ile it so that it is free to shrink during
drying. If this is not done many of the veneer sheets may split. In all
typos of v.nccr driers it is necessary to use drying schedules adapted to the
type of veneer being dried so as to avoid degrade during drying. The storage
of dry veneer, its subsequent handling, and its redryring may result in
:urthcr losses, many of which can be reduced. It is sometimes desirable to
store veneer and veneered products in hu.idity-controlled rooms to prevent
d.vclopment of defects related to dimensional changes that occur with changes
in humidity. The adequate control of humidity in plants and in storage sheds
is not difficult.7
Forest Products Labor-atory Reports Nos. P1140 and R1612.
nc)port :0. R1666-4
Much opportunity for the reduction of waste exists also in making plywood.
Good gluing practice is necessary to produce good plywood and to reduce to
a minimum the number of reject panels.- Much of the warping that causes
rejection of plywood panels can be eliminated by careful control of veneer
quality and gluing conditions.2 In the production of diagonal-grained
panels and panels having matched-face veneers, there is necessarily a great
deal of waste in cutting the veneer to size. Waste-reduction practices in
this case would require the utilization of narrow widths and small pieces of
veneers. When clipping veneers to size for matching, it is desirable, from
the standpoint of waste reduction, to clip in small piles instead of large
piles, so that the veneer can be arranged to best advantage. Waste occur-
ring in clipping a large portion of a single flitch to uniform width can
occasionally amount to one-third of the volume of the veneer being handled.
By clipping this same veneer in two piles instead of one, this volume of
waste veneer could be reduced to one-half that occurring before, or to one-
sixth of the total volume of veneer.
The Reduction of Waste Through Secondary
Utilization Within the Plant
The universally accepted method of utilizing veneer and plywood waste is for
fuel. This method has the advantage that all wastes, bark, veneer, cores,
and plywood, green and dry, can be used.-- In many cases the use of wastes
for this purpose may be justified, but most operators are, nevertheless,
constantly casting about for more profitable outlets,
A reduction in veneer waste is often made possible by the application of a
certain amount of ingnuity and the introduction of new machinery. In one
plywood plant a reduction in the proportion of veneer that normally went to
fire the boiler was brought about by construction of a machine, called a
"veneer retrieve," for rapidly cutting to size smaller pieces of veneer.
The veneer passes rapidly on a conveyor through this machine, in which a
12-foot clipper knife cuts it to width. A series of undercut saws at 1-foot
intervals, under push-button control, cuts the veneer to lengths determined
by the operator. Veneer pieces down to 24 by 4 inches in size are salvaged
in this way, and the machine is said to salvage a quantity of veneer per
8-hour shift equivalent to 5,000 board feet (log scale).
The introduction of various types of edge splicers, such as one incorporating
a large heated drum about 5 feet in diameter about which the veneer passes
and from which it emerges as a continuous sheet made up of edge-glued pieces,
has made it possible to produce economically core and cross-banded veneer
-USDA Bulletin No. 1500, "The gluing of wood."
-Forest Products Laboratory Report No. R1252.
10Forest Products Laboratory Report No. R1666-13.
Report No. R1666-4
sheets from a large number of narrow widths. Other types of edge-jointing
and splicing equipment are available for rapidly and continuously edge-
splicing veneers of various thicknesses and grades.
Patci.ing equipment is available for cutting out knots and other defects in
veneer or on .lywood faces and for replacing them with patches. Cracks in
face plies can be patcned with shims. Plastic-wood compounds are being used
in some instances to fill defects in plywood faces and for plugging core
skips appearing on plywood edges. Plywood panels having large defects that
cannot be patched, are generally cut back to a smaller standard size.
In many instances it is possible to reduce waste in a plant by increasing the
number and widening the variety of products produced in the plant. A plant
makingg bushel baskets r:.ay produce a large number of "shorts." or pieces of
veneer not large enough for the standard bushel. If, however, 1/2 bushel
baskets or other containers of a smaller measure are also made, many of the
shorts can be used profitably. The theory of diversification of products, of
which this is a very simple example, and the theory of integrating the wood-
utilization practices of several ty-pes of plants, as between a sawmill, a
veneer plant, and a pulp or a chemical conversion plant, should be considered
by ever:, operator who has any volume of waste wood on his hands.
During recent years the use of paper and paper plastics as surfacing mate-
rials for veneer and plywood has been developed and affords a metnod of using
waste veneers. One panel product is made by edge splicing many narrow strips
of defective veneer, that are normally clipped out as waste, and bonding a
heavy kraft paper to each panel surface. Th.e product is used for shipping
containers, luggage, toys, cabinet backs, and the like. Another similar
product is r..ade by gluing waste veneer strips together with faces parallel to
each other to form a two-ply laminate, but overlapping each other so that a
continuous wood panel is obtained, and by bonding resin-treated paper to each
surface to add stiffness and to cover the defects. Operations of this kind
are generally set up on a large scale and require a continuous large supply
of waste pieces to maintain operation.
A ver: common method of using veneer cores in the vc-neer plant is to saw them
into crating lumber for use by the plant itself. In the southern container
industry cores obtain-d from cutting basket and container veneer are often
sawed into lumber for use as head sticks and hamper bottoms. Special small
circular or sash gang saws for rapidly cutting veneer cores arc obtainable
and are commonly used for this purpose. In the southern container industry
it is also common to cut yellow pine and hardwood cores into excelsior.
Sale of "'astc
Under favorable market conditions it is possible to dispose of large
quantities of veneer cores (and sometimes trimmings) for use in the manufac-
ture of wood flour, mechanical fiber for boards, roofing felt, and the like,
Report No. ?R16E6-4 -6-
and for use in pulp production, in distillation and extraction, in charcoal
production, and as fuel.I.I
The sale of veneer cores for sawing into lumber is not uncommon. A small
West Coast sawAiill is currently buying the crntire output of cores from a
veneer plant and sawing then into dimension lumber. It is reported that the
daily output of the mill is 16,000 feet, 80 percent of which is in the form
of 2 by 4's 8 feet long.
Veneer cores can be used as rollers for moving houses, heavy machinery, and
the like, but this outlet is somewhat limited as to volume.
Cores of certain lengths can readily be used for fence posts, markers, and
the like, for which purposes their smoothness and general appearance is an
asset. Cores of larger diameters can be quartered for use as posts. Many
species of wood used for veneer, however, are not particularly durable
when in contact with the ground. Preservative treatment of the heartwood of
some species is very difficult. Buyer preference for woods of certain
species and the adherence to specifications on the part of large consumers,
that in many cases would rule out the use of cores because of cracks, knots,
and other defects, are other obstacles.
Veneer cores are sometimes used in the construction of log cabins, either in
the round or after sawing in half. In this case considerations concerning
the durability of the wood are not so important.
The use of veneer waste for the manufacture of containers, such as baskets
and berry boxes, is a good one. The container industry, however, is one that
requires specialized equipment and is generally built around its own veneer
supplies, since it is often cheaper to cut low-grade veneer for the purpose
than to try to handle veneer scraps from another plant. The container
industry is also somewhat localized at points where the containers are
required and, consequently, is not a suitable outlet for veneer waste from
Hardwood veneer waste is used, especially in the Northeast, in the production
of small novelties, such as cards, greenhouse and nursery labels, ice-cream
spoons, surgical splints, tongue depressors, candy sticks, and cocktail mixers.
Most of these items are stamped out. They are often made of white birch and
area byproduct of the toothpick industry. Other species, however, such as
yellow birch, hard maple, yellow-poplar, black tupelo, and sap sweetgum, also
possess the qualities desired in these products, namiely, light color, freedom
from taste and odor, ease of manufacture, and ease of polishing.
Plywood waste in the form of oanel, edgings is usually burned. One '-est Coast
firm, however, has equipped itPsas nner with two saw blades, instead of one
at each side, so that panel trimmings are equalized as to width. These trim-
mings are bundled and sold to woodworking plants that can use the narrow
stock in making small items or as trim or framing on larger items.
-lForest Products Laboratory Report Nos. R1666-6, R1666-9, R1666-10, R1666-11,
Report No4 R1666-4
Another possible use for plywood trimmings is the gluing of such trimmings
toEether flatwise so that the sawed surfaces are exposed and furnish a sur-
face that may be well-adapted for a use such as flooring. One West Coast
plant is exploring the possibility of using high-frequency equipment in a
machine designed for continuous production of flooring from plywood trim-
mings. The trimmings are to be set on edge, one behind the other, and fed
through the gluing machine continuously to cure the resin glue.
Panels rejected because of pressing difficulties or other serious defects
are often sold for uses whose requirements arc less exacting, such as crat-
iig. Reject portions of cut-back nanels can be made to serve a similar use.
Small segments of par.'.ls remaining after cutting out circles or irregular
shapes find their ;aost acceptable outlet among manufacturers of novelties,
toys, and small articles. They can also be glued together to furnish blocks
for turning into yulleys or other articles.
Limitations on the Use of WIaste
Once the decision has beer; made to undertake a program of waste reduction,
elimirnition, and utilization in a ;lant, the next consideration is the
economic factor. In many cases waste wood is u"ed as fuel, and as such it
has a real economic value in the rlant. The return to be obtained from
diverting was.e wood to other uses must, therefore, be sufficient to cover
at least the added cost of its rehandling and tne cost of fuel tnat must be
bought to replace it.
The various examples cited show what can be done to reduce or utilize wood
waste. Certain li.,itations should, however, be pointed out. Veneer cores
represent the least problem. Tney are easy to handle in the form of cord-
wood, a.-id handling and shipping them to considerable distances, as is now
done with pulpwood, is justified.
Veneer scraps, however, are not easy to handle. The majority of all waste
veneer is green, so that a large part of its weight is water, and it is
generally not in standard shapes and sizes that lend themselves to stacking
and handling. Because of its high moisture content, it is subject to rapid
deterioration because of stain and mold. The most practical place for Sand-
ling it is in the parent olant, or perhaps at a.i adjoining plant so located
that mechanical conveying is possible.
Plywood scraps may: be of various shares and sizes, or they may be somewhat
uniform in pattern and size. In the first case, they can ke used economically
only by, the operator who can afford to spend tine in sorting, handling, and
devising uses for small pieces. In the second case, the scraps can be
bundled, shipped some distance, a:.d handled on a production basis provided a
customer is found who has a quantity, use for the particular shapes and sizes
Report 1:o. R1666-4
I~ ~~. .....:: ......
&' 1.ai1i&ble. The species and grade of the plywood are an important considera-
': tion, It the grade is of high quality, considerable expense in handling is
: justified; if it is of low quality, the user might find it to his advantage
: to buy full-sized plywood sheets rather than to handle many small pieces.
I Uses for Waste Wood from Veneer and Plywood Plants
. Table 1 lists possible uses for waste wood from veneer and plywood plants in
Sa manner to permit individual analysis with respect to local conditions. It
contains the chief outlets that are known at present. It is subject to
revision as more information becomes available.
S Copies of the Forest Products Laboratory reports referred to in the table and
elsewhere may be had upon request to the Forest Products Laboratory,
Madison 5. Wig.
Report No. B1666-4
jI.,dERSi OF FLORIDA
3 1262 08924 3454lI III
3 1262 08924 3454
... ., .1~
T. bl l.--Use for maissaedoC fine wen end sinned plant
Us I yp of I Spol.I
---- ------------ I---a------------------
a- and $-ply
o e, hmdIstlickI.
and bapur bottom
Liot and cfUsenco
Iute. @takeu. and
oller, for moving
nd Ue likle
crueryl labels. ice-
auml Ikl-l Ii.c-
crow *pons, r.Lrcl-
cal splinti, tlongl
nlxeru. end the like
Toyr. novelties and
i 1ib-grude dSrd4oodi
iGore 6 lichsfiDeusr species are
i or more In z preferred
: e ror iMay
CGores :Mostly batch. birchk
.Cares mlassot. aspen. so
I I yellow pine. and
a I wood preferred
:Cores. veneer Maple, birch, dad a
iCoreu I pr n Man
:GPllore :Cho~iefly- Dogir f
I plywood, log I
I suds. sIaw,- I
i duit, ulabs. a
i Cores iMay
Cores :refsrobly durable
a 1 tritable
ISander duit imay
sCoreu Preferably hard mo
IVener "Chiefly white birch
a a Could probably use
l :maple. yellow birc
l ysllow-poplr. bli
tapelo. as sap
I 5 ueiOt
aFlywood lDaugla-fir (at pro
spot a large outlet. often probed ae a Nm vsu 11s hI SM g
SaO* IL Deport So. B1666-L .
zoaLmAser plymwood plan can soe low-MIrs weire feo this pin :e..
The colntainer Ilndustry a pecidtMalued Induutnr ilimI igllIiIni
I ia on veneer. Vensr. dry or pstlally "r, ld 1 iW ..
I thick, in various sle.s, am be nee :
:otaillly a large outlet. Se IL Deprt fD. lifiUs N "Pi
li Utlu i .,L:.
uthernmXxcheelor planti are often operated L commetiln with
ottoa-i operations. Dolt lugths of 18 liahes, frm of llt. M iW U i
spun aW d by iasufactJrera of roofnlag felt nd the llke. Vien r Wti "
I should be hogged. fre of dirt end bark Se i Dpart o. ,.,
iPnel gling. irlset to unifart iddU, are Lue together to .t .
i edg-grain flooring '
:Generally uad In parent plat. Sotimel sil local. be iL
i Dprt no. 11666-13
rally u d in parent plant. See NL eprt no. 666-4 O r
Material should be 8 feet lean or lger,. tire ontipat of ai .
I Doulas-fir sill going to a small ill located nearby. A ,
i present the lmber produced has an exell=t market. Us Ill i
D report to. B1666-8 "i
IUse of cores for posts varie with the loclilty. ITb aN -r "e'n!m
i quartered for mall posts .'i.
i :i .,IM:.1^!
iCoreu cam be used by pulp illl located at som disance. a m.ai iM **
i lis ms a for pulpwood. TVaer li belog amd by palp mIe lulem** ;.
very near to veneer will., but It met be hog00d to chipe@o afti Ift
I als. Se e Deport Do. u1666|
iDtor dust is omtimesli preferred to wood flair s a iller ae .a 91.
i plastic molding reiaIs '*.
Ia large market. Cores free of crack would be prefer:..
inser L/32-ianch or thicker, to be crashed so as to fold lat b.... "ni
- les quar es
: likely be sawd In two. There Is n established mua S t at Vpa.e
l * *
:Thobe I = are genrally produced t the parent vo er pleat :
I Veneer &crp@ c be used inL thicknsse of approxlitely 1/16-lmeh
iTrillion of hib-grhds paels are preferrad- Solin Lm eorlt
I bu olen through retailers of craftmem's ad ahbbyliet'i plle
SUnuelSoted plywood, but naifors in thickne. is glad ft Laia.
IThe plywood Is jewel-eut into 1-lach , asi i that the pafli
a Is flexible atOd can be glul to carved all erfoen i
sent) iPanl edglage. tried to vaifom width ar, d fr alrtw emol
PerorL ho. 1b66-
Z H 14092 P
i.Q. ,,X .