Veneer cutting and drying properties

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Title:
Veneer cutting and drying properties
Physical Description:
Mixed Material
Creator:
Forest Products Laboratory (U.S.)
Publisher:
USDA, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29294992
oclc - 226379415
System ID:
AA00020541:00001

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.. .. FORCES! PRODUCTS I.ABORArTORY t FORFI-SI spk\ i 1
-| -.- I U. 5. DEPARTMENT O- ACRI( UI.TI'Ri.

VENEER CUTTING AND DRYING PROPERTIES


ENGELMANN 5PRUCE


Engelmann spruce (Picea engelmanni) grows at high elevations in the
mountain ranges of the western United States and Canada 1 Its wood is
soft and light in weight, closely resembling the wood of the eastern spruces
in appearance and properties The heartwood is nearly white The sap-
wood is narrow and only slightly lighter in color than the heartwood The
wood has a fine texture; the growth rings are fairly distinct It is straight-
grained and has moderately low shrinkage The wood is likely to contain
many small sound knots because of the many small, persistent lirnbs


Selection and Preparation of Logs for Cutting -


The veneer cutting and drying properties of Engelmann spruce were e4Tured---
by the Forest Products Laboratory and the Northern Rocky Mountain Forest
and Range Experiment Station. Logs for the tests were selected on the
St. Joe National Forest, in the vicinity of Roundtop, about 15 miles south of
Avery, Idaho. They came from a well stocked stand of virgin white pine and
spruce, with a scattering of white fir, Douglas-fir, and larch The trees in
this area were generally from 250 to 300 years old and 25 to 30 inches in
diameter at breast height. The selected logs represented the best available,
of a type that would be considered for veneer cutting The average clear
length available from each tree generally did not exceed one 16-foot log. The
field data are summarized in table 1.

The logs were cut to 8-foot bolts, all but two of which were cut into veneer
in a commercial plant. Two 8-foot bolts (from trees 13 and 14) were pro-
cessed at the Forest Products Laboratory in 4-foot lengths. Some of the
commercially cut bolts were heated in water at 160 F or at 1400 F for 60
hours. Others were cut without heat treatment. Of the four bolts cut at the
Laboratory, two were cut without heat treatment, one was heated for 48 hours
in water at 120* F and one was heated for a similar period at 170" F Heat-
ing in water was effective in loosening the bark sufficiently so that it could be
1
.Betts, H. S. Engelmann Spruce. Amer Woods Ser Forest Serv U S.
Dept Agr. 1945.
2
-The Underwood Veneer Co. Wausau. Wis cooperated in this study



Report No. 1766-10 September 1953
I Maintained at Madison 5, Wisconsin in cooperation with the University of Wisconsin
Agriculture Madison







removed readily with hand tools. However, such heating was found to
be unnecessary for purposes of good cutting, and even knotty material
could be cut, unheated, without damage to the lathe knife.


Veneer Cutting


Most of the wood was cut satisfactorily on the rotary lathe. Some sap-
wood veneer of the heated bolts was fuzzy because of overheating. The
smoothest veneer was cut from unheated bolts, and with the proper lathe
adjustment this veneer was also relatively free from severe lathe checks.
Most of the veneer cut commercially was 1/16 inch thick, but a small
quantity was 1/6 inch thick At the Laboratory 1/16- and 1/8-inch veneer
was cut, The lathe settings! used to cut this veneer are given in table 2.


Veneer Drying


Most of the veneer was dried flat and free of splits in mechanical driers
of the roller-conveyor type A small amount of light compression-wood
was observed in some of the wood, and veneer containing this material
split and buckled in drying The average moisture content of the heartwood
was 37 percent before drying, and that of the sapwood was 140 percent. The
wood was dried to an average moisture content of 2 to 5 percent. The width-
wise shrinkage during drying was about 7 percent. The drying schedules
used are given in table 3


Veneer Quality and Yields


Only a very small volume of clear veneer was produced from the spruce
logs In practically every bolt knots were encountered within the first few
revolutions on the lathe, regardless of how smooth the logs were on the out-
side The knots were small, averaging less than 1 inch in diameter. How-
ever, they appeared to be too numerous for patching and many of them fell
out during drying, particularly in the 1/16-inch veneer In sliced veneer, it
is reported, only very few knots fall out during drying.


3
-Fleischer, H 0 Experiments in Rotary Veneer Cutting. Proceedings,
Forest Prod Res Soc 1949.


Report No. 1766-10


-2-






The average diameter inside bark of the logs cut was 22 inches The
commercially cut logs, in 8-foot length:, were peeled to a diameter of
about 7 inches From a total log scale of 3, 700 board feet a gross
volume of 4, 958 board feet of green veneer was cut T'Ihe net volumre of
green veneer after clipping wjs 2, 850 board feet The large reduction
was due to the removal of areas containing excessively large numbers of
knots. Only 200 board feet, or about 7 percent of the veneer, was free
of knots and considered suitable for clear face or crossband veneer

The wood of Engelmann spruce, like that of the other spruces, is consid-
ered easy to glue, that is, satisfactory bonds can be produced over a
comparatively wide range of gluing conditions and no unusual precautions
in controlling gluing operations are needed Gluing techniques that are
satisfactory for such species as white fir, western hemlock, and eastern
white pine are considered satisfactory for Engelmann spruce No gluing
difficulties were encountered in making a small number of sample plywood
panels from the veneer that was cut experimentally

Potential users of Engelmann spruce, who examined the clear veneer as
a possible substitute for basswood as a crossband material, considered
it unsuitable for this purpose because it contained too pronounced a grain
pattern In competition with other softwood species that are currently
being used for crossbands, however, the material, if clear, should qualify
for this purpose.

The bulk of the veneer, containing many small knots, would probably be
useful mainly for the production of plywood for sheathing and container
uses It is thought to be particularly adaptable for some types of containers
because of its light weight, its fine light color, and its freedom from odor
and taste.


4
Commercial Experience-


Some Engelmann spruce veneer is being sliced on a commercial scale to
provide faces for a decorative type of knotty paneling Cants are selected
at the saw, having a good scattering of small red knots. They are steamed
for 48 hours in kilns at 140 F

The veneer is sliced 1/12 inch thick. It is reported that some difficulty
occurs in cutting because of slivers that tear from the flitch at the end of
each stroke.

4Information supplied by Potlatch Forests, Inc, Lewiston. Ido
-Information supplied by Potlatch Forests, Inc. Lewiston, Idaho


Report No. 1766-10


-3-




- m


It is reported that the veneer is readily dried without defects and
presents no gluing problems. It is, however, more difficult to edge
joint than is pine, and some splitting and checking may be evident
around knots. A good yield of knotty face grade of veneer is obtained.
Veneer not suitable for faces is used in a utility back grade.


Report No. 1766-10


-4-





I a


Table 1. --Field data on material


selected for test


Tree
No.








13





14




15





16





17


Total : Age
height : at :
:stnyrp


Lo Length
Ng) 1


Feet :Years


Diameter:
at breast
height



Inches



32





27




31





31


300+13-1
:13-2
:13-3



305 14-1
:14-2



260 :15-1
15-2


Feet



16 :
16
16 :


156





128




125





135





123


Diameter
inside
bark
small erd

Inches



24
23
22



23
21



22
21


23
21
19



22
20


Net scale
(Scribner
Dec C)



Board
feet

400
380
330
1,110

380
300
680

360
300


66 0


380
300
240
920

330
280
610


Visible
defects
in tiirk


Clear
Clear
3 knots



Clear
Clear



Clear
Small knot
near top



Clear
Clear
3 knots



Clear
Clear


-Log No


1 was the first log above the stump


Report No. 1766-10


240 :16-1 -
:16-2
:16-3


276 17-1
:17-2








Table 2.--Lathe settings used to cut Engelmann
spruce veneer


Veneer
thickness


Inch


1/16


1/8


: Knife angle


Degrees -Minutes


90 00


89 30


: Nosebar openings
;---- -----------.-------------
: Vertical : Horizontal
n c
* -- ---- -- -- In---- --:-----
: Inch : Inch


0.016


. 026


: 0.050


: .105


Table 3. -Drying


schedule used for Engelmann spruce veneer


Type of Type of
drying wood





Laboratory: Heart


Do ... . do . .


Do. ... do .


D o ... .. do.....


Commer- Heart and
cial : sap


Do.. : ..... do .. .


Thickne



Inch


1/16


1/16


1/8


1/8


1/16



1/6


ss Temperature
in dryer


F.


250


325


250


325


250



270


Time in


Time in
dryer


Minutes


8 -10


5-8


13 15


10 12


19



41


Report No. 1766-10


Cal C
Z
w rn


CO 0
- *-n
a>-n
40 - x
--- m= 0


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