Veneer cutting and drying properties


Material Information

Veneer cutting and drying properties
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Forest Products Laboratory (U.S.)
USDA, Forest Service, Forest Products Laboratory ( Madison, Wis )
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aleph - 29295865
oclc - 226379560
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Full Text
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Pacific madrone (.A rbut i menziesii ;Iur i ) is a m rate-:sized hard-
wood tree found in the Pacific coastal country from British Columbia to
soutithern California i Caliiforni it aso gr ws in i he we ste rn Sierra
Mountains below 4,0 feet elex action. Tal tre i. al) known as madrono
and madrunci. It is locally used for Ijl wood, f c post s, ciircoal,
and to a minor extent for lumber and veneer. '.e latter uses arr limited
because of the tendency of the tree to grow with po ur xcet ik tense
stands. The tree attains a diametler of 2. lo 4 feet (3)_A and a hI ght of
about 80 feet on good sites (7). The wood is heavy, fin textured, and
shows little distinction between early and late wood. I he heartwood is
generally reddish brown and the sapwoor, yellow white in (color (1). The
"figure" in the wood is due largely to pigment color differences in the
hea rtwood.

The wood work,., easily with tools but it was noted in this study that it had
a tendency to chip rather than splinter. Ii is intermediate in stren-th be-
tween hard and soft maple (5). The lumber is difficult to dry, with warp
and collapse being major problems. Kiln-drying schedules have. been puib-
lished by the Forest Products Laboratory (8). .--

Description of Logs Tested I

Two 4-foot-long madrone bolts were received a t-(;2 I i-. _- "- rurl.:, t t '
0 -.. - __a__o -
ratory from Sonoma County, California for rotary v en, 1 i .I ;"t_.-
They were reported to be of average or better quality for madrone from
that area. They were without exterior defects except for s. all ecnd checks.
These bolts were numinbered 3 and 5.

Two logs were also receive for slici,-. tests.13 These were butt logs and
were fairly round with the pith .,,;roximnatcly in the geometric center. The

-Underlined numbers in parentheses refer to literature cited at the Cend of
this paper.
.The logs were selected by the C.',il ifornia Forest and P. 'ie Ex-- rimnent
Station, Berkeley, Calif.
3The logs were furnished by tit, Sirpson LOG. i Company in cooperation
with the California Forest and R, ,'e F, priment :.,.tion.

Report No. 1766-14 *-pril 1959

t Maintained at Madison 5, Wisconsin in cooperation with the University of V'* -..;.

logs were green when received at the Laboratory and in good condition except
for heart checks. These logs were numbered 223 and 224. A more complete
description of all test material is given in table 1.

Based on the test logs described in this report, the main defects to be avoided
in the selection of veneer logs are knots, bark pockets, and heart checks.

The moisture content and specific gravity values (table 1) were determined
from disks cut from the interior of the logs.

Preparation of Logs for Veneer Cutting

Eight flitches for quarter slicing and two flitches for flat slicing were sawn
from the two larger logs Nos. 223 and 224. Each of the flitches was about
6 feet in length. The smaller logs (6), Nos. 3 and 5, and a bolt from log No.
224 were used for rotary cutting. The bolts were about 4 feet in length.

Bolts 3 and 5 were heated in water at 210 F. before being cut into veneer.
Good quality veneer was produced but heart checks in the bolts opened up
excessively during heating. The 4-foot bolt from log No. 224 was heated at
160 F. The heart checks already present opened up only slightly with heat-
ing. Smooth tight veneer was produced from this bolt.

The flitches were heated at 180 F. Defects due to heating did not appear in
the flitches or in the veneer. Good quality veneer was sliced from the flitches.

The approximate heating times required for
in water at 180 F. to insure a temperature
6-inches is as follows:

Log diameter


conditioning 8-foot madrone bolts
of 140 F. at a core diameter of

Heating time


The approximate heating times required for conditioning 8-foot flitches in
water at 180 F. to insure a temperature of 160 F. at the flitch center is
as follows:

Average end dimension of flitch


Report No. 1766-14

Heating time



Veneer Cutting

The lathe and slicer settings given in table 2 were satisfactory for producing
veneer of good quality.

The veneer cut smoothly and was uniform in thickness. No defects other than
shallow knife checks were produced in the veneer during rotary cutting or
slicing. The uniform texture of the wood aided in the production of smooth

The rotary-cut veneer had many splits due to the heart checks in the bolts.
Much veneer was lost at the clipper in cutting out areas of included bark in
the outer 5 to 6 inches of diameter of the bolt cut from log No. 224. The
wavy grain caused a minor amount of figure in the sliced veneer.

Short grain around knots caused localized roughness in the veneer. The knots
themselves cut smoothly and easily.

Veneer Drying

The veneer was dried in a mechanical roller-conveyor type dryer. Drying
schedules are shown in table 3.

The ends of the sheets of rotary-cut veneer wrinkled badly in drying. Much
of this may have been due to the logs having become partially dried on the ex-
posed ends before cutting.

Splits in the rotary-cut veneer tended to widen and lengthen during drying.

Tangential shrinkage was high, during the drying of the veneer to a moisture
content of 3 to 8 percent, averaging about 13. 5 percent of the green dimen-
sions. Radial shrinkage averaged about 6. 5 percent of the green dimensions.

The drying results were similar at both temperatures used.

Veneer Yields

The good quality of the large logs, Nos. 223 and 224, resulted in the recovery
of a high proportion of face-grade veneer. Most veneer degrade was caused
by knots. Other causes of degrade were splits and bark pockets.

Report No. 1766-14


The smaller logs, Nos. 3 and 5, had many splits after heating, which reduced
the recovery of face veneer.


Five-ply panels were made with 1/28-inch madrone faces and backs and yellow-
poplar (Liriodendron tulipifera) cores and crossbands. A phenolic film glue
was used. Good plywood was made using a pressure of 150 pounds per square
inch, a temperature of 320 F., and a pressing time of 10 minutes. The glu-
ing of madrone with other adhesives is discussed in Forest Products Labo-
ratory Report No. 2030 (4), which states that madrone does not present un-
usual gluing problems and good joints can be expected with any of the con-
ventional woodworking glues with good control of gluing conditions.


The panels needed little sanding because of the smoothness of the madrone
face veneers. After sanding the panels were finished with a clear lacquer
to a uniform gloss.

Appearance and Uses of the Veneer

Madrone has good potentialities as a face veneer wood. Some of the veneer has
exceptional color variation in the heartwood. The heartwood of freshly cut
veneer may have a uniform light red color or it may vary in color from vari-
ous shades of red and brown to gray-green. Veneer and plywood exposed to
sunlight becomes a more uniform light brown. Plywood faced with rotary-cut
veneer may have a widely varying color. Quarter-sliced faces are somewhat
less striking due to the uniform grain on the radial surface. Panels faced
with flat-sliced veneer are intermediate, showing an attractive grain and
color pattern. Limited quantities of madrone veneer have been cut commer-
cially for face veneers for plywood paneling and for veneered furniture.

Report No. 1766-14


Literature Cited

1. Brown, H. P., Panshin, A. J. and Forsaith, C. C.
1949. Textbook of Wood Technology, Vol. I, first ed. McGraw-Hill
Book Company, Inc., New York.

2. Fleischer, H. 0.
1949. Experiments in Rotary Veneer Cutting. Forest Products Research
Society Proceedings, Vol. 3, pp. 137-155.

3. Harlow, William M. and Harrar, Ellwood S.
1941. Textbook of Dendrology. Second ed., McGraw-Hill Book Co. ,Inc.,
New York.

4. Olson, W. Z.
1955. Gluing Characteristics of Chinquapin, Tanoak, California Laurel,
Madrone. Forest Products Laboratory Report No. 2030.

5. Schniewind, Arno P.
1957. The Strength and Related Properties of Pacific Madrone. I. General
description and strength properties in the green condition. Paper No.
4. California Agricultural Experiment Station, University of Califor-

6. Schowalter, W. E.
1946. Exploratory Tests in the Rotary Cutting of Veneer from Certain
California Hardwoods. Forest Products Laboratory Progress Report

7. Tarrant, Robert F.
1958. Silivical Characteristics of Pacific Madrone.
Silvical Series No. 6. Pacific Northwest Forest and Range Experiment
Station. Forest Service, U. S. Department of Agriculture.

8. Torgeson, 0. W.
1956. Kiln-Drying Schedules for 1-Inch Laurel, Madrone, Tanoak, and
Chinquapin. Forest Products Laboratory Report No. 1684.

ReDort No. 1766-14 -5- 1.2-7

Table 1.--Description of test logs

Log: Average :Length: Total : Number of :Average: Average Average Average
No.:diameter: : number : rings per inch: width :eccentricity:moisture content2:specific gravity2-
: (inside: :of rings: --------------- of : of----------- --- -----
: bark at: : at :Maximum:Minimum:sapwood: pith :Sapwood:Heartwood:Sapwood:Heartwood
Small :midlength: : : :
: end) : : : : : : : :
___ -.. -...------- -- --- -: -: : : ------------ - ------- --- ...---
: In. Feet : : In. : In. :Percent: Percent :Percent: Percen
In. :Feet : : In. : In. :Percent: Percent :Percent: Percent

4 :......... ...... : /4

4 ......... ....... ....... 1/2

12 : 192 : 18 : 15 : 1

12 : 145 : 16 9 :1-1/2





**....... : ...... S....S..........
* *. S ** *.. . .

142 : 124 : 0.45: 0.49

167 : 124 : .50 .52

-General description: Logs 5 and 5, no defects visible, heart checks on both ends; log 225, no defects
visible under bark, burl at diameter of 18-inches,heart check; log 224., no defects visible under
bark, heart check at butt end, ring shake at 4-inch diameter.
-Based on ovendry weight.
-Based on green volume and ovendry weight.









,'ublf 2 .-- ,1 i 1. '' .

Me:t.ld : Veneer :
l: : thickness :

!'rii:'e : No-- b. r tt,- -. :
bevel : ...... .

cutting, : : : : : rizontal
veneer : : : :
-- ----c------- r,----.--- -- --- -- ------ ------------
Inches P !Lrijr ?:ii'i. D T n c I fl-iCh B







9C- 20









: Vertical :

: Inches : ".

Oy. I")



Table 3.--Veneer drying schedules used and
madrone veneer

shrinkage values determined for

Veneer Veneer dryer Dryin.- time- Aver&- shrink,.-., values2
thickness temperature ---- ------------
::: Radial : 7--n --ential

In. C F. Min. : Percent : Percent






: 6.7 :

* .
* boIo, ...oi



After drying the moisture content ranged from 35 to 8 percent, based on ovendry
weight; the sapwood had 1 to 2 percent hit;-her moisture content than the heart-
-Based on green dimensions.

Report No. 1766-14

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