Veneer cutting and drying properties

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Material Information

Title:
Veneer cutting and drying properties ponderosa pine
Series Title:
Rept. ;
Portion of title:
Ponderosa pine
Physical Description:
4, 4 p. : ; 27 cm.
Language:
English
Creator:
Forest Products Laboratory (U.S.)
University of Wisconsin
Publisher:
U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory
Place of Publication:
Madison, Wis
Publication Date:

Subjects

Subjects / Keywords:
Veneers and veneering   ( lcsh )
Lumber -- Drying   ( lcsh )
Ponderosa pine   ( lcsh )
Genre:
bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 4).
General Note:
Caption title.
General Note:
"July 1956."
General Note:
"In cooperation with the University of Wisconsin."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029646882
oclc - 759166211
System ID:
AA00020833:00001

Full Text
p -/ FORE51 PRODUCTS LABORATORY t FOREST S5.RVI( .
~' U. S. DEPARTMENT OF ACRI(UITIIRK

-------- VENEER CUTTING AND DRYING PROPERTIES



it "PONDEROSA PINE



Ponde'rosa pine, Plrfus' ponderosa, is one of the most widely distributed and
important of the western timber trees. It grows in every State west of the
Great Plains, and in British Columbia and northern Mexico (3). -

The wood of ponderosa pine varies widely in quality. The outer portions of
old-growth trees are often soft, slow grown, and uniform in texture. Second-
growthtrees andthe inner portions of old-growth trees may be knotty, resin-
ous, comparatively hard, and their summerwood is markedly denser than
their springwood. The sapwood, which generally is 2 to 4 inches thick, is
white to pale yellow, and the heartwood is light reddish brown. The wood is
moderately light in weight and generally straight grained. Occasional trees
have spiral grain.

High-grade ponderosa pine lumber is used principally for doors, sash, frames,
paneling, and molding, while the lower grades are used for boxes, sheathing,
joists, and rafters. Rotary-cut ponderosa pine veneer is made into plywood
for such uses as kitchen cabinets. Sliced knotty ponderosa pine is made into
plywood for use as paneling.


Selection and Handling of Logs

Veneer cutting tests were made on five different lots of logs obtained from
various locations. Four of the shipments consisted of old-growth timber and
the fifth of tree tops of second-growth timber. These logs are described in
table 1.

Uniformly slow growth is preferred to fast growth in veneer logs. Some of
the defects observed in test logs, which should be avoided whenever possible,
were decay, blue stain, large knots, and pitch streaks. Ponderosa pine is
very susceptible to blue stain, and should be cut into veneer as soon as pos-
sible after the tree is felled. If this is not possible, the logs should be stored
under water.

1
-Underlined numbers in parentheses refer to Literature Cited at the end of
the text.


Rept. No. 1766-12 July 1956


Maintained at Madison 5, Wisconsin in cooperation with the University of Wisconsin
Agriculture Madison







Preparation of Logs for Cutting


Ponderosa pine canbe rotary cut or sliced at room temperature (2, 6). Lab-
oratory tests showed that tighter and smoother veneer can be produced from
logs and flitches that have been heated at 140 F. This is particularly true
.,.'hen 1/8- or 1/4-inch-thick veneer is cut.

Ponderosa pine veneer logs or flitches conditioned in water at 140 F. should
be heated for the periods shown in table 2.


Lathe and Slicer Settings

Settings (4) that were satisfactory for cutting veneer of various thicknesses
are given in table 3.


Veneer Drying

As shown in table 1, the moisture content is about four times as great in
ponderosa pine sapwood as in the heartwood. Because of this difference in
moisture content, the sapwood veneer requires a longer drying period than
the heartwood. Schedules for drying the veneer in a progressive, roller-
conveyor dryer are shown in table 4.

Some of the sheet ends of the rotary-cut sapwood veneer wrinkled during dry-
i g. In further tests, wrinkling was prevented by overlapping the ends of the
veneer sheets 1/4-inch as they were fed intothe dryer (5). The sliced veneer
dried f-it exceptfor some buckling around knot clusters. Some of the larger
knots split daring drying. In one specification, knotty western white pine
flitches are limitedto a knot size of 1 inch (1). It wouldbe desirable to limit
the knot size in ponderosa pine flitches. A maximum diameter of 2 inches
would probably be acceptable from the technical standpoint of cutting and dry-
ing the veneer.


Veneer Yields

When compared with the Scribner Decimal C log rule, both the rotary-cut
and the flat-sliced veneer generally showed an overrun in laboratory tests.
The yield of quarter-sliced veneer was about that indicated by the log scale.
Veneer yields obtained under factory operating conditions, however, usually
fall far short of those obtained in laboratory tests.


Rept. No. 1766-12


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The yield of veneer from individual logs varied greatly. The lovs from
Mexico yielded 34 percent clear veneer; those from Libby, Montana, 71
percent clear veneer; those from Flagstaff, Arizona, 20 percent clear veneer;
the h, from Lincoln County, Montana, 55 per (cent clear veneer; and the tree
tops from California, 100 percent knotty veneer.



Plywood

Laboratory tests and commercial experience show that ponderosa pine can
be glued with protein and resin glues by the cold-press and the hot-press
methods. Other tests have shown that ponderosa pine is in the group of woods
that glue well with different glues under a moderately wide range of gluing
conditions (7).

Pitch that is sometimes encountered in ponderosa pine heartwood may cause
plugging of the finishing belt. It is reported that this may be overcome by
using a more open-coated paper than is used for Douglas-fir (2).

Most ponderosa pine plywood is made for interior use (8). The light color
and even texture of old-growth ponderosa pine make it well suited for uses
such as cabinets. Knotty material makes attractive paneling when it is flat-
sliced.


Rept. No. 1766-12


-3-


1.2-8








Literature Cited


(1) Anderson, I. V.
1948. Specifications for Knotty Western White Pine Veneer Flitches.
N. Rocky Mt. For. & Range Exp. Sta. Research Note No.
68.

(z) ____________
1954. Suitability of Rocky Mountain Woods for Veneer and Plywood.
Journal of Forestry 52(8): 587-591.

(3) Betts, H. S.
1945. Ponderosa Pine. American Wood Series. Forest Service,
U. S. Department of Agriculture.

\4) Fleischer, H. 0.
1949. Experiments in Rotary Veneer Cutting. For. Prod. Res.
Soc. Proc. p. 137

(5) Lutz, J. F.
1955. Causes and Control of End Waviness During Drying of Veneer.
Forest Products Journal. 5(2): 114.

(6) Reinmuth, P.
1950. The Manufacture of Pine Veneer. For. Prod. Res. Soc.
Proc. p. 332-338.

(7) U. S. Department of Agriculture
1955. Wood Handbook. Agriculture Handbook No. 72, p. 234.

(8) U. S. Department of Commerce
1949. Ponderosa Pine and Sugar Pine Plywood. Commercial
Standard CS 157-49.


Rept. No. 1766-12


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Table 1.--EaccriLtf n of ..r.: j


Source of
logs


: : : : : : : l: 2" :'
..;uEter : Log :Diameter,: 1-InLa :Aver :rt- r.,- -Moisture content-:'.-''' -.: .:',ernal : -ects
:of log3:length: small : per :sapwood:tricity: ------------- :r:. ::.-. -rance :encoutered
: : : ,.niJ : inch : width :of the:- woo,:Heartwood: : i : i. .-
: : : : : : pith : : : : : cut :


Chihauhua,
Mexico


Kootenai
National Forest
Libby, Montana



I -," It Itrf,
Arizona






Lincoln County,
Montana



Yubia (ounty,
Cali I'ornia


4






2







1




5 :


Feet Inches

16 15-20








52 19-52






8 : 18-25







52 :




8 : 11-15


Inches

5-44: 4








9-55 5-6





5-40 :1-1/2-

: 5






10-57 : 5




'-12 5


:Inches :Pzrcent: F

5/4- :128-142:
:1-1/2







0-5 : 156






0-1 :114-145:







1 I. '




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


percentt

54-43 : 0.58- :P -:gbt Knots t --
: 0.44 :and clear. to "-inch
:1:.-i-o: stain diameter .
: and pin- : itch
S:holes in :streak in
:the sap- :one ..
: ~ W :wod.

352 :.59-.44 :Clear old- :C .:.-. ion
S:growth :wood in one
: : :.:;:. l.rge
:: :knots near
the core

28-50 :.o -45:.'r.-l,.rl-:Blue stain
indicate' : :in 3 -. -
: knots .e- :- ts
cay in saa-:'" -*...:ut
: wood and :the 1 .. .
: :heartwood :'.Sn ..y.

'" :.*4- 'lear old-:Y .'" clear
: :growth o *:Few knots nt

: : :.:aet er

....... ......... :notty sec-la- knotse,
: on i -- *^'hn 0iu1 stain,
: :tr e t :. : w ...4"
SBlu.e s- I
: :;ind worn :
: ~: .- ," -'e


I
-Baoed on weight


when ovendry.


I"d on volume when Vl *n I we ,'. when ovend-.







Table 2. --Heating schedules for ponderosa pine logs
and flitches in water vats


Average diameter-i

Inches


Vat temperature

0 F.


SHeating time-
* Hour-----------
: Hours


LOGS


140

140

140


FLITCHES


140

140

140


1
Average end dimension for flitches.
2
-If steam is used in place of water, the heating times
could be reduced 5 to 10 percent.


Rept. No. 1766-12







Table 3. --Knife st-Hiiigs. ftor ittiiig | (Iirt'Ir s A i inI-1 vreneer


Veneer
thickness


Inch


1
Knif e


Pressure bar


: Bevel : Angle : B vel : Vertical :Horizontal
: : opening : opening

SDegrees Degrees-: Degrevs : Inch : Inch


~: :Minutes :


LATHE


1/8 (0. 1250)

1/16( 0625)

1/ 20( .0500)


21 :

21 :

21 :


89 55

90 15:

90 30:


SLICER


1/4 ( 2500)

1/8 ( 1250)

1/16( .0625)


20 :

20 :

20 :


90 20:

90 20 :

90 30:


knife:
knife:


Rockwell hardness 58; hollow ground
Rockwell hardness 62; flat ground.


0. 002 inch.


Rept. No. 1766-12


15 :

15 :

15 :


0. 026 :

014 :

014


0. 110

050

040


12 :

12 :

12 :


1
-Lathe
Slicer


.035

.035 :

.030 :


. 240

S115

S055




UNIVERSITY OF FLORIDA

3 1262 09216 3004

Table 4. --Schedules for drying ponderosa pine veneer


Veneer
thickness


:Sapwood or : Temperature :Time in :Final moisture content
: heartwood : in dryer : dryer ---------------------


: : Average : Range

Inch : : *F. :Minutes : Percent : Percent

1/4 :Sapwood 315 : 27 : 8 : 5- 14
:Heartwood 315 19 : 6 : 4-9

1/8 :Sapwood 315 15 : 3 2 4
:Heartwood : 315 : 11 2 1-1/2 3

1/16 :Sapwood 255 9 : 5 4 8
:Heartwood : 255 5 : 7 : 4-9


Rept. No. 1766-12