■10 FOREST PRODUCTS LABORATORY t FOREST SERVK i. U. S. DEPARTMENT OF A(,KI( ULTURE VENEER CUTTING AND DRYING PROPERTIES ENGELMANN SPRUCE Engelmann spruce (Picea engelmanni ) grows at high elevations in the mountain ranges of the western United States and Canada ]_ Its wood La 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 distirut 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 limbs Selection and Preparation of Logs for Cutting The veneer cutting and drying properties of Engelmann spruce were 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 1 6-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 140° 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 — 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 y 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 l/16-inch veneer In sliced veneer, it is reported, only very few knots fall out during drying. 3 —Fleischer, H O 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 IL inches The commercially cut logs, in 8 -foot lengths, were peeled to .1 diameter of about 7 inches From a total lug scale of 3,700 board feel a ^ross volume of 4, 9S8 board feet of green veneer was cut '1 he nel - olume of green veneer after clipping was Z, 8S0 board feet The large reduction was due to the removal of areas containing excessively large numbers of knots. Only ZOO 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 1/1Z 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 4 —Information supplied by Potlatch Forests, Inc , Lewiston, Idaho Report No 1766 10 -3- 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 Table 1 --Field data on material selected for t Tree : Diameter . Total Age - Lot; Length Diameter: Net scale- Visible No : at breast height at No ! inside 'S< nbner defe< ' height stunp l • ■ bark : small end- Dec C) in bark • Inches ! Feet Years Feet Inches Board feet 13 32 ■ 156 300 + 13-1 ! 16 24 400 Clear : : 13-2 : 16 23 380 Clear : : 13-3 • 16 22 330 3 knots 1 • 1,110 14 ■ 27 128 305 : 14-1 : 16 23 380 Clear :14-2 • 16 21 300 Clear • • 680 15 ! 31 125 260 ! 15-1 : 16 22 360 Clear -15-2 16 21 300 Small knot : : near top 660 16 : 31 : 135 ! 240 t 16-1 : 16 23 380 Clear .16-2 16 21 300 Clear 1 16-3 : 16 19 240 • 3 knots : ; 920 17 : 28 - 123 : 276 .17-1 : 16 22 330 Clear •17-2 - 16 20 280 : Clear : 610 —Log No 1 was the first log above the stump Report No 1766-10 Table 2. -- Lathe settings used to cut Engelmann spruce veneer Veneer thickness : Knife angle Nosebar op enings : Vertical : Horizontal Inch : Degrees -Minutes' Inch 0.016 . 026 Inch 1/16 1/8 90 - 00 : 89-30 : 0. 050 . 105 u> z — » ^^^^™ < m IN) en o aa^^— oo — ■■■-- CO O rv) ~' : ■n - — ^^— — •t- O tO =^= X OS =^^=z o = > Table 3. --Drying schedule used for Engelmann spruce veneer Type of : Type of Thickness Temperature : Time in drying : wood in dryer : dryer : : Inch : °F. : Minutes Laboratory: Heart 1/16 250 : 8-10 Do. . . .: ... do. .... : 1/16 : 325 : 5-8 Do. . . .: . . .do : 1/8 : 250 : 13-15 Do. . . .: ... do : 1/8 : 325 : 10-12 Commer- : Heart and : 1/16 : 250 : 19 cial : sap : Do. . . .:. 1/6 : 270 : 41 Report No. 1766-10