17/ FOREM PRODU' ORATORY t FOREST SERVICE GRICULTURE VENEER CUTTING AND DRYING PROPERTIES >NE Pacific madrone (Arbutus mcnziesii Pur sh ) is a moderate -sized hard- wood tree found in the Pacific coastal country from British Columbia to southern California. In California it also grows in the western Sierra Mountains below 4, 000 feet elevation. The tree is also known as madro: and madrona. It is locally used for fuel wood, fence posts, charcoal, and to a minor extent for lumber and veneer. The latter uses are limited because of the tendency of the tree to grow with poor form except in dense stands. The tree attains a diameter of 2 to 4 feet (3_)J_ and a height of about 80 feet on good sites (7). The wood is heavy, fine textured, and shows little distinction between early and late wood. The heartwood is generally reddish brown and the sapwood yellow white in color (1). The "figure" in the wood is due largely to pigment color differences in the heartwood. The wood works easily with tools but it was noted in this study that it had a tendency to chip rather than splinter. It is intermediate in strength 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 pub- lished by the Forest Products Laboratory (8_). Description of Logs Tested I / *«».., I / Two 4-foot-long madrone bolts were received at~Th~eHF«*£^i^F?Qattcts labo- ratory from Sonoma County, California for rotary veneer cuttiiigte"sT5\ £. They were reported to be of average or better quality for madrone from that area. They were without exterior defects except for small end checks. These bolts were numbered 3 and 5. Two logs were also received for slicing tests. d. These were butt logs and were fairly round with the pith approximately in the geometric center. The —Underlined numbers in parentheses refer to literature cited at the end of this paper. _The logs were selected by the California Forest and Range Experiment Station, Berkeley, Calif. _The logs were furnished by the Simpson Logging Company in cooperation with the California Forest and Range Experiment Station. Report No. 1766-14 April 1959 i Maintained at Madison 5, Wisconsin in cooperation with the University of Wisconsin 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 Cutt ing 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 conditioning 8 -foot madrone bolts in water at 180° F. to insure a temperature of 140° F. at a core diameter of 6-inches is as follows: Log diameter Heating time (InT) (Hrs.) 12 8 24 36 36 98 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 Heating time (In.) (Hrs.) 6 4 12 15 1 8 40 Report No. 1766-14 -2- 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 veneer. 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 themselves cut smoothly and easily. The knots 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 3- The smaller logs, Nos. 3 and 5, had many splits after heating, which reduced the recovery of face veneer. Gluability 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. Finishing 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 -4- Literature Cited Brown, H. P. , Panshin, A. J. , and Forsaith, C. C. 1949. Textbook of Wood Technology, Vol. I, first ed, Book Company, Inc. , New York. McGraw-Hill Fleischer, H. O. 1949. Experiments in Rotary Veneer Cutting. Society Proceedings, Vol. 3, pp. 137-155. Forest Products Research 3. Harlow, William M. and Harrar, Ellwood S. 1941. Textbook of Dendrology. Seconded., 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- nia. 6. Schowalter, W. E. 1946. Exploratory Tests in the Rotary Cutting of Veneer from Certain California Hardwoods. Forest Products Laboratory Progress Report WP-66. 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, O. W. 1956. Kiln-Drying Schedules for 1 -Inch Laurel, Madrone, Tanoak, and Chinquapin. Forest Products Laboratory Report No. 1684. Report No. 1766-14 -5- 1.2-7 DO CD -P » O -p -p O 1 p •H > CD > -P O (D cd P p bO P cd cd hD CD Ph ft 0) O t> -H w TJ -P < O 0) Ph P Ph cd CD co CO Ph oj| -p 'S -P P o P > CD -P •p O P p p bO O cd CD cd o a) Ph P W (U t> P id -P «: p o P -p o CD CO > O •H Ph P o cd CD a W Ph t>s -P •H CD O bfl -H S3 ^! • qn -P P CD P o •H M > Ph < O O CD CD ti bo,P O cd -p O • P Td f*H > P CD *H o Ph M t> > cd < CO si g o 3 P S cd •H cd CO CD M < -H ,o 73 bO • o o ^ ^ ON o O -4" 3 OJ o OJ CVJ C— -^- VO H H OJ OJ O OJ OJ OJ H i to H On 00 H VO H OJ LPv On -=f H H -=f -=f OJ 3 VO -4- to I -H- K\ t— OJ rO IT\ OJ OJ OJ OJ H CO -p o CD

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