Veneer production trials were done at a commercial southern pine plywood plant to elucidate the effects of silvicultural treatments on veneer quality, yield, and modulus of elasticity. Forty-nine trees, totaling 1,3 11 ft³ (37 m³), were selected from an intensively managed, 50-year-old loblolly pine (Pinus taeda L.) plantation at the Hill Farm Research Station of Louisiana State University at Homer, LA. Trees were selected from each of four treatments, pre-commercially thinned (T) [average dbh 19.3 in (490 mm)], pruned (P) [average dbh 9.1 in (485 mm)], thinned & pruned (TP) [average dbh 19.2 in (488 mm)l, and control (C) [no thinning or pruning, average dbh 15.6 in (396 mm)]. Twelve trees were selected per treatment, except for the TP treatment which had thirteen trees. Each tree was felled, bucked into a log 17-foot-long (5.2m-long) plus trim, transported to the plywood plant, bucked into two 101.5-inch-long (2.6-m-long) peeler blocks (butt and upper), rotary peeled into 1/8-inch-thick (3.2-mm-thick) veneer using the plant's normal production process, then dried in a veneer drier. The length and width of full-sized veneer sheets [53-inch x 101.5-inch green and 51-inch x 101.5-inch dry (1.35 m x 2.6 m green and 1.30 m x 2.6 m dry)], full-length random width strips (including half sheets) and half-length fishtails and strips were recorded to establish veneer yields.

The facility produces veneer for a laminated veneer lumber (LVL) plant and for a commodity plywood sheathing plant. The plywood production facility manufactures 245,000 ft² (22,761 m² per 8-hour shift on a 3/8-inch (9.5 mm) basis. The LVL plant requires sorting the veneers by their modulus of elasticity values (MOE), which is done by a Metriguard Model 2600 FX veneer tester. The plywood plant requires visual grading for separation of core and face veneer as well as face veneer classification. Accordingly, the full-size sheets were visually graded according to U.S. Product Standard PS 1-83 in the green condition and after drying to establish veneer quality and drier degrades [A, B, C, D, and U (Utility) grades were identified] and by Metriguard for MOE determination.

The correlation of veneer stiffness and LVL, performance is constantly monitored by testing LVL, samples and adjusting the acceptable ranges of veneer ultrasonic sound transmission rates. Five classifications (G1, G2, G3, G4, and G5) are available, although only veneer in the G I through G3 groupings are actually used to produce LVL. These three categories correspond to the following Metriguard grade, millisecond range, and MOE values: GI, 0-435 ms, 2.44x10⁶ psi (16,823 MPa); G2, 436-475 ms, 2.17x10⁶ psi (14,962 MPa); and G3, 476-525 ms, 1.86x10⁶ psi (12,824 MPa). The G4 and G5 classifications are grouped together as below grade (BG) for the purposes of this presentation.

Compared to the control treatment, the T, P, and TP treatments slightly improved average MOE in veneers produced from the butt logs. The average Metriguard grade for the P and PT treatments was G2, while the average grade for the T and C treatments was G3. Top (upper) logs also showed a similar relationship for average MOE among the treatments, but the average Metriguard grade (G2) did not differ. The relationship of MOE to visual grade was less well defined.