The Influence of Production Variables on Quality of Southern Pine Plywood

Laboratory plywood panels, 3/8 inch by 1 foot by 1 foot, were made using a variety of conditions and a standard phenolic adhesive consisting of 25.3 percent resin solids and 58.4 percent water by, weight. Panels were subjected to vacuum pressure shear and wood failure estimation. Production conditions lowering percent wood failure were high temperature of 105?F., low humidity of 34 percent, open assembly time, panel pressure below 200 psi, and high moisture veneers (7-9 percent) at 5 minutes assembly time and low moisture veneers (1-3 percent) at 30 minutes assembly time. Conditions where less effect upon percent wood failure was measured were high humidity, veneer age, and optimum conditions of moisture (4-5 percent) and 15 minutes assembly time. The greater rate of water adsorption of southern pine compared to Douglas-fir was measured. The effect of glue temperature (no relation) and veneer thickness (negative correlation) upon glue spread was also measured.

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