Effect of Temperature, Time, and Drying Medium on the Strength and Gluability of Douglas-Fir and Southern Pine Veneer

The effect of three treatments on strength properties of veneer was investigated by static bending tests to determine modulus of rupture (MOR) and modulus of elasticity (MOE). The treatment effects on gluing veneer into plywood were investigated by evaluating shear strength and percentage of wood failure. The temperatures selected were 350?,600?, and 800? F, and drying was accomplished in a medium of air and superheated steam. Two drying times at each temperature and drying medium were selected to study the effects of time. Drying times did not affect the values for MOR and MOE; longer drying time had some effect on gluability of Douglas-fir veneer but not on southern pine veneer. Drying in steam increased the values in MOR and MOE of each species an average of 7 percent. Drying in steam did not affect the gluing properties of Douglas-fir veneer, but shear. strength for the southern pine veneer was increased by 12 percent. Although temperatures caused differences in the strength and gluing properties of each species, no patterns were established, since the means of the properties studied did not increase or decrease as drying temperature increased, except for isolated instances. This study has illustrated that temperatures up to 800? F may be used for a limited time to heat and dry the veneer.

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