Gluability of Southern Pine Earlywood and Latewood

Glue-bond quality, as tested wet and dry in tension, was best with earlywood to earlywood and poorest with latewood to latewood; earlywood to latewood was intermediate. Optimum closed assembly, time for latewood to latewood was zero minutes, while the optimum for earlywood to earlywood was 15 minutes. Latewood to latewood bonds showed a sharp increase in percentage of delamination (after exterior exposure) with increase in assembly time; the range tested was zero to 120 minutes. Earlywood cells in the vicinity of the glue line were compressed and impregnated with resin. The dense, thick-walled latewood showed no such cell deformation, and resin impregnation was confined to the cells immediately adjacent to the glue line. At any given percentage of wood failure, the bond strength was proportional to wood density.

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