Effect of High-Temperature Drying on Bending Strength of Yellow-Poplar 2 By 4’S

Four different sawing and drying combinations were used to process yellow-poplar logs into 2 by 4’s: conventional sawing with either conventional kiln-drying or with high-temperature drying and flitch sawing with either conventional kiln-drying and ripping or with high-temperature drying and ripping. Based on bending strength tests of 809 processed 2 by 4’s, an analysis of covariance showed that strength of high-temperature-processed lumber was only negligibly lower than and not significantly different from that for lumber processed by conventional sawing and drying. The analysis used accounted for effects due to differences between sample trees, whether tree pith was present in the 2 by 4, and the grade of the 2 by 4 based on knots and slope of grain–all significant factors. These results are based on yellow-poplar of high visual quality. Two other results of the study should be of interest to wood engineers and scientists. Strength was highly correlated with modulus of elasticity, suggesting possible machine grading application; 2 by 4’s containing the tree pith were not as strong or stiff as those without the pith, although visual grade characteristics were not appreciably different.

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