Dynamic Transverse Compression Treatment to Improve Drying Behavior of Yellow Birch

In an effort to improve the drying characteristics of yellow birch lumber, an investigation was conducted to evaluate the effectiveness of a dynamic transverse compression treatment prior to kiln-drying. Clear green heartwood boards were compressed between steel rollers to pre-set deformation levels ranging between 2.5 and 12.5 percent of the green thickness, and were subsequently dried using a high-temperature (215?F) kiln schedule. Best results were obtained at the 7 and 8.5 percent deformation levels where only minor degrade developed in comparison to total degrade in matched nontreated controls. Wood subjected to 8.5 percent deformation was examined further to assess the effect of the compression treatment on wood properties. Measurements of radial moisture movement indicated that the average moisture conductivity coefficient had been increased by about 21 percent, a microscopic examination of the wood showed that numerous splits had developed in the vessel pit membranes. Tests of basic strength properties showed slight reductions in modulus of elasticity, maximum bending stress, and maximum transverse tensile strength but all were statistically non-significant.

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