A method for optimizing lumber sorting before kiln-drying

Drying lumber can be quite challenging when uniformity and consistency are required. Over-drying and under-drying are common causes for lower grade recovery and dimensional stability problems. It is known that both over-drying and under-drying can be reduced by sorting green lumber into different moisture content groups. Additionally, sorting also offers the opportunity to redesign drying schedules. In this study, a new methodology was designed and tested to optimize kiln-drying of lumber by implementing green sorting coupled with modified drying schedules. The methodology was applied to optimize the drying of 114 by 114 mm(2) hem-fir lumber sorted with an NMI capacitance type meter. It was found that in comparison to unsorted lumber, sorting into three groups reduced the drying time by approximately 7 percent and recovered around three-quarters of the under-dried lumber.