Conventional kiln drying and equalization of Western hemlock ( Tsuga heterophylla (Raf.)[Sarg]) to Japanese equilibrium moisture content

Abstract

Density sorted, matched-samples of Western hemlock were dried in order to quantify the physical changes of conventionally kiln dried wood when exposed to the equilibrium moisture contents of a typical Japanese winter. Physical changes were monitored for 14 weeks by sampling board weight, dimensions, shell and core moisture contents (oven-dry basis) and warp. The difference of 7% in equilibrium moisture content between Tokyo and Vancouver is large enough to elicit a response in shell moisture content, dimensions and warp. However, the responses found should be expected when wood is examined in context of its natural variability. Drying 105 mm by 105 mm Western hemlock to 19% moisture content at the core should be considered the maximum target moisture content. A target moisture content of 15% at the core would balance drying time and end-use stability as the lumber is equalized to Japanese conditions.