Potential Sources of Variation That Influence the Final Moisture Content of Kiln-Dried Hardwood Lumber‪.‬

Abstract Excessive variability in the final moisture content (MC) of hardwood lumber may have a significant impact on secondary wood processing and final product performance. Sources of final MC variation during kiln-drying have been studied in prior research. A test examining the final MC of red oak (Quercus spp.) and yellow-poplar (Liriodendron tulipifera) lumber after kiln-drying was conducted to obtain empirical knowledge of the effects from anatomical structures and lumber thickness. A [2.sup.3] fixed-effects linear statistical model was used to examine MC changes and the effects that growth rate, thickness, and wood type have on MC variability of red oak and yellow-poplar 4/4 lumber during the kiln-drying process. Growth rate was comprised of "fast" and "slow" levels. Lumber thickness had "thin" and "thick" levels, and wood type had heartwood and sapwood levels. The entire experiment was duplicated to improve the inference of experimental results. Variability in the MC of red oak lumber steadily increased during kiln-drying before the equalizing treatment, and was significantly reduced after equalization. This empirical study may suggest that the equalization treatment is an important step in the kiln-drying of red oak lumber. Variability in the MC of yellow-poplar declined during the entire kiln-drying process. There was statistical evidence in the duplicate experiments that suggested that the wood type (heartwood or sapwood) had a significant effect on red oak final MC. There was no statistical evidence to suggest that the three factors studied had an effect-on the final MC of yellow-poplar lumber.