Effect of water storage and methanol extraction on longitudinal gas permeability of Karamatsu heartwood

The purpose of this study was to clarify the effect of extractives on longitudinal gas permeability. Karamatsu (Larix leptolepis Gord.) heartwood was used in the study. The specific permeability, K, in heartwood is discussed in relation to the treatments of water storage and methanol extraction. The results are summarized as follows ; It was found that water storage before natural-drying affected low-permeable specimens (Fig. 2). It was found that the specific permeabilitiy, K, of heartwood naturally dried after water storage, was related to the cross-sectional area of latewood in specimens (Fig. 4). Methanol extraction increased the specific permeability, K, of heartwood (Fig. 5). There was a positive correlation between the increase of permeability and methanol extractives (Fig. 6). Microscopic observations showed that the increase of heartwood permeability by methanol extraction was caused by the solution of some incrusted heartwood materials on pit membranes and by the removal of resin in resin canals (Fig. 7).