Abstract
1 The longer the duration of heat-treatment at high temperature is, the less the hygroscopicity of “Hinoki” (Chamaecyparis obtusa) or “Kuromatsu” (Pinus Thunbergii) Wood becomes, but when the latter wood is more resinous than the normal condition, its hygroscopicity becomes more on the contrary.
2 In the range of 60-115°C, the decrease of equilibrium-weight in wood is mainly due to the discharge of its moisture. It seems that the decomposition of the wood-substance will slowly take place in case over the temperature 115°C.
3 The components of wood lost by such a treatment are comparatively little in “Hinoki”- or “Kuromatsu”- wood in the normal condition (2.5% and 3.7% respectively at the 130°C 96 hours-treatment); but in the resinous wood of “Kuromatsu”, it is not the case (9.8% at the same treatment).
4 As to the result of six hours extracton by Alcohol-Bensol from the test-piece (20mm×20mm×35mm) of “Hinoki” or “Kuromatsu”-wood, the longer the duration of heat-treatment of it at high temperature is, the lower the percentage of extracted materials is obtained, but the resinous wood of “Kuromatsu” the relation is reverse.
5 The shrinkage of “Hinoki” -wood which occurs by the heat-treatment is little in tangential or radial-direction and in volume. For instance, the volume-shrinkage is only 1.2% at the 130°C 96 hours-treatment.
