熱帯産木材の乾燥性について

The object of the present study is to examine the difference of drying time and the checks occured on the boards in oven drying.
In this paper are discussed the drying time and shrinkage or moisture content and drying check of tropical wood which has been believed to be very difficult to dry.
Five species used in the present experiments are White lauan (Shorea spp.), Red repoh (Chukrasia tabularis J. JUSS), Teak (Tectona grandis LINN.), Matoa (Pometia Pinnata FOREST) and Buvinger. The test specimens were cut in 20×70×150 mm.
The experimental results may be summarized as follows :
1) Fig. 1 shows the relation between drying time and the rate of shrinkage per unit time. Fig. 2 shows the relation between moisture content and the rate of shrinkage per unit time. The maximum value of the rate of shrinkage per unit time corresponded to about 40% moisture content. It seemed that this moisture content represented the transitional point of the rate of shrinkage per unit time.
2) It is shown in Table 1 the drying time required for decrease of moisture content from 60% to 10% for tropical wood in oven drying.
3) Fig. 3 shows the example of maximum end check after 5 hr. since drying was started. It is observed that the end checks are due almost to the ray tissues.