Effect of steaming and hot-water soaking on the dryability of some Indonesian woods.
Fifteen species of wood from Indonesia (Albizia falcataria [Paraserianthes falcataria], Hopea mengarawan, Parinari corymbosa [Maranthes corymbosa], Shorea javanica, Dracontomelon mangiferum, Elmerrillia celebica, Calophyllum inophyllum, Quercus sp., Mimusops elengi, Altingia excelsa, Dacrydium beccarii, Planchonia valida, tectona grandis, Aleurites moluccana, Podocarpus imbricatus [Dacrycarpus imbricarpus]), which ranged in specific gravity [relative density] from 0.27 to 0.78 (green volume basis), were steamed for five hours at 100°C in near saturation condition, or soaked in hot-water for 48 hours at 70°C. The woods were than dried to equilibrium moisture content at nominal 50% relative humidity and 45°C. The drying times at 25% moisture content (MC), drying rates at 15 and 50% MC, diffusion coefficients, and volumetric shrinkages were compared with matched untreated controls. In most cases, the drying times of the steamed and hot-water soaked samples were less than those of the untreated. The drying rates and diffusion coefficients of treated samples generally increased, but the magnitude of the increase was species-dependent. The treated samples shrank more than the untreated controls, owing partly to removal of extractives. The partial removal and redistribution of extractives affected the drying rates of some woods.