Abstract
In the present study, liquid penetrability of smoke-heated sugi (Cryptomeria japonica D. Don) wood was evaluated. The sugi log with bark was smoke-heated directly for 40 hours at a temperature inside a log of 80°C. After smoke heating, specimens obtained from non-and smoke-heated woods were impregnated with a commercial fire retardant under several vacuum conditions, and then weight percentage gain (WPG) was determined. In addition, some characteristics including mechanical property, of the prepared fire-retarding woods were investigated. The rupture ratio of pit membranes increased in both heartwood and sapwood by smoke heating. The WPG after impregnation with the reagent increased greatly in smoke-heated heartwood. Residual weight of specimen after burning test increased with the increase of vacuum pressure for the impregnation. Almost no differences in the modulus of rupture in bending were found between the control and impregnated woods. However, the modulus of elasticity increased with increase in the WPG. The results obtained here suggest that smoke-heating technique gave great improvement of liquid penetrability in sugi heartwood.
