Effects of species and moisture content on penetration of liquid in laser incised lumber by the passive impregnation method

Penetration of liquid by passive impregnation method for Douglas-fir (Pseudotsuga menziesii Franco), sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) was studied. Effects of initial moisture content of sugi (16, 43 and 70% moisture content) on liquid penetration were also studied. Dried Douglas-fir (mc = 14%) and sugi (mc = 16%), and green Japanese larch (mc = 45%) and sugi (mc = 70%) were treated by passive impregnation method for penetration analysis. It was observed that dried sugi had the highest level of liquid penetration both in length (170mm) and width (8 mm) for all measured sections followed by green sugi, green Japanese larch and dried Douglas-fir. In case of different initial moisture content, the highest absorption (624 kg/m(3)) and penetration (maximum 87 and 96% at cross and longitudinal surfaces, respectively) was observed for sugi having the lowest initial moisture content under the same passive impregnation conditions. Absorption and penetration decreased with the increase of initial moisture content for sugi. These results could help in designing incising pattern and density, as well as solving the problems related to high initial moisture content of wood for passive impregnation.