Passive impregnation of liquid in impermeable lumber incised by laser

Square lumber specimens of laser-incised Douglas fir (Pseudotsuga menziesii Franco) were treated with steam before dipping. Two types of steam (saturated steam and superheated steam), three steam-injection times (5, 10, and 20 min), four different time intervals (moving time) between steam treatment and dipping (immediate, 3, 10, and 30 min), and four different dipping times (0.5, 1, 3, and 12 h) were used in the study. The maximum absorption was 480 kg/m(3) when saturated steam was injected for 20 min and the specimen was immediately dipped into liquid for 12 h. Samples treated with this condition not only absorbed the maximum amount of liquid but also penetrated over 83.4% and 87.3% of the total area along and across the grain, respectively. The optimum conditions were then applied to laser-incised sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) where the absorption of liquid was 415 and 187 kg/m(3), respectively. It was shown that initial moisture content below the fiber saturation point was good for passive impregnation. The absorption of liquid and its distribution in wood indicates that it can be a good preservative treatment method for impermeable woods.