The improvement of the permeability of wood by underwater shock wave

Sugi (Cryptomeria japonica D.Don) wood generally has the so-called black heartwood, which contains the extremely high moisture content. Although subjected to the drying process, it is difficult to be dried up completely so that Sugi wood does not have the sufficient strength for use. The reason is that during drying process, the bordered pit membrane on traicheids closes faster near the heartwood in Sugi wood so that the internal moisture is not easily come out to the outside. At the mean time, it also makes very difficult to saturate the rotten-proof chemicals into the dried Sugi wood to have it become an additionally valuable wood. In this paper, we will develop an underwater shock wave technique to treat the pre-dried wood for the improvement of the drying property as well as the permeability and strength of Sugi wood by selectively fracturing the bordered pit membrane. The result indicates a very remarkable improvement on the drying time. The mechanism of the fracture of the bordered pit by underwater shock wave will be further studied in the future.