Abstract: The principle of permeability control of wood was studied. The results showed that the main factors affecting permeability of wood were the effective radius and the number of pit membrane openings. The permeability of wood which has large and many pit membrane openings is high. The smaller an opening is, the bigger the capillary tension at the gas-liquid interface in the opening is and the more difficult the impregnation of wood with liquid is. An impregnation pressure which is equal to the capillary tension at the gas-liquid interface in the pit membrane opening and enough to overcome the tension must be applied to the wood when the deep impregnation of wood with liquid is needed. One effective measure to improve the impregnation of wood seems to increase the radius of pit membrane openings and their number in order to reduce the capillary tension and the applied impregnation pressure, and subsequently to increase the flow rate and the permeability.

Key words: Permeability, Flow rate, Gas-liquid interface, Capillary tension, Pit membrane opening