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Two experimental techniques were used to test the water permeability of two Korean hardwood species: diffuse porous Populus tomentiglandulosa T. Lee (eunsasi poplar) and ring porous white oak, Quercus serrata Thunb (konara oak). The fi rst technique measured the void volume fi lled at different moisture content (MC) levels. Samples were treated with water via a schedule of full-cell impregnation. A signifi cant relation between MC and permeability (the fractional void volume) was found. A reduction in liquid permeability was observed at MC above the fi ber saturation point (FSP), whereas the opposite result was observed at MC below FSP due to the effect of the voids available in the wood. However, the differences of increased permeability from MC level 20% to 0% were found satistically the same in either wood species. The second technique measured the speed of liquid penetration in vessels, fi bers, and rays with no application of external pressure. In this method, liquid fl ow was captured via video and the penetration speed was measured. Vessels, fi bers, and rays in poplar were found to be more permeable than those in oak. Different anatomical factors such as cell diameter, cell length, pit number, pit aperture area, and thickness of the pit membrane seemed to be responsible for the variation of liquid fl ow rate in different cells of the two hardwood species.

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The safranine impregnation differences in Pinus koraiensis, P. densiflora, P. rigida, and Larix kaempferi were studied. Among them, P. koraiensis conducted higher depth of safranine in radial and L. kaempferi in longitudinal direction. High magnification was used to observe the safranine penetration behavior in longitudinal direction especially in longitudinal tracheids. Safranine impregnation in longitudinal tracheids was captured in digital video mode to observe the formation of curved and flat air-safranine meniscus. Given the tracheid radius 16-20 µm, surface tension of water at 72 dynes per centimeter at 23°C and a contact angle 30°, the capillary pressure ranges from 0.06 to 0.08 bar. The lower the lumen diameter is, the higher the capillary pressure is. It was assumed that due to the differences of total water pressure under the safranine-water interface and total air pressure above the interface, curved meniscus was formed in the cell lumen.