Effects of Wood Drying Schedules on Fluid Flow in Paulownia Wood

Effects of three drying schedules on fluid flow were studied in the sapwood and heartwood of Paulownia wood (Paulownia fortunei). Boards with a commercial thickness of 5cm were randomly dried to a final moisture content of 8 +/- 2% using a mild (T6E3), a moderate (T6E4), and a severe (T7E4) drying schedule. Permeability measurement was carried out when specimens reached the final moisture content. Results showed a significant difference in the specific gas permeability as well as liquid permeability of the boards dried under the three drying schedules. Furthermore, a significant difference was observed in the gas permeability of sapwood and heartwood, dried under the different schedules, but not much significant difference was seen in the liquid permeability between sapwood and heartwood. T6E3 had the highest liquid permeability; furthermore, it was reported to have resulted in the lowest warping and most homogeneous moisture profile. This mild schedule is therefore recommended for commercial drying of Paulownia wood when further preservation and impregnation processes are planned for the dried boards. In the meantime, it is concluded that the age and drying schedule have significant effects on the formation of tyloses, significantly affecting gas and liquid permeability in Paulownia wood.