بررسي اثر چوب كششي بر كيفيت خشك شدن الوار تبريزي در كوره

The Impact of Tension Wood on the Kiln drying Quality of Poplar Lumber

This research was conducted to evaluate the negative impact of tension wood on the drying quality of poplar lumber using a desired drying schedule. Poplar lumbers (P. nigar) were prepared from Taleghan region. The logs with green moisture content were converted to 6 cm thick lumbers. The lumbers were then dried by three different methods. In the first method, the lumbers were air dried for about 2 months to the moisture content close to FSP and then were conventionally dried in a pilot kiln using T10E4 schedule. In addition, two mild drying schedules (TgE3 and T6E3) were used. Then, surface and internal checks and casehardening were investigated in the dried lumbers. No surface checks occurred in the dried lumbers, whereas internal checks along rays and annual rings developed in the lumbers dried by all three methods. Based on the similar researches conducted on the normal poplar boards, it can be concluded that the in contrast to the normal boards, the boards containing tension wood are sensitive to both types of internal checks, namely radial and tangential checks. In general, the drying defects in the lumbers dried by T6E3 schedule were satisfactory and this schedule is recommended to dry poplar lumbers containing tension wood. Keywords: Drying, Poplar, Tension wood, Internal check, Casehardening