Effects of heated air drying on accelerating fixation of ACQ-D in wood

In order to clarify the effects of heated air drying on accelerating fixation of ACQ-D (Amine Copper Quat-Type D) in wood, Chinese fir wood samples were vacuum-treated with 1% ACQ-D solutions, prefixed for 48 hours at room temperature, and different post treatments were undergone including unwrapped air drying, wrapped air drying, unwrapped heated air drying, and wrapped heated air drying. The temperature in heated air drying was controlled at 50℃, and the duration of the treatment was 2, 6, 12, and 24 hours, respectively; the duration for air drying was 1, 2, 4, and 8 days, respectively. After post treatment, leaching tests were carried out and the percentage of copper leached from the samples was determined based on the copper amount remained in the samples after leaching tests. The results indicate that: 1) both air drying and heated air drying can improve the fixation of ACQ-D preservative in wood. And the effects become more obvious as the treated time increasing; 2) heated air drying is proved to be a better method than air drying in accelerating copper fixation since it requires shorter time to reach an excellent effect of fixation. In this study, a good resistance to copper leaching is obtained after heated air drying for more than 6 hours; 3) wrapping has different effects on air drying and heated air drying. It appears as a positive factor for air drying but negative for heated air drying. The reason may be that the heat transmission is blocked by the plastic film used for wrapping, which results in a low inner temperature of wood and finally slows down the copper fixation process in wood.