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Publication: Forest Products Journal
Authors: Puettmann Maureen E|Schmidt Elmer L
Reference ID: 47(10):47-50
Publish Year: 1997
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Title: Boron diffusion treatment of aspen lumber stored under various relative humidities
Description:
This study was designed to determine if boards of a relatively refractory wood species, quaking aspen, could be effectively treated with a borate preservative using traditional dip-diffusion methods. In addition, various solution concentrations and storage conditions were tested and their effects on diffusion were compared. Boards dipped in Tim-Bor® (U.S. Borax, Inc.) were stored uncovered and stickered in controlled rooms set at various relative (RHs) to provide different equilibrium moisture contents. Chemical analysis of boron content from aspen boards indicated that after 8 weeks of storage in controlled rooms of 86 and 92 percent RH, boards had core retentions of 0.04 to 0.37 percent boric acid equivalent. The final moisture contents of treated lumber were 54 and 49 percent for boards treated with a 15.6 percent BAE solution and 70 and 58 percent for boards treated with a 34.7 percent BAF solution when stored in rooms at 86 and 92 percent RH, respectively, indicating that diffusion could still be occurring. After 4 weeks of storage, 61 percent or greater of the board cross section was penetrated at a concentration of 0.25 percent or higher as determined by spot test indicators for the two dip solutions. Results from this study indicate that aspen boards can be adequately treated with Tim-Bor using traditional dip-diffusion methods. Under restricted drying conditions of high humidity and high temperature, a sufficient preservative loading was obtained for control wood decay fungi and wood-destroying insects.
This study was designed to determine if boards of a relatively refractory wood species, quaking aspen, could be effectively treated with a borate preservative using traditional dip-diffusion methods. In addition, various solution concentrations and storage conditions were tested and their effects on diffusion were compared. Boards dipped in Tim-Bor® (U.S. Borax, Inc.) were stored uncovered and stickered in controlled rooms set at various relative (RHs) to provide different equilibrium moisture contents. Chemical analysis of boron content from aspen boards indicated that after 8 weeks of storage in controlled rooms of 86 and 92 percent RH, boards had core retentions of 0.04 to 0.37 percent boric acid equivalent. The final moisture contents of treated lumber were 54 and 49 percent for boards treated with a 15.6 percent BAE solution and 70 and 58 percent for boards treated with a 34.7 percent BAF solution when stored in rooms at 86 and 92 percent RH, respectively, indicating that diffusion could still be occurring. After 4 weeks of storage, 61 percent or greater of the board cross section was penetrated at a concentration of 0.25 percent or higher as determined by spot test indicators for the two dip solutions. Results from this study indicate that aspen boards can be adequately treated with Tim-Bor using traditional dip-diffusion methods. Under restricted drying conditions of high humidity and high temperature, a sufficient preservative loading was obtained for control wood decay fungi and wood-destroying insects.
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