Thermal treatment of southern pine timbers with borates

Green, partially seasoned (air-dried, steam conditioned), or kiln-dried southern pine timbers were treated thermally using 15 percent disodiumoctaborate tetrahydrate solution. After treatment, sections were stored under nondrying conditions to allow for diffusion. Results showed that effective treatment meeting the AWPA minimum retention (0. 17 B2O3 pcf (2.72 kg/m3) in the outer inch) and penetration (2.5 in. (64 mm) or 85% of the sapwood) could be obtained only with certain combinations of seasoning, treatment, and diffusion storage. The best results in terms of both retention and penetration were obtained with material stored prior to treatment using a 10-minute hot bath time. Kiln-dried timbers could not be treated effectively. The results suggest that non-conforming treatment of green or partially seasoned timbers will require higher solution concentrations, higher hot bath temperatures, and/or longer diffusion periods to meet required standards. Results also indicated that treatment of smaller stock in dimension sizes (up to 2 in. (50 mm)) should be feasible.

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