Preliminary evaluation of boron release and biological resistance of wood treated with disodium octoborate tetrahydrate (DOT) and a water-repellent compound

Abstract

Wood specimens were vacuum-treated with disodium octoborate tetrahydrate (DOT) and a commercial water repellent compound. Leachates sampled from the leaching cycles for 10 days and extracts from treated wood specimens were analyzed for boron content. Treated wood specimens were exposed to wood degrading fungi in Petri dishes. Wood specimens were also subjected to termite resistance tests by using the subterranean termites. Treatments with the water repellent compound resulted in nearly 50% less boron leaching at 0.5 and 1% DOT concentration levels in comparison with DOT-only treated specimens. More boron release was seen in the specimens treated with 0.1% DOT and the water repellent compound when compared to either 0.5 or 1% DOT + water repellent compound treatments. Wood specimens treated with the compound and 0.5% DOT or more concentrations were well protected from fungal attack even after leaching course. All unleached specimens showed perfect protection against termites; however, mass losses in control specimens and leached specimens were nearly 30%. After treatments with 0.5 and 1% DOT and the compound, nearly 50% of total boron remained in these specimens after leaching course increased termite resistance of wood. The termite mortalities were in accordance with the mass losses that occurred in the specimens.

Key words: Dipropylene glycol monomethylether, boron release, water repellent, decay resistance, termite resistance.