Leachability and Decay Resistance of Tetraphenylborate Salt-Treated Wood

Summary In order to reduce the leachability of boron compounds in wood, the double treatment of tetraphenylborate sodium salt [(C6H5)4BNa] (TPBNa) with potassium chloride (KCl) or tetramethylammonium bromide [(CH3)4NBr] (TMABr) was investigated by impregnating them into sapwood specimens of Japanese cedar (Cryptomeria japonica) to form insoluble salts of tetraphenylborate tetramethylammonium or tetraphenylborate potassium. The reduction of boron retention in treated wood specimens after the waterleaching test was very small, showing the good fixation of boron compounds in wood. The double treatment of TPBNa salts with TMABr or KCl solution also showed an excellent decay-resisting effect against both Coriolus versicolor and Tyromyces palustris at low boron retention.