A wood treatment based on siloxanes and boric acid against fungal decay and coleopter Hylotrupes bajulus

A wood preservative based on tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and boric acid (BA) in volume ratio TEOS/APTES 1:1 and in molar ratio APTES/BA 50:1 was applied to wood by the sol–gel process. Standard EN 113 and mini wood block tests were carried out to determine the effectiveness against fungal decay. The same formulation applied by immersion was tested against larvae of the wood-borer insect Hylotrupes bajulus. This formulation showed good efficacy against Coniophora puteana, Poria placenta, and Trametes versicolor, even after a leaching procedure. It was also effective against the coleopter H. Bajulus. Different molar ratios of APTES/BA—2.5:1, 5:1, and 10:1—were tested with a leaching procedure in accordance with EN 84 to determine the best fixation of boric acid into the wood. The ratio APTES/BA 5:1 was found to be the most effective for fixing boron into wood.

► A preservative based on TEOS, APTES and boric acid was applied to wood by a sol–gel process.
► The best ratio APTES: Boron in terms of impregnation and B fixation into the wood resulted to be 5:1.
► Effectiveness against brown rot and white rot decay even after a leaching procedure was shown.
► Effectiveness against the coleopter Hylotrupes bajulus, when applied by immersion, was also shown.