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 solegel 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/BAd2.5:1, 5:1, and 10:1dwere 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.