This project was to complete the link from research to commercial production of borate-treated glulam, a value-added new product with appealing performance characteristics in the areas of fire-resistance, mold, insects and decay. The objectives of this project were to eliminate the impediments to commercial production that were identified in a previous project, and provide needed information on strength characteristics of borate-treated lumber compared to untreated lumber.
Two methods of adding borate compounds to plywood panels were investigated. One method was patterned after successful efforts to incorporate zinc borate into OSB panels, where the borate is added to the adhesive. Zinc borate, which has shown some success in OSB, was however not sufficiently soluble and was replaced with a sodium borate. Method two involved the more traditional approach in pressure-treating wood veneers with a borate solution. A commercial borate compound (Timbor®) was used. The treatment target in each case was 2 % boric acid equivalent (BAE), which is the normal level being applied to solid wood. Borate addition to the adhesive was not successful for plywood due to the high level of borate required relative to the adhesive quantity. Treating of wood veneers prior to bonding yielded better panel bond quality results but showed large variation in borate retention levels within and between veneers. Treatment at the 2 % BAE target level did not produce panels with adequate bond quality. Treatment to 1 % BAE showed more promise but there were insufficient panels at the lower BAE level to allow for any evaluation of termite resistance.