High performance tannin resin-boron wood preservatives for outdoor end-uses

Fixation of boric acid as a low toxicity wood preservative to decrease markedly its leachability was undertaken. Preservative systems based on the cross-linking and hardening of condensed tannins by hexamine, where boric acid is complexed onto the network, were found to markedly slow down the leaching of boron. They significantly enhanced-wood durability before and after leaching once tested towards basidiomycetes according to the guidelines of EN 113. A particularly virulent fungal species was used for the tests. Further immersion of the wood so treated in hot unsaturated vegetable oil does yield comparable results.