Flavanoid biocides: Wood preservatives based on condensed tannins

Abstract

The condensed tannins are natural wood preservatives found in high concentrations in the bark and wood of some tree species. Condensed tannin-containing bark extracts from loblolly pine (Pinus taeda) were evaluated as wood preservatives using standard methods. Bark extracts by themselves did not cause any reduction in weight loss of pressure-treated wood blocks at the retentions tested. However, they do have efficacy as wood preservatives when complexed with copper(II) ions. The best experimental wood preservative formulation was a dual treatment using a sulphited bark extract first, followed by a CuCl₂ treatment. At some retentions, this method yielded wood blocks with greater resistance to decay by Coriolus versicolor than pentachlorophenol. A single stage treatment of extract plus copper using an aqueous ammoniacal solvent was also successful but not as effective as the dual treatment.

Citation

Laks, Peter; McKaig, Peggy A.; Hemingway, Richard W. 1988. Flavanoid biocides: Wood preservatives based on condensed tannins. Holzforschung 42(5):299-306