Performance Characterization of Coatings on Treated-Wood

Coating performance is greatly influenced by the properties of the wood substrate. This study was focused on evaluating the performance of coatings on both preservative- and thermally-modified wood. A number of commercially formulated semi-transparent stains (Alkyd, Alkyd-Acrylic and PU) were applied on four different types of preservative treated and oil-heat-treated wood and their performances were evaluated in natural weathering exposure in Toronto, Canada. The results showed that the treatment enhanced the performance of the coatings. This enhancement occurred by reducing the water uptake by thermal treatment and preservative treatment with chromated copper arsenate (CCA). Even though wood treated with Cu amine-based preservatives had a higher water uptake than untreated wood, the erosion and color change of coating on Cu-amine treated wood was significantly lower than on untreated wood. There were some water-based formulations that had overall better performance than solvent-based coatings on thermally treated wood.