There is increasing demand for natural looking wood in exterior applications. If wood finished with transparent and semi-transparent coatings is to compete with other building materials that claim to be low maintenance, the time between re-finishing has to be considerably extended. The use of low-nutrient wood materials, carbon-based preservative treatments, and protective pre-coats that reduce photo-degradation may be able to reduce the maintenance requirements for exterior wood products. The effectiveness of various combinations of protection systems were investigated in field tests set up in Maple Ridge, BC and Saucier, Mississippi. This report describes the initiation of these tests and results after six months of exposure.
In general spruce heartwood samples performed better than the pine sapwood samples. The semi-transparent film-forming finish (F1) performed better than the transparent film-former (F2), which performed much better than the semi-transparent penetrating stain (F3). In general, preservative-treated wood performed better as a substrate than untreated wood. The protective pre-coats were relatively effective under the transparent film-former. Further evaluations are needed to determine the efficacy of the protective pre-coats under the semi-transparent film-former.