The effectiveness and resistance to weathering of four water repellent treatments, a commercial timber stain, and an oil-based clear finish, was assessed using 20x20x6 mm³ samples of untreated, copper-chrome-arsenic (CCA)-treated, and tributyltin oxide (TBTO)-treated radiata pine exposed to the weather over a four month period. The water repellency of each preservative/water repellent combination was measured by retrieving samples from an exposure rack on a monthly basis and recording weight increase on water immersion. The results were analysed with regard to the water repellency of each water repellent/preservative combination as a function of time. Significant increases in water absorption were noticed in most sample sets three to four months after initial exposure. The relative effectiveness of the different water repellent treatments varied according to the nature of any preservative treatment of the samples.

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