In an earlier study, it was shown that CCA leaching losses could be reduced over an accelerated leaching and short term natural weathering exposures by post treatment application of a commercial water repellent. In this report, the effects of this coating and two commercial CCA solution water repellent additives are evaluated after two years of natural weathering. Wood boards were pressure treated with CCA or CCA + WR additives and assembled into deck or fence units. Some of the CCA only treated fence units were dried and brush coated with a commercial water repellent finish. After exposure to accelerated weathering, the units were installed out-of doors and the concentration of water drippage collected during rain storms analysed and compared. The water repellent formulation applied after treatment was most effective in reducing CCA component concentrations in the leachate and drippage samples. The water repellent additives incorporated in the CCA solution, had a positive, but lesser effect on the CCA component concentrations in the drippage from the fence units, but had no significant effect on the CCA leached from the deck units. Concentrations of copper in the water drippage from CCA treated decks and fences without water repellent dropped over the 2 year exposure, but arsenic and chromium levels did not drop significantly with time.

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