The objective of this study was to compare liquid water absorption of wood surfaces with and without coating, before and after artificial weathering. Samples of spruce, oak and sapelli were exposed to the EN 927-6 cycle for 1500 and 1850 hours and to the weathering produced by the Garner wheel for 1000 hours. Two highly pigmented coatings (solventborne and waterborne) and two semi-transparent stains (solventborne and waterborne) were applied on these species and exposed to weathering for the same exposure times. Water uptake was measured after soaking samples in water for 72 hours according to EN 927-5. Water absorption of both hardwoods were in the same range and lower than that of spruce. Exposure to the EN 927-6 weathering led to a significant increase in water absorption of uncoated wood with the biggest increase for oak. The increase in water absorption produced by the wheel was lower.The combination of water absorption measurement and artificial weathering gives more information about long-term performance of coatings than a single measurement of water absorption on fresh and unweathered coated wood. A decrease in water absorption due to weathering was observed for the two pigmented coatings whereas an increase in water absorption was noticed for the two semi-transparent products.All coatings tested had water absorption below the threshold of EN 927-2 of 175g/m² that classifies coating for stable substrate. However results showed that low water absorption was not a proof of the quality of the product.

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