Development of a Weatherometer to Accelerate the Surface Checking of Wood

IRG/WP 08-20388

R Ratu, P D Evans

There is significant interest in developing preservatives that are better at preventing wood from checking. Currently, however, there is no accepted test methodology for accelerating the development of checks in wood samples so information on the effectiveness of treatments at restricting checking can be obtained more quickly. This paper describes the development of a new type of weatherometer (Accelerated Check Tester) and associated weathering cycles to accelerate the surface checking of wood. The device permits the testing of realistic-sized decking board samples that are oriented horizontally and restrained by fixings. It uses computer-controlled water spray and infra-red heating systems to expose samples over a 5 day period to wetting and drying cycles. Desiccated air is also blown across the surface of samples to further increase the effectiveness of the drying cycle. The Accelerated Check Tester operated continuously and trouble-free for 24 weeks during an experiment, which examined the effect of different weathering cycles on the checking of southern pine and western red cedar decking samples. Samples exposed in the Accelerated Check Tester developed large numbers of checks, some of which were quite big, particularly those in southern pine samples. Weathering cycles that increased the severity of drying by increasing drying time or temperature did not significantly increase checking. Similarly, the inclusion of a freezing step in the weathering cycle had little effect on checking. In contrast, samples subjected to a cycle that included exposure to ultraviolet light developed significantly more and larger checks than samples subjected to any of the other cycles. Checking was much more pronounced in southern pine samples than in western red cedar samples. The Accelerated Check Tester should be a very useful tool for obtaining information on factors that affect the checking of wood. Furthermore, it could also allow companies developing wood preservatives and associated water repellent additives to rapidly obtain information on the ability of treatments to restrict checking and so shorten the development time for new wood protection systems.


Keywords: checking, weatherometer, preservatives, decking, testing, weathering, accelerated check tester, southern pine, western red cedar

Conference: 08-05-25/29, Istanbul, Turkey


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