The environmental cracking or checking of wood is an important problem with significant consequences for a range of wood products. We illustrate the importance of the problem by describing the impact of checking on the performance and longevity of railway sleepers (ties) and consumer decking. Checks develop when wood dries, and the mechanisms responsible for checking have been described in qualitative and quantitative terms. Drying checks become bigger when wood is exposed outdoors, and additional checks also develop. Our research has shown that exposure to UV radiation and re-wetting account, in part, for increases in checking of wood exposed outdoors. We describe how these factors increase the environmental checking of wood, and the effects of re-wetting on the direction and magnitude of strains that cause checking. Finally, we describe how strains that develop at wood surfaces exposed to wetting and drying are influenced by the surface topography of wood, which underpins the success of surface profiling as a way of reducing the impact of checking on the appearance of wood.
Keywords: Cracking, checking, UV radiation, mechanism, strains, profiling
Authors
Evans, P.D.
Urban, K.
Chowdhury, M.J.A.
Ratu, R.
Ribarits, S.G.
Cheng, K.J.
Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, Canada
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