Summary
Western red cedar panels, one coated with a soft latex-based acrylic polymer clear coating and the other uncoated, were exposed outdoors under a series of cut-off filters for 50 weeks. FTIR-ATR spectra of the panels showed that the extent of delignification increased with decreasing wavelengths of the solar radiation incident at the wood surface. The results support the proposal that it is the UV component of sunlight that is primarily responsible for the degradation of lignin. The extent of loss of lignin from the surface of the exposed coated panel was significantly less than that for the exposed uncoated panel suggesting that the coating confers some protection from weathering to the underlying timber. Colorimetric measurements also showed that the degree of discoloration of the panels is related to the wavelength of the radiation penetrating the wood surface.
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This work was supported financially by ICI Dulux Australia and the Australian Research Council. The authors also express their appreciation for helpful discussions with G. J. Wilson of the Commonwealth of Australia Scientific and Industrial Research Organization (C.S.I.R.O.) and I. Leaver of Dulux Australia
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MacLeod, I.T., Scully, A.D., Ghiggino, K.P. et al. Photodegradation at the wood-clearcoat interface. Wood Sci.Technol. 29, 183–189 (1995). https://doi.org/10.1007/BF00204584
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DOI: https://doi.org/10.1007/BF00204584