This study focuses on the effects of UV radiation and water spray on different types of modified wood. Therefore, thermally modified samples (T), wax impregnated samples (W) as well as thermally modified and subsequently wax impregnated samples (TW) of hard- and softwood were prepared. During the thermal treatment, for a specific period of time, the wood was exposed to 180°C in a nitrogen atmosphere. The wax impregnation (hard wax) was performed at approximately 120°C within the pilot impregnation system.
Artificial accelerated weathering tests were carried out on each sample type as well as on the unmodified control sample. In accordance to EN 927-6, 12 artificial accelerated weathering test cycles were run. Each cycle started with a period of condensation at 45°C (24 h), followed by 48 sub-cycles composed of UV radiation (2.5 h) at 60° and water spray (0,5 h). Gloss and colour measurements were performed before and after the weathering test.
After the intensive artificial accelerated weathering, the colour and gloss parameters of all modified wood materials became almost similar to those of the tested control samples. In total, all wood samples revealed increasing lightness L* and decreasing chromaticity C*. For the wax impregnated samples, the most significant loss of gloss G was already observed after the 1st weathering cycle due to the wax partly washed off.
Keywords: wax impregnation, thermal modification, artificial accelerated weathering
Authors
Baensch F.
Wood Chemistry, Wood Physics and Chemical Engineering, Eberswalde University for Sustainable Development, Eberswalde, Germany
Cordes D.
Wood Chemistry, Wood Physics and Chemical Engineering, Eberswalde University for Sustainable Development, Eberswalde, Germany
Melcher E.
Thünen Institute of Wood Research, Hamburg, Germany
Pfriem A.
Wood Chemistry, Wood Physics and Chemical Engineering, Eberswalde University for Sustainable Development, Eberswalde, Germany
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