engleski

Colour changes of modified oak wood in indoor environment

Recently, owing to its physical and aesthetic properties, wood flooring has been increasingly produced from the modified wood. Dark shades i.e. the appearance of tropical wood is achieved by its heat-treatment and ammonium-treatment. It is a known fact that wood is a photochemically unstable substrate which, as a result of lignin photooxidation, undergoes discolouration even indoors. The present work was aimed at establishing a degree to which UV irradiation causes discolouration of the heat-treated and the ammonium-treated wood. Discolouration of the uncoated wood samples and of those treated with four commercial transparent coatings (oil, UV varnish, one-component water-based varnish and two-component polyurethane varnish) was measured spectrophotometrically. The samples were kept under the UVA-351 lamps in the QUV Accelerated Weathering Tester over 32 days. Based on the obtained E* results it was concluded that after the aforementioned accelerated exposure the samples underwent discolouration. The most significant was recorded between the control samples (uncoated) and those coated with water-based varnish, whereas other coatings, most of all the two-component polyurethane varnish, had helped reduction of discolouration. The ammonium-treated oak wood showed superior stability to discolouration.

modified oak wood; QUV test; transparent coatings; photodegradation

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