Influence of artificial weathering on the colour of wood Eucalyptus benthamii Maiden et Cambage treated with different finishing products

Eucalyptus benthamii has been identified as one of the main forest species for planting in the southern region of Brazil due to its resistance to low temperatures. Current studies with the species are restricted to forestry and the processing of wood from short-rotation plantations. However, the greatest added value occurs in processing, where the application of paints and varnishes can change the characteristics of the wood. The objective of the study was to evaluate the colour changes of E. benthamii wood, coming from long rotation plantations, subjected to artificial weathering, with two finishing products. The surfaces of the pieces were treated with marine varnish and power stain and subjected to three cycles in the weathering chamber (240 h, 480 h, and 720 h), following the standard ASTM G154 (2006. Standard practice for operating fluorescent light apparatus for UV exposure of nonmetallic materials (ASTM G154-06)). To measure colourimetric parameters, a Konica Minolta colourimeter (model CR-400) was used. The artificial weathering process caused darkening of the wood and a very appreciable variation in the surface colour after 240 h. After 720 h, all samples showed a tendency towards a yellow–brownish tone, with a standardisation in colour after accelerated ageing. This characteristic is interesting for marketing, considering consumers’ preference for the natural colour of wood.