Desempenho colorimétrico da madeira de espécies de clima temperado ao intemperismo em clima tropical

Abstract

The appearance of wood, including its color and texture, is one of the most important characteristics for its use in solid products such as furniture, cladding, and terrace decking. Weathering can cause significant changes in the color of wood products used in outdoor applications, affecting their market acceptance and long-term performance. This study evaluated the colorimetric performance of four temperate wood species (Picea abies, Pinus sylvestris – heartwood and sapwood, Fagus sylvatica, and Robinia pseudoacacia) exposed to natural weathering under tropical climate conditions (Aw) in southeastern Brazil for 52 weeks. Ten replicate specimens per species were tested, measuring 25 x 50 x 150 mm. Wood color was measured using the CIE-Lab* system with a portable spectrophotometer. The colorimetric parameters lightness (L*), red-green (a*), and yellow-blue (b*) chromaticity coordinates were measured and used to calculate the color difference (ΔE). Wood color was monitored weekly during the first four months of testing. Afterwards, measurements were taken at four-week intervals. A perceptible color change in all temperate species was detected after five weeks of outdoor exposure. The heartwood of Pinus sylvestris showed the highest color stability. It is noteworthy that the temperate species were tested under severe conditions, as no protective coating was applied to the specimen surfaces. Therefore, for future studies, it is recommended to expose specimens with surface finishing products such as varnish and waxes.