Comparison of Exterior Coatings Applied to Oak Wood as a Function of Natural and Artificial Weathering Exposure

Abstract

Artificial weathering can significantly reduce the testing time needed for proving coating durability, nevertheless its reliability is still not thoroughly proven. In this study, eight different transparent and pigmented coating systems, namely oil, acrylate, alkyd and urethane alkyd were evaluated through natural and artificial weathering tests on oak samples by measuring colour, gloss and surface wettability and by macroscopic and microscopic evaluation. The oil coatings performed well in wood colour stability evaluations, while the best gloss and wettability change results were noted for acrylate coatings. Pigmented coatings were characterized by significantly lower colour changes than transparent ones. The gloss and wettability changes were more sensitive to coating disruption than to total colour changes of coated wood associated with chemical changes in wood. The findings in this work showed that values of gloss changes and surface wettability for all types of coatings exposed to artificial and natural weathering resulted in significant differences from each other. The data obtained by artificial weathering method provide basic results of coatings durability and, ideally, natural weathering should be performed at the same time to support the results from laboratory tests by exposing wood under real conditions.

Improving sustainability in wood coating: testing lignin and cellulose nanocrystals as additives to commercial acrylic wood coatings for bio-building

“…Therefore, lignin application on coated wood affects its original colour, but this permits additional wood protection against UV light as lignin acts as UV absorber (Teaca et al 2019). Hence, according to Ozgenç et al (2020), lignin can provide colour stabilization when a waterborne acrylic coating is applied in outdoor condition, because transparent coatings require more frequent maintenance than pigmented coatings, as UV light penetrates and degrades the film layer and decomposes the wood underneath (Oberhofnerová et al 2019).…”

Bioinspired Living Coating System in Service: Evaluation of the Wood Protected with Biofinish during One-Year Natural Weathering

“…Spectroscopic techniques such as Fourier Transform Infrared Spectroscopy (FTIR) [15,16], Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) [17], and/or Fourier Transform Near Infrared Spectroscopy (FT-NIR) [18][19][20] are often used to investigate changes in functional groups of wood chemical components. Other aspects frequently assessed while evaluating the weathering process of materials include the determination of the surface roughness [21,22], wettability [23,24], or glossiness [18,25,26].…”

Performance of Exterior Wood Coatings in Temperate Climates

“…The early effects of weathering do not usually cause structural issues; rather most short-term weather results in a decline of the aesthetic attributes of wood surfaces that likely influenced the specification of wood in the first place. On uncoated surfaces or for surfaces where the coating has failed, the process of surface degradation generally begins Coatings have been the subject of considerable research [2,8,9,[11][12][13][14]. Most studies have evaluated generic finishes or have not identified brand names.…”