Durability of Selected Transparent and Semi-Transparent Coatings on Siberian and European Larch during Artificial Weathering

Abstract

This paper compares the resistance of 20 commercial transparent and semi-transparent coatings applied to European and Siberian larch during artificial weathering in Xenotest. The change in gloss, colour, contact angle of wetting, resistance to Aspergillus niger and Penicillium brevicompactum moulds was evaluated, and visual changes at the top surface of treated wood species were measured. Overall, the durability of coatings on European larch was higher than that on Siberian larch. The most durable of the tested coatings was a thin-film, i.e., semi-transparent oil-based film containing TiO2 pigment and propiconazole fungicide. Of the transparent coatings, the most stable was a thick acrylic coating. Conversely, penetrating transparent oil systems had low colour stability and overall lifespan. Artificial weathering of all of the coatings resulted in a marked decrease in their resistance to moulds.

Effectiveness of Two Different Hydrophobic Topcoats for Increasing of Durability of Exterior Coating Systems on Oak Wood

“…The application of the top hydrophobic layer did not significantly improve the properties of less suitable coating systems during exposure (Figures 2-8, Table 5). In the case of oil thin layer systems, the positive effect of pigments on the overall service life and color stability (OL-8 and OL-9 -see Figures 2 and 5) was confirmed, which is consistent with other studies [28,41,42]. However, in the case of penetrating pigmented oil without the top hydrophobic layer OL-10, rapid leaching of coating and loss of functionality occurred.…”

“…For example, coating systems OL-10b and OL-10c were characterized by a relatively low color change ( Figure 2) and minimal decrease of contact angle ( Figure 5), but their overall visual degradation was quite pronounced (Table 5 and Figure 7). If the top layer of coating is degraded, but the penetrated layer remains, the significant visual changes occur, but the contact angle can be unaffected [8,41]. At the same time, it can be stated that coatings with better results of visual evaluation according to Table 5 (e.g.…”

“…Coatings 2018, 8, x FOR PEER REVIEW 10 of 15 Figure 7). If the top layer of coating is degraded, but the penetrated layer remains, the significant visual changes occur, but the contact angle can be unaffected [8,41]. At the same time, it can be stated that coatings with better results of visual evaluation according to Table 5 (e.g.…”

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

“…These properties are more likely connected with coating degradation and disruption than with chemical changes in wood [34,39]. Acrylate and oil coatings reached the best performance on larch wood also in study of Šimůnková et al [15]. In opposite, in the study of Sivrikaya et al [48], the better performance against atmospheric conditions on oak wood was recorded for alkyd coatings compared with other tested coatings.…”

“…Their advantage is the ability to protect wood and preserve the natural look and colour [13], but they have the disadvantage of not protecting the substrate wood against UV and visible light radiation as well as pigmented coatings [14]. The different performance of coatings is also caused by their polymer base [15], the type of solvent [16] or even by the underlying wood species [17,18]. Coatings protect underlying wood, but they are exposed to weathering process causing their degradation [17,19,20].…”