Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modi...

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Bibliographic Details
Published in:Coatings (Basel) 2017-10, Vol.7 (10), p.172
Main Authors: Pánek, Miloš, Oberhofnerová, Eliška, Zeidler, Aleš, Šedivka, Přemysl
Format: Article
Language:English
Subjects:
Artificial weathering tests
Cafeterias
Coating effects
Contact angle
Durability
Exteriors
Gloss
Leaching
Microcracks
Moisture content
Oak
Protective coatings
Rain water
Scanning microscopy
Service life
Tannins
Titanium oxides
Ultrasonic testing
Weathering
Wood
Wood products
Zinc oxide
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Summary:The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modified using UV-stabilizers, hindered amine light stabilizer (HALS), and ZnO and TiO2 nanoparticles before the application of a commercial hydrophobic topcoat. A transparent oil-based coating was used as a control coating system. The artificial weathering test lasted 6 weeks and colour, gloss, and contact angle changes were regularly evaluated during this period. The changes in the microscopic structure were studied with confocal laser scanning microscopy. The results proved limited durability against weathering of both tested hydrophobic coatings. The formation of micro-cracks causing the leaching of degraded wood compounds and discolouration of oak wood were observed after 1 or 3 weeks of the weathering test. Until then, an oil-based coating film had protected the wood sufficiently, but after 6 weeks the wood was fully defoliated to its non-homogenous thickness, which was caused by the presence of large oak vessels, and by the effects of specific oak tannins. Using transparent hydrophobic coatings can prolong the service life of the exteriors of wood products by decreasing their moisture content. Without proper construction protection against rainwater, the hydrophobic coating itself cannot guarantee the preservation of the natural appearance of wood exteriors.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings7100172