Maderas: Ciencia y Tecnología (Apr 2023)

Effects of artificial weathering on the surface properties of coated radiata pine

  • Sirri Sahin,
  • Bruno Esteves,
  • Ahmet Can,
  • Hüseyin Sivrikaya,
  • Idalina Domingos,
  • José Ferreira,
  • Ümit Ayata

DOI
https://doi.org/10.4067/s0718-221x2023000100429
Journal volume & issue
Vol. 25

Abstract

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Radiata pine boards were coated with two different methods A and B both beginning with a hydro primer and finishing with a mat oil but method A using an acrylic high gloss coating and method B three layers of an acrylic sealer in between. The samples were subjected to aging processes for 144 h, 288 h, and 432 h by using UV-A 340 nm lamps. The CIE L*a*b* and CIE L*C*H* coordinates were determined (L*, a*, b*, C*, ho*, ΔE*), gloss (perpendicular (⊥) and parallel (//) to the grain at 20°, 60°, and 85° angles) and surface adhesion strength via the pull-off method were tested before and after weathering. Results have shown that lightness (L*), decreases with weathering for both varnish applications with a higher decrease for the B coating system. Redness increased for both applications with no significant differences. At the same time there was a yellowing of the samples along the weathering period. Parallel and perpendicular gloss decreased for 20º and 60º angles while it increased for 85º angle. The adhesion strength of method A was higher and its decrease with weathering was smaller than for method B. Both varnish applications have proven to confer some protection against wood discoloration, but method A showed the best results and is therefore the best method to be used by radiata pine.

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