Efeito de diferentes vernizes aplicados em cinco madeiras amazônicas submetidas ao intemperismo natural

Abstract

This study aimed to evaluate the behavior of wood species Apuleia leiocarpa (J. Vogel) J. F. Macbr (garapeira), Erisma uncinatum Warm (cedrinho), Hymenolobium petraeum Ducke (angelim-pedra), Mezilaurus itauba (Meisn.) Taub. ex Mez (itaúba) and Qualea albiflora (cambará), untreated and treated with polyurethane varnish (gloss) and stain (semi-transparent), submitted to natural weathering. The test specimens were prepared in size 2 cm x 2cm x 10 cm, with the larger dimension in the axial direction, totalizing of 144 specimens per species. For the implementation of the experiment, a platform with a metal mesh was used in the experimental area of the Universidade Federal de Mato Grosso, Sinop campus, to expose the samples to the weatherproof. The samples were submitted to 12 months of weathering, monthly four replications were collected per treatment and species, for the evaluation of colorimetric parameters L*, a*, and b*, equilibrium moisture. Equilibrium moisture results and colorimetric parameters were interpreted with linear regression analysis with the help of a software and subsequently held the means test, Tukey test, at 5% probability of error. The linear regressions made it possible to adjust and calibrate the statistical models estimating the equilibrium moisture and colorimetric standards L*, a* and b * for the five amazonian species treated and not treated with polyurethane varnish (gloss) and the stain (semi-transparent) exposed to natural weathering. The five studied Amazonian species have suffered color change caused by the leaching of wood chromophore substances with the action of natural weathering. In Ueq found as physical barrier varnish application of polyurethane (gloss) and make spot (semi-transparent) was not satisfactory, because there was no minimum difference between the treated wood and untreated. Thus it is concluded that both treatments have aesthetic functions embellishment of the timber , and not help protect against natural weathering