The Influence of Artificial Weathering on the Adhesion of Some Varnishes Applied to Thermally Treated Iroko and Ash Woods

Abstract

In this study, waterborne and solventborne varnishes were applied to the surfaces of ash (Fraxinus angustifolia Vahl.) and iroko (Chlorophora excelsa) woods which were heat treated at 190 degrees C for 1.5 h and 212 degrees C for 2 h according to the thermowood method. The influence of 576 h of aging process on varnish adhesion was determined by pull-off test according to ASTM-D 4541 in UVB-313 EL type aging device. As a result, wood species, varnish type and aging time were found to have a different level of influence on the adhesion strength of varnish layers. The highest adhesion value of 4.804 MPa was obtained in the sample with one-component waterborne varnish applied to ash wood, which was heat treated at 190 degrees C for 1.5 h and aged with UV-B lamp for 144 h.