The influence of artificial weathering on the adhesion of some varnishes applied to thermally treated iroko and ash woods

<span style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">In this study, waterborne and solventborne varnishes were applied to the surfaces of ash (</span><i style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">Fraxinus angustifolia</i><span style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">&nbsp;Vahl.</span><i style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">)</i><span style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">&nbsp;and iroko (</span><i style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">Chlorophora excelsa</i><span style="color: rgb(51, 51, 51); font-family: &quot;Open Sans&quot;, sans-serif; font-size: 17.6px;">) woods which were heat treated at 190 °C for 1.5 h and 212 °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 °C for 1.5 h and aged with UV-B lamp for 144 h.</span>