This study investigates the effects of different wood varnishes on the surface color properties of heat treated wood. Samples prepared from Oriental beech (Fagus orientalis L.) and Scots pine (Pinus sylvestris L.) are subjected to heat treatment at 190, 200, and 210 ° C for 2 h. Sample surfaces are then covered with cellulosic (SZ), synthetic (ST), polyurethane (PU), and water-based (SB) wood varnishes, and the color properties of samples are determined according to the three-dimensional CIEL*a*b* color space. Results show a decrease in the L* and b* values of samples by 64% and 70%, respectively, depending on the process temperature after heat treatment. The a* value increases by up to 96% for Scots pine samples and up to 56% for beech samples. Color values of heat treated samples change significantly after varnish is applied; L* values of all samples are reduced compared to unvarnished samples and samples are seen to darken. However, the a* value of heat treated Scots pine samples increases significantly after varnishing, while that of heat-treated beech samples at high temperatures (200 and 210 °C) generally decreases. Nevertheless, the b* value decreases significantly in both wood species subjected to application of PU and ST varnishes, and the total color change (ΔE*) of varnished specimens is generally higher for samples heat-treated at 200 °C. Results show that ST varnish has the largest effect on color change and SB varnish has the smallest effect. The use of SB varnishes is thus preferable when it is necessary to preserve the color of samples from either species following heat treatment.
Cite (Atıf) : Pelit, H., 2017. The effect of different wood varnishes on surface color properties of heat treated wood materials. Journal of the Faculty of Forestry Istanbul University 67(2): 262-274. DOI: 10.17099/jffiu.300010