Abstract
Sugi heartwood specimens finished with commercially available wood preservative semitransparent coatings(seven water-borne[WB]and two solvent-borne[SB])were exposed to artificial weathering by a xenon lamp(JIS K5600-7-7)and fluorescent UV lamp (EN 927-6)and to natural weathering(45° inclination facing south in Tsukuba, Japan). We then evaluated the correlation between accelerated and natural weathering and the acceleration factors obtained in the xenon and fluorescent UV lamp tests. Changes in color and in the water repellency index indicated that 2-year natural weathering corresponds to a 2, 500-hour xenon lamp test(in which the acceleration factor was 7.0)and to a 12-week fluorescent UV lamp test(acceleration factor 8.7). Regarding the presence/absence of the coating and the coating types, we found that when the changes in color and the water repellency index were used as indicators of weatherability, the xenon lamp test provided a good simulation of the natural weathering of the specimens unfinished or finished with SB coatings. In contrast, we found that the fluorescent UV lamp test well simulated the natural weathering of the specimens finished with WB coatings, in terms of the performance ranking of the color difference and water repellency index.
