Abstract
Uncoated sugi (Japanese cedar, Cryptomeria japonica D.Don) heartwood or sugi coated with penetrating or film-forming coating were exposed to natural weathering. Further, three types of accelerated weathering tests were performed. One test was conducted under an artificial sunlight irradiance of 60 W/m2 based on JIS K 5600-7-7 (filtered xenon-arcradiation, method 1, cycle A). The remaining two tests were performed at 105 W/m2 (1.75-fold) and 150 W/m2 (2.50-fold). The color difference, water repellency index, and gloss of the specimens were evaluated as indicators of weathering. We observed that the changes in these weathering indicators were accelerated by increasing the irradiance; however, the effects differed among various indicators and depended on the coating types. The changes in color difference, water repellency index, and gloss during these accelerated weathering tests did not significantly differ from those observed during natural weathering.
