In this paper, we propose a fast method to simulate aging degradation for a wood image color using real wood color values measured by exposure testing. The exposure testing elucidated a relationship between wood colors and weather parameters on testing location from data measured in about one year. Our proposed method can simulate discoloration of woods at any locations by inputting temperature, rainfall and insolation from the relationship. Furthermore, our proposed method can simulate discoloration of woods attached outer wall of buildings. We prepare a 3D building model, and calculate occlusions of the model. Our method can simulate discoloration of woods taking ambient environment of the wood into account by increasing and decreasing temperature, rainfall and insolation to input our method using the occlusion, i.e., woods near ground discolor fast by splashing rainfall.

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In this study, we investigated the effects of re-finishing on the extension of service life for water-borne wood-preservative semi-transparent coatings. In previous reports, we exposed sugi heartwood vertical-grain specimens finished with one of six commercially available water-borne （semi-film-forming） or two solvent-borne （as control samples；penetrating and semi-film-forming） wood preservative semi-transparent coatings to natural weathering for 24 months（ Exposure I）. We then re-finished the specimens with the same coatings（ either unsanded or sanded before re-finishing）, and recommenced natural weathering （Exposure II）. In this study, we measured time-dependent changes in the color difference and water repellency index of the specimens over 54－68 months of Exposure II （accumulated total of 78－92 months）, then evaluated the weatherability of the samples. From these data, we calculated the service-life extension ratio（ months over which the color difference or water repellency index reached the reference service life in Exposure II/ months over which the color difference or water repellency index reached the reference service life in Exposure I）. The calculation results were 1.7 and 2.3 for the unsanded and sanded-before-re-finishing specimens, respectively. These results indicate that specimens that had been sanded before re-finishing yielded greater service-life extension. Moreover, we found the performance ranking before and after re-finishing to be relatively highly correlated.

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