The weatherability of colored architectural coatings is evaluated by a 4-years outdoor exposure test at various areas. Gloss retention, differences of brightness and value b* along yellow-blue axis were applied by a multivariate analysis referring estimated environmental degradation factors, 1) equivalent environmental temperature based black panel thermometer, 2) solar ultraviolet dose, 3) wetness time and 4) freezing/thawing cycle. Value of delta-L, an element of color difference, of yellow samples modified by those of white one were almost constant and did not related with referred factors. Therefore, the traditional evaluation system based mainly on color difference may be reducing accuracy.
