Comparison acceleration test results with outdoor exposure one on rain streak dirt for building paints

Abstract

The rain dropped on draining board flows down on the building external wall during raining. And then the flowed rain marks remain on the wall as dirt after raining. The dirt mark is called “rain streak dirt” in this paper. The rain streak dirt often can be seen where under of window, top of parapet, and etc.. The rain streak dirt is caused by the flowing water with dust accumulated on the draining board. The acceleration test method was developed to evaluate the dirt-resisting building external materials. This paper describes the comparison between the outdoor exposure test results and the acceleration test results for building paints. The steel sheets coated with 13 kinds of paint were used as test specimens. As a results, the higher water contact angle of specimen, the grater the color difference. In addition, the color differences of acceleration test results are larger than that of outdoor exposure test at six months.