GB/T 9780-1988 "Test method for stain resistance of architectural coatings coatings" is a Chinese national standard, which stipulates a general test method for determining the stain resistance of architectural exterior coatings. It is suitable for various architectural exterior coating coatings, using fly ash as a source of pollution. Assess stain resistance by rinsing with water after painting the sample and measuring the change of reflection coefficient. Including instrument materials, test plate preparation, test procedures and evaluation of results. This standard has been replaced by GB/T 9780-2005.