GB/T 9264-2012 "Paints and varnish sag resistance assessment" is a national standard for evaluating the ability of liquid coatings to resist coating sagging due to gravity during vertical surface application. The standard is equivalent to the international standard ISO 16862:2003, which replaces the old version GB/T 9264-1988 and extends the scope of application from Paints to all liquid coatings. The standard specifies two core test methods: one is to use a scaled multi-groove sag coating applicator to scrape parallel wet-film strips of different thicknesses on a horizontal test plate and then place them vertically for observation; the other is to use a spray gun to lame plating directly on a vertical substrate. The key to the test is to determine the maximum wet film thickness of the coating that does not produce sag phenomenon (such as teardrop-like, curtain-like sagging) during the drying process. The main testing instruments include sag coating applicator (usually 10 wet-films with a thickness difference of 25 microns can be scraped) and wet film thickness tester for verifying coating uniformity. This standard is an important basis for the coating industry to control the construction mass of complex parts such as vertical surfaces and corners.