In the atmosphere, the coating film is affected by ultraviolet rays, oxygen, water, chemicals, etc., the film-forming substance degrades and ages, loses its cohesiveness, and loose powder particles appear on the coating surface, which is pulverization. The pulverization resistance of the coating is related to the base material, pigment and its ratio. The paint has a slight powdering property, and if it has self-cleaning property on the outer wall, it can keep the coating clean and beautiful.
At present, there are several methods for measuring pulverization.
(1) Powdering Tester test method. It is to put the test instrument perpendicular to the surface of the sample, apply a certain pressure, and compare the amount of powder adhered to the printing paper with the standard photo. In the standard photo, the one with obvious pulverization is taken as the center 0 point, followed by Qin 2, Xin 4, Qin 6, and NQ8, and the one without pulverization is regarded as Qin 10.
(2) Weight method. Put the silk cloth on the template, add a certain weight, and accurately weigh the weight of the powder adhered to the silk cloth, accurate to 0.1 gram.
(3) Gloss method. Tested with a 60° photoelectric gloss meter, when the surface gloss of the sample plate drops by 50%, it is the beginning of chalking.
(4) With the index finger or middle finger of the right hand, wipe the sample with appropriate force for a few times (the length of the scratch is 5-7 cm), and then compare it with the standard photo. The one without powder is grade 0, and the one with slight powder is grade 0. Grade 1, significant pulverization is grade 2, strong pulverization is grade 3, severe pulverization is grade 4.