What is the chalking of the paint film and how is it determined?

In the atmosphere, the coating film is affected by ultraviolet rays, oxygen, water, chemicals, etc., and the film-forming material 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 coating has a slight powdering property, such as self-cleaning on the outside, which can keep the coating clean and beautiful.

At present, there are several methods for measuring pulverization.

(1) Powder 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 on the photo printing paper with the standard photo. In the standard photos, the ones with obvious pulverization are taken as N90 points, which are №2 , №4, №6 and №8 in sequence , and the ones without pulverization are taken as №1o.

(2) Gravimetric method

Put the silk cloth on the sample plate, 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 photoelectric gloss meter at 6o°, when the surface gloss of the sample plate drops by 5o%, it is the beginning of chalking.

(4) Use the index finger or middle finger of the right hand to rub the sample with appropriate force for a few times (the scratches are 5-7 cm long), and then compare it with the standard photo. The one without chalking is grade O, and the one with slight pulverization is grade O. Grade 1, significant pulverization is grade 2, strong pulverization is grade 3, severe pulverization is grade 4