The samples were exposed to contamination for a period of time by appropriate methods, and then the color difference, gloss change and whether there were foaming and falling off of the coating were evaluated. Pollution resistance test is mainly used to
evaluate the influence of pollutants in supply-demand negotiation on the coating of color coated sheet. Common pollutants include diluted mineral acids, acetic acid, soap solutions, detergent solutions, ethanol, light fluids and other volatile reagents,
fruit juice, oil and fat, condiments, beverages, lubricants and greases, shoe oil, lipstick, marking pens, etc. After the test, the samples can be evaluated according to GB/T 1766-1995 standards, such as loss of light, discoloration, foaming and shedding.
Three test methods are commonly used in pollution resistance tests.
(1) Drop test (capping): The contaminant is added to the surface of the sample and immediately covered with a surface dish. The test time is recommended to be 24 hours.
(2) Drop test (without cover): the pollutant is added to the surface of the sample and exposed to the atmosphere. The test time is recommended to be 24 hours.
(3) Impregnation test: The sample is impregnated in pollutants, and the impregnation time is agreed between the supplier and the demander.