Reason: Under the strong sunlight, the paint film is gradually damaged, the car paint will be burnt, and the paint surface will produce extremely fine cracks, which will continue to penetrate into the car paint until it "breaks through" the whole paint layer. This phenomenon is called cracking, which usually occurs on metallic paint. It is difficult to find with naked eyes at the initial stage of cracking. When the naked eye can detect it, it is already very serious, and the repainted metallic paint may crack, and the cracking phenomenon is serious and must be repainted. However, sometimes the resin in car paint will crack due to "shrinkage" due to the quality problem of painting. Preventive measures: paint coating can be protected once every two months or one and a half months, or beauty projects with mud mill and crystal wax can be protected.