In the actual application of the coating, a dry coating film is formed due to the volatilization of various solvents in the mixed components. However, there are two aspects in the coating process that can significantly affect the gloss of the coating film surface, and its essence is still caused by the different surface roughness. First, there are many volatile solvents in coatings (especially solvent-based coatings). Different solvents have different volatilization rates due to their different physical and chemical properties. When the volatilization rates of these kinds of volatile solvents are similar, the surface of the coating film tends to be relatively flat, and the roughness is low, the gloss is high; otherwise, when the volatilization rates of different solvents are very different, the surface of the coating film tends to be wrinkled. The roughness becomes larger and the gloss becomes smaller. On the other hand, because there are some other additives in the coating, some float on the surface of the film and cause unevenness on the surface after forming a dry film, resulting in a small gloss.