The coating is generally composed of film forming materials, fillers (pigments and fillers), solvents and additives. Sometimes the composition will change slightly according to the performance requirements, for example, there is no pigment or filler in the varnish, and there may be no solvent in the powder coating.

Generally speaking, coating is a material that can be coated on the surface of the object to be coated and can form a firmly attached continuous film. It can be inorganic, such as electroplating copper, electroplating nickel, electroplating zinc, etc. It can also be organic, such as most organic polymer materials, which constitute the main part of the coating market today.