The spraying and polishing of the radiator are very important aspects in the pre-treatment process, because it directly affects the later production process and also affects the life of the radiator.

Cast iron radiators are basically sandblasted or shot blasting, which is a typical physical mechanical method. Sand blasting and shot blasting are methods in which sand or steel shots are sprayed to the surface of the workpiece to remove foreign matter on the surface of the workpiece to obtain a rough surface to facilitate coating. The treatment method of jet sand is called sand blasting, and river sand, quartz sand, etc. can be used; the processing method of jet steel shot is called shot peening, and steel shots and metal fragments can be used as blasting materials.

Sandblasting and shot blasting are relatively efficient, simple in operation, suitable in surface roughness, and good adhesion of the coating film. There is also a chemical treatment method, although the cost is low, but the pollution is serious.