1. Top paint film: RPE, SMP, HDP, PVDF, Other paints.

Function: It functions as a sunlight proof cover,especially prevent the destroy by the ultraviolet rays.When the top paint film reaches a certain thickness, it forms a compact cover,and reduce the water and oxygen permeability.

2. Primer paint film: Polyurethane, Epoxy, PE.

Function: Strengthen the adhesiveness between the top paint film and the basemetal. Even permeable water happens, the top paint film will not peel off.There is corrosion inhibitor which is corrosion resistance.Polyurethane is necessary for higher processing flexibility and weather resistance requirements.

3. Passivation layer Function: Increase the adhesion between the metallic layer and coating film. Extend life span also.

4. Metallic coating Function:The metallic coating provides the fundamental protection for the steel.The popular coating metal are galvanized, galvalumed and other alloyed metals.

5. Substrate steel Cold rolled steel is usually used as substrate, it decides the mechanical properties and the steel shape and flatness.

6. Back paint film Epoxy, Modified PE. Back paint can sustain color in good condition and has good binding.