No matter the coating process: The better the pretreatment, the better the adhesion. This is why the parts to be coated must be prepared by sandblasting and degreasing in suitable solvents prior to coating. This step removes impurities and prepares the surface of the metal for optimal adhesion.
Corundum or marcasite should be used as the blasting agent. Spherical blasting agents like glass pearls are not suitable because they do not roughen the surface. Blasted grease- and oil-free metal parts corrode very quickly, and should therefore be processed as soon as possible after blasting.
A primer for improving adhesion is not required. Zinc and iron phosphatising should also be avoided. These conversion layers begin to disintegrate above 200 °C and generate a separating layer, which impairs adhesion.