Three ways of surface treatment can be adopted: galvanizing, painting and untreated, of which hot-dip galvanizing is recommended Hot-dip galvanizing is a form of galvanization.It is the process of coating steel grating with a thin zinc layer, by passing the metal through a molten bath of zinc Mean coating thickness is 70 um when steel bars range from 3mm to 5mm in thickness.Painting is also a good way to get Surface Protective Film. paint types, coatingthickness depend on customer' a choice.