Body finishing: Order consensus???

[rotorwrench]

The right mix of aqueous cleaner, phosphoric acid, & phosphate or zinc salts etch solution does more than remove smut and etch the surface of the mild steel. It converts the surface to an inert zinc phosphate which is a lot less apt to corrode. Manganese is also used in some mixtures. Any corrosion that the blasting didn't get off is converted to iron phosphate which is also inert. Manufacturers refer to it as a conversion coat and use it to passivate the surface with phosphates just prior to paint or pickling. Blasting gets most of the corrosion but there is always some left down in the grain of the metal.