The zinc layer on the surface of galvanized steel can interfere with paint adhesion.
Remove the mill scale on hot rolled steel by abrasive blasting if it will be exposed to immersion or harsh chemicals.
CAST IRON has a rougher and more porous surface which can cause bubbles or blisters in the paint.
CONDITIONS and MATERIALS that often require extra surface preparation:
CAST IRON
GALVANIZED STEEL *
ALUMINUM
HOT ROLLED STEEL **
STAINLESS STEEL
PLASTICS
PICKLED STEEL
FIBERGLASS
* Excluding galvanneal
** Remove mill scale if exposed to harsh conditions
