Home Problems and solutions The paint has peeled off, and the iron has been exposed. Metal CausesThe surface was not properly prepared (e.g., rust, oil residues were not adequately removed, or the surface was not sanded).The wrong primer was applied.The primed surface was not dry when the paint was applied. SolutionRemove the problematic coating by sanding or using a solvent.Apply one coat of RUST BLOCKER AQUA and two coats of HARD DUKO or HARD & GLOSS.