Such as radiators, heat registers, and tin ceiling tiles
Prep: Clean unfinished metal with soap and water and a sponge; immediately blot dry if iron or steel. On already painted metal, use a wire brush to remove loose chips, then smooth uneven areas with 100-grit sandpaper before washing.
Coat: Use an oil-based primer on ferrous metals (those containing iron) to prevent rust, or a water-based metal primer on nonferrous surfaces. Opt for latex spray paint, one formulated to handle heat, where needed. Avoid drips by applying several thin coats, letting each coat dry in between.