If you paint over rust without preparing the surface, recurrence will prove inevitable. To permanently seal rust, apply a particular type of rust-inhibiting primer. Don’t use ordinary latex or oil-based primers; instead, use an iron oxide primer. Once the it is primed, you can paint rusted metal with little trouble.

Tips & Warnings
• You may also use zinc chromate primer to seal rust; however, this primer is highly toxic.
• Be sure to scrape off as much rust as possible using a putty knife and/or wire brush.
• If the metal is slick, use a rust-inhibiting metal-etching primer.