Removing primer from metal can be either easy or difficult depending on the type of primer with which you're working and the methods you use. Metal is a poor candidate for adhesion, so ordinary acrylic and latex primers don't bond well and generally come free with the help of the right scraping tools. However, if the metal is coated with an acidic metal-etching primer, scraping is fruitless. To free this type of primer, use a stripping solvent to dissolve the coating. Employ the correct strategy based on the type of primer with which you're working or you may end up frustrated.
Things You'll Need
Metallic putty knife
Long rubber gloves
Plastic masking sheeting
Canvas drop cloths
Paint stripping solvent
Natural-bristle paintbrush, 2- to 4-inch
Water-based degreasing cleanser
Water hose or wet rags
Scrape and sand off as much primer from the metal as possible using a metallic putty knife, wire brush and 60-grit sandpaper. You are finished with the removal at this point if you are able to remove all the acrylic or latex paint.
Put on a protective respirator and a pair of long rubber gloves if primer remains.
Spread plastic masking sheeting underneath the metal. Place absorbent canvas drop cloths over the sheeting.
Apply stripping solvent to the remaining primer, only using a natural-bristle brush. Prevent rapid evaporation by covering the metal with more plastic sheeting.
Let the solvent loosen the primer for five minutes.
Remove the sheeting and scrape the loosened primer from the metal using the metallic putty knife, wire brush and 60-grit sandpaper. Repeat this procedure as necessary until the metal is free from primer.
Scrub the metal with a degreaser, using steel wool. Rinse the metal with water from a hose or wet rags.
You do not need to use a stripping solvent if you are working with acrylic or latex primer.