If you would like to paint a cast iron baseboard, consider an important point about adhesion before you touch a brush. Unlike porous wood trim, cast iron baseboards are poorly suited for adhesion. Treat the cast iron with an acidic base coat, formulated to etch durable galvanized metal surfaces. Once the baseboard is properly treated, it will take a painted finish. Choose a durable paint that will resist nicks and stains. Use a particular type of paintbrush, or the cast iron may dry flawed.
Wash the cast iron baseboard with a water-based soap, using a sponge. Use rags and towels to rinse and dry the baseboard.
Apply masking paper to the floor beneath the cast iron baseboard, using painter's tape. Apply tape to the portion of the wall immediately above the baseboard.
Coat the cast iron baseboard with metal etching primer, using a soft-bristled polyester brush. Brush horizontally, applying gentle pressure. Wait three hours before painting.
Wash the soft-bristled polyester brush.
Coat the cast iron baseboard with gloss latex paint, using the clean soft-bristled polyester brush. Brush horizontally, applying gentle pressure. Allow three hours of dry time.
Do not paint an unprimed cast iron baseboard, or the paint will peel.
Do not treat cast iron baseboards with acrylic or latex primers, or the finish will flake.
Don't use flat or satin latex paint on a baseboard, as it may not remain durable.