Before you attempt to paint a metal fireplace, keep these factors in mind. First, because metallic surfaces are nonporous, you must abrade them to promote adequate paint adhesion. Unfortunately, metal's durability makes friction-based abrasion methods impossible. This means you'll need to apply a special kind of primer to etch the metal before you paint. In addition, because fireplaces generate a lot of heat, use a specific kind of paint capable of withstanding high temperatures.
Scrub the fireplace with a degreaser, using a coarse brush. Rinse the metal with wet rags. Allow the surface to dry.
Apply painter's tape to portions of the fireplace you want left unpainted. Cover larger areas below the fireplace with dropcloths.
Apply a light coat of galvanized metal-etching primer to the metal fireplace, using a 3- to 4-inch latex paintbrush. Apply only a light coat. Do not over-apply as this may lead to runs and brushstrokes in the final finish. Allow the primer to dry and cure for four hours.
Wash the paintbrush with water, and allow it to dry thoroughly.
Apply two light coats of epoxy appliance paint to the primed fireplace, using the paintbrush. Apply the epoxy paint the same way you did the primer. Allow two hours of dry time between coats.