You can transform an old-looking or mismatched radiator by finishing it with the appropriate type of paint. Before you begin, you will need to thoroughly clean the radiator to prevent problems with adhesion. In addition, you will need to apply the appropriate type of base coat, or you will end up with a finish that will eventually fail. Finally, you should select a paint capable of enduring relatively hot temperatures, or the finish may peel.
Turn off the radiator and allow it to cool.
Scrub the radiator with a water-based degreaser, using a coarse brush. Rinse the cleanser with wet rags. Wait 1 to 3 hours for the radiator to dry.
Cover the floor beneath the radiator with fabric dust sheets. Protect areas on or adjacent to the radiator you don't want painted with a low-tack painter's tape.
Coat the clean radiator with a galvanised metal etching primer, using a paintbrush, manufactured for use with water-based latex paints. Wait four hours for the primed radiator to dry.
Wash the brush with water.
Coat the primed radiator with a high-temperature paint. Apply paint to the radiator just as you did the primer. Wait two hours for the painted radiator to dry. Add another coat if the primer is showing through. Wait a full 24 hours before operating the radiator.
Although many argue that high-temperature paint is not necessary for painting radiators, it will remain durable for much longer than standard acrylic latex paints.
Never paint over an unprimed radiator, of the finish will fail. Do not use a plain oil-based or acrylic latex primer in place of an etching primer, or the paint will peel.