Though aluminum does not rust, it chemically reacts with oxygen in the environment to produce oxidation, a thin, whitish coat that helps to protect the metal surface. If the surface is damaged, however, this oxidation can continue to degrade into the metal surfaces, causing pits and eventual structural cracking. Oxidation can then loosen the paint on the surface of the aluminum, working its way gradually under larger and larger areas.
Aluminum does not naturally hold paint well. The surface of the metal must be treated to increase its adherence properties. First, remove the damaged layer of paint from the metal with paint remover or by thoroughly sanding the surface. Pitting from oxidation should be removed with a grinder to create an even surface. Roughing up the surface of the aluminum will then help it to hold onto paint firmly, according to the Rustoleum website. There are special primers that react chemically with the aluminum surface to allow the metal to hold the topcoat paint.
Powder Coating Aluminum
Powder coating is another option for dealing with peeling on aluminum handrails. A powder coat finish, composed of electrostatically-charged pigment and a special resin, is applied to the metal. It is then baked onto the metal surface at high temperatures and allowed to cure, according to the Powder Coating Institute site. This gives aluminum railings a hard, even finish that will last for years. Though more expensive than ordinary paint, powder coating generally does not have peeling problems. Cleaning powder-coated railings is done with mild detergent and water.
Correcting Peeling Paint Problems
To correct peeling paint problems on aluminum handrails, first sand off the old finish as much as possible. The sanding itself will help the paint to adhere to the aluminum. Dust off all sanding grit and wash the surface carefully. Allow the surface to dry. Then apply an aluminum primer over the area and repaint to the desired color. Consult with your local powder coating contractor about railings with damaged paint. Generally, damaged paint surfaces are first sandblasted off the metal before re-finishing with the powder coat process.