Aluminum surfaces are treated differently depending upon whether the metal is new or used. Paint must be able to "grip" or adhere to the surface onto which it is applied. Most aluminum surfaces have a layer of pure aluminum on the surface called alclad that protects the metal from corrosion. It is very smooth and not favorable to paint adhesion. Therefore the surface must be adequately prepared by cleaning and slightly roughening to guarantee primer adhesion. This is accomplished by using a conversion coating such as alodine. This chemical process creates a ceramic layer over the aluminum that coats the surface and provides tooth adhesion. Used aluminum must have any primers, paints, or corrosion removed. Paint strippers are used to remove old paint. After stripping old paint the corrosion should be completely eliminated. Use fine sandpaper, Scotch Brite pads, or aluminum wool. Never use steel wool or a steel brush. After the corrosion is removed the old aluminum should be acid etched. This is simply a process of washing the aluminum with a product such as Poly Fiber’s E-2310 Acid Etch diluted with water. An acid etch removes oil and light corrosion while etching or roughening the surface to provide a firm primer bond. The part is then thoroughly rinsed. Next wash the surface with E-2300 Conversion Coating that inhibits corrosion and further enhances primer adhesion. After this step the part is rinsed and allowed to completely dry. Once again, new aluminum surfaces need only be treated with a conversion coating.

After the aluminum (new or old) has been properly cleaned and treated, it is then primed. I would recommend using a two-part epoxy primer. An epoxy primer will insure corrosion protection and also provide a bonding surface for most topcoat paints. Very often, polyurethane topcoats will lift or wrinkle primers other than epoxies much as a paint stripper would do. A primer is necessary to provide a bond between the metal and the final topcoat paint. The primer coat should be applied according to the manufacturers directions. Usually, two light coats will be applied. Heavy coats should be avoided.