Abstract: A method for inhibiting the formation of stains, especailly water stains, on the exterior surface of aluminum alloy products. The method entails contacting the exterior surfaces of these products, particularly sheet or plate products, extrusions and/or forgings made from 5000 or 6000 Series aluminum alloys, with an organophosphonic or organophosphinic acid-derived material. Preferably, liquid forms of this material are added to an alcohol or water-based carrier solution, then sprayed, dipped, painted or rolled onto the surfaces of flat sheet or plate products to enhance their brightness. Other more complex shapes may be dipped into material baths.