What can be used to repair the anodized surface of an aluminum alloy part?

• A. A chemical conversion coating such as Alodine.
• B. A rough sanded finish.
• C. A coat of ordinary paint directly on bare metal.
• D. Applying epoxy resin.

Answer: (A)

When repairing an anodized aluminum surface, a chemical conversion coating such as Alodine is the appropriate method because it chemically bonds to the aluminum oxide layer and forms a protective film that seals the pores created by the anodizing. This restores corrosion resistance and provides an excellent, uniform base for subsequent primers or paints.

Rough sanding would remove or damage the anodized layer, leaving the metal exposed and inconsistently prepared. Painting directly on bare metal doesn’t address the oxide layer or its pores and typically leads to poor adhesion and corrosion protection. Epoxy resin alone adds a coating but doesn’t restore the anodized surface or its protective properties, and can create incompatibilities with future finishes.