Partial restoration of an anodized coating damaged in service is achieved by which method?

• A. Chemical surface treatment
• B. Re-anodizing
• C. Painting
• D. Polishing

Answer: (A)

Restoring the protective oxide on anodized aluminum after damage is best done by a chemical surface treatment. This approach reconditions and seals the damaged area of the porous anodic film, often through sealing or applying a surface conditioner that reduces porosity and re-passivates the layer. By treating the existing coating chemically, you regain corrosion protection in the affected spot without removing or completely rebuilding the oxide elsewhere, which keeps downtime shorter and avoids disrupting the surrounding intact coating.

Re-anodizing would require removing the damaged area and re-forming the oxide, which is more invasive and difficult to localize. Painting introduces a separate layer that doesn’t restore the native anodic protection and can trap moisture or peel under varying conditions. Polishing removes more of the coating, exposing the underlying metal and compromising protection rather than restoring it.