Which statement best describes the purpose of Alodine coating on aluminum?

• A. A slightly rough surface
• B. Increased corrosion resistance
• C. A smooth painting surface
• D. Relieved surface stresses

Answer: (B)

Alodine is a chromate conversion coating that forms a protective chemical film on aluminum. The main purpose is to increase corrosion resistance by creating a barrier that reduces aluminum’s tendency to oxidize in moist or salty environments. It also helps paint adhere, but corrosion protection is the primary reason it’s used. It isn’t intended to roughen the surface, create a smooth painting surface, or relieve residual stresses.