Caustic cleaning products used on aluminum structures have the effect of producing

• A. Oxidation
• B. Corrosion
• C. Surface finish improvement
• D. Brittleness

Answer: (B)

Alkaline, caustic cleaners interact with aluminum in a way that breaks down its protective oxide film. Aluminum relies on this thin oxide layer to prevent corrosion, but strong caustics dissolve or destabilize that film. Once the oxide is removed, the metal itself reacts with the caustic solution, forming soluble aluminates and releasing hydrogen. This sequence allows widespread attack on the metal surface, leading to material loss and surface damage—the hallmark of corrosion. It’s not simply a benign oxidation or a surface polish effect; the cleaning agents actually promote corrosive attack on the aluminum structure. Brittleness isn’t the typical outcome of this interaction.