Surface defects can arise during handling, machining, or finishing.

Defect Cause Solution
Scratches and Dents Poor handling or inadequate protective measures. Use protective films during transport and fabrication.
Porosity Incomplete removal of oxides or contaminants during welding. Clean thoroughly before welding and ensure proper shielding gas coverage.
Discoloration or Staining Improper cleaning, exposure to moisture, or contamination. Use anodizing or powder coating, and store aluminium in a dry, controlled environment.
Oxidation Natural reaction of aluminium with air to form oxide layers. While this is natural, it can be controlled with surface treatments like anodizing or painting.