reanodized

Reanodized is a term used to describe the process of applying a new anodic oxide coating to aluminum alloys after the previous anodized layer has been damaged, degraded, or is no longer satisfactory. The reapplication aims to restore corrosion resistance, wear resistance, and surface appearance, and may also enable color restoration or change.

The process generally begins with cleaning and evaluation of the existing coating. If the old anodic layer is intact but worn, some operations may simply reanodize by renewing the oxide; if corrosion or damage is severe, the part may be stripped of the old oxide before reanodizing. The part is then placed in an electrolytic bath (most commonly sulfuric acid for conventional anodizing, or oxalic acid for special cases) with controlled voltage or current to form a new oxide layer on the aluminum surface. The oxide thickness is chosen to achieve the desired properties (cosmetic color, wear resistance). After anodizing, the surface may be dyed to achieve color and is typically sealed to reduce porosity and improve corrosion resistance.

Applications include architectural extrusions, aerospace components, automotive parts, and consumer electronics housings. Reanodizing allows color matching and refreshing of surfaces without replacing parts. It can extend service life and maintain performance, though it may not fully restore a surface damaged beyond the substrate's integrity or reproduce the exact original coating thickness.

Considerations include cost, process control, alloy compatibility, and environmental concerns due to acid baths and effluents. Surface porosity after sealing is a factor for corrosion resistance; reanodized layers can be thicker in hard anodizing for improved wear resistance but require different processing conditions.