The process is called anodising because the part to be
treated forms the anode electrode of an electrolytic cell. Anodising
increases resistance to corrosion and wear, and provides better adhesion
for paint primers and glues than bare metal does. Anodic films can also
be used for a number of cosmetic effects, either with thick porous
coatings that can absorb dyes or with thin transparent coatings that add
interference effects to reflected light.