Below is a list of Aluminum Anodizing manufacturers from Milwaukee, Wisconsin. Aluminum anodizing is a surface hardening process in which electrolytic passivation is used to thicken the layer of oxide that naturally occurs on aluminum alloys. Used to increase corrosion and wear resistance, anodizing can be performed on a variety of metals, such as titanium anodizing; however, amongst anodisers aluminum is typically the metal of choice since it is naturally prone to corrosion due to alloying elements such as copper and iron.