Anodizing aluminum: Difference between revisions

[[File:Sulfuric_acid_vs_sodium_bisulfate.png|right|thumb|350px|Samples comparing results of anodising aluminum with sulfuric acid against sodium bisulfate.]]]]Aluminum has an oxide barrier coating because of a reaction with the oxygen in air. By using an electrolytic process the metal can have additional protection. In general there are two types of barrier coatings. The first is a thin, hard coating that increases the hardness and insulation properties. The second is a porous cellular structure that allows a dye to fill in the cells and provides a decorative and protective coating - as used here. This is a variable process that may require some experiments to determine what is happening. Longer anodizing times, different concentrations and temperature, different grade of aluminum, different current draw or voltage, and patience are all helpful.<ref name="obs"/>