Aluminium is the most common metal on earth and it exists in many different alloys, grades of hardness and quality. Most are suitable for the various decorative finishes. Since Aluminum does oxidize, albeit very slowly, a protective coating is necessary. An ingot is a piece of relatively pure material, usually metal, that is cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products.Aluminum can also be dyed successfully with organic dyes or coated with transparent colored coatings.