Due to the high content of alloying elements such as Si, Cu, Fe, which are not anodic, the formation of a continuous and sufficiently thick oxide layer is demanding and requires special procedures. This is especially true for die cast parts. Europur has developed a special procedure for hard anodic oxidation of such materials, in which layer thicknesses is of min. 20 µm and in some cases 30 µm. These layers are also black-dyeable, achieving unification of otherwise quite uneven shades of the product.