• Type II anodizing: sulfuric acid anodizing. This is the standard anodizing at Xometry, and it can be either neutral or colored, which is often chosen as aesthetic post-treatment
• Type III anodizing: hard anodizing. The anodized layer is thicker, resulting in better resistance to wear and external agents, and increasing surface hardness. But this type of anodizing alters the natural color of aluminum and the choice of colors is more restricted.

A more detailed comparison of these types of anodizing is given in this article: https://xometry.pro/fr/articles/anodisation-aluminium/ The aluminum alloys most favorable for a type II anodizing, for a homogeneous aesthetic rendering are the 6000 class alloys, in particular 6061 and 6082. They are also particularly indicated for a hard anodizing, type III. The 5000 class alloys (ex: 5083) and 7000 class (ex: 7075) can also be anodized in type II or III but the aesthetic rendering will be more uncertain, this will depend on the dimensions and which particular alloy. For example, zinc alloys, class 7000, will take on a slightly yellow-brown hue via this treatment.