Aluminum is a relatively non-noble metal. This negative property necessarily leads to a slight oxidability. This is why aluminum is very quickly covered with a layer of natural oxide. Initially, it only has a thickness of a few hundredths of a micron, then its size increases with time to form a topcoat which id capable of protecting the metal below it . Therefore, the greatest possible protective effect is aimed especially at external application. Unlike other protective measures such as paint coats or lacquering, anodizing can enhance the metallic character of aluminum.