Hard anodizing is a newer method in the electrochemical oxidation of aluminum and aluminum alloys. It is obtained under the condition of cooling dilute sulfuric acid oxidation solution to obtain high hardness and thick film oxide film. This process is called hard anodizing or thick film anodizing, or simply called "hard oxidation". Eco-Friendly Bamboo Fibre Coffee Cup,Eco-Friendly Coffee Cup,Eco-Friendly Bread Box,Eco-Friendly Lunch Box PERFECTS ENTERPRISE LIMITED , https://www.chibelco.com