Why Does Metal Change Color in Water? Anodizing is an electrochemical process that enhances the natural oxide layer on a metal’s surface, most commonly aluminum, to improve durability, corrosion resistance, and appearance. In a simplified home or classroom version of anodizing, a solution of baking soda (sodium bicarbonate) and water can act as a mild electrolyte. When a voltage is applied using a power source, the aluminum object is connected to the positive terminal (anode), and another conduc