Pickling is a chemical treatment that removes impurities from the surface of metals. It’s often used on stainless steel to remove grease, oil, and weld heat tinted layers. Pickling can also be used on other metals, such as copper, aluminum alloys, and ferrous metals
Pickling is basically a cleaning process. Acid solutions are used to remove oxides from the surface of the metal. In addition, other substances on the surface of the metal will be removed, in whole or in part, and will therefore be present in the waste stream