Etching and finishing products are used on patterned steels to remove material imperfections or modify shapes and designs. Traditionally, etching is a process that uses a strong acid or mordant to create a design on metal surfaces. Today etching products like theBS110 Ferric Chloride can be diluted with distilled water before using on materials like copper and stainless steel. This process usually happens after heat treating. Finishing items treat the exterior of metal products by the application of a thin layer. This can enhance material colors like theBC101 Copper Patina.