Chemical coloring of metals is the process of changing the color of metal surfaces with different chemical solutions. The chemical coloring of metals can be split into two types: * electroplating - coating the metal surface with another metal using electrolysis. * patination - chemically reacting the metal surface to form a colored oxide or salt. Chemically coloring a metal is distinct from simply coating it using a method such as gilding or mercury silvering, because chemical coloring involves a chemical reaction, whereas simple coating does not.