Chromating is effective for treating almost all metals, most often zinc and aluminum. By reacting the hexavalent chromium solution with the metal, the chromium is reduced, the metal surface oxidized, and the insoluble chromium-metal compound formed. Due to the toxicity of hexavalent chromium, it is replaced today by other methods, for example in the case of aluminum pretreatment, so-called titanation and also trivalent chromate.