A METHOD FOR ELECTROLYTICALLY PASSIVATING A SURFACE OF SILVER, SILVER ALLOY, GOLD, OR GOLD ALLOY

The present invention relates to a method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy, the method comprising the steps of(i) providing a substrate comprising said surface,(ii) providing an aqueous passivation solution comprisingtrivalent chromium ions, andone or more than one species of carboxylic acid residue anions,(iii) contacting the substrate with said passivation solution and passing an electrical current between the substrate as a cathode and an anode such that a passivation layer is electrolytically deposited onto said surface,wherein the trivalent chromium ions with respect to all species of carboxylic acid residue anions form a molar ratio in the range from 1:10 to 1:400.