Abstract: The present application relates to a method for enhancing metal corrosion resistance of a metal deposited on a substrate, the method comprises contacting the metal coated substrate with a treating composition comprising metal oxide nano-particles. Furthermore, the present application relates to a method for making a mirror comprising a substrate having a metal coated thereon, wherein the method comprises contacting the metal coated substrate with a treating composition comprising metal oxide nano-particles. Preferably, the metal oxide nano-particles are selected from one or more oxides of zinc, iridium, tin, aluminum, cerium, chromium, vanadium, titanium, iron, indium, copper, gold, palladium, platinum, manganese, cobalt, nickel, zirconium, molybdenum, rhodium, silver, indium, wolfram, iridium, lead, bismuth, samarium, erbium, or mixtures of these materials. In addition, the present application relates to the products obtainable by these methods.