Protective coatings for improved tarnish resistance in metal foils

The present invention relates to a composite article and a method for treating metal foil to prevent or avoid tarnish of the surface of the metal foil. In particular, the present invention relates to a method of forming the composite article including treating the metal foil with an inert silane, titanate or zirconate compound to form a protective film which improves the metal foil's resistance to tarnish when the metal foil is attached or held adjacent to a metal sheet comprising a different metal. In one embodiment, the present invention relates to a composite article, comprising a metal foil having a first side and a second side; a protective film of at least one inert silane, titanate or zirconate overlying the first side of the metal foil; and a metal sheet having a first side and a second side, the first side overlying the protective film. In another embodiment, the present invention relates to a method of increasing tarnish resistance of metal foil comprising contacting the metal foil with an inert silane, titanate or zirconate compound to form a protective film having a thickness from about 0.001 microns to about 1 micron on a surface of the metal foil; and attaching the foil to a metal sheet.