Patent No. U.S. 7,390,559 B2 PPG Industries has been granted a patent for a multilayer coating system comprised of a first, thermally cured coating, the first coating being produced from a first film forming resin having one or more thermally curable groups and one or more radiation curable groups; and a second, radiation cured coating comprised of a radiation cured resin; wherein at least some radiation curable groups in the first coating are bonded to at least some of the radiation cured resin of the second coating and the weight percent of radiation curable group(s) in the first coating is below that which is needed to render the first coating radiation curable.