The adhesion to plastic substrates (112) of thick layers of functional metals (116) having an oxide heat of formation that is greater than -40,000 calories/gram atom of metal, such as silver, copper, gold, and the like, is improved if a thin layer of a metal having an oxide heat of formation of less than -50,000 calories/gram atom of metal is present as an adhesion-promoting primer layer metal has a melting point greater than 1100 °C, it should be present as the metal or as a substoichiometric oxide. When the primer layer metal (114) has a melting point less than 1100 °C, it may be present as the metal, as a substoichiometric oxide, or as a full stoichiometric oxide. Processes for preparing these materials using sputter-depositing and reflectors incorporating these materials are also disclosed.