PURPOSE: To prevent the stain of films formed on parts by vapor phase plating by forming films of silicon or a silicone compound on the plated parts.

CONSTITUTION: The surfaces of external parts are subjected to vapor phase plating such as vapor deposition, sputtering, ion plating or CVD. The resulting films are liable to stain. In order to eliminate this defect, the films are coated with silicon or a silicone compound. For example, the soln. of polydimethylsiloxane in isopropyl alcohol as a solvent is applied to the plated surfaces.