Process for forming inorganic skin film

A process for forming an inorganic skin film using a plating process selected from the group consisting of electrolytic plating, chemical vapor deposition, and sputtering, said inorganic skin film being formed of an aggregate of crystals, said aggregate including a plurality of (hhh) oriented crystals having a cubic crystal structure with their (hhh) planes (by Miller indices) oriented toward the surface of the skin film, at least some of said (hhh) oriented crystals being hexangular pyramid-shaped crystals or truncated hexangular pyramid-shaped crystals, said process comprising the steps of:

• controlling the output of a plating energy source to produce a pulse waveform such that said output is increased from a minimum value to reach a maximum value and then is reduced to said minimum value;
• and
• setting a ratio T.sub.on /T.sub.C of an output time T.sub.on to a cycle time T.sub.c within a range T.sub.ON /T.sub.C .ltoreq.0.45, wherein said output time T.sub.ON is from a start point of increasing said output to a start point of reducing said output, and said cycle time T.sub.C is the time required for one cycle from an increasing-start point to a next increasing-start point of said output.