Plating
When the groove, mono or stereo, has been cut in the lacquer, the engineer responsible for this examines it under a high-power microscope. He makes sure that the lacquer itself is without blemish, that there are no imperfections in its surface to mar the smooth walls of the groove, and that adjacent revolutions are separated by sufficiently wide lands of lacquer. He does not play this precious disc, because even the most sensitive of pickups would iron out its minute indentations. When he has satisfied himself that it is perfect, it is passed to the plating department.
The first step in the plating operation is to provide the surface of the lacquer with an electrically conductive deposit. It is coated with a fine film of silver (about five microns thick), and is then placed in an electrolytic bath and plated with nickel.
