A glass master is an exact reproduction of the original master, a photo sensitive layer applied to the “glass” is etched by a powerful laser before being “fixed” by a chemical process.
This glass master is then processed through a bath in which an electrical charge is applied to build up a layer of various metals. Once this layer is around 300 microns thick (0.3 mm) the process is stopped and this layer is removed from the glass master and trimmed.
It is this “stamper” (a mirror of the raw data) that is used in the presses that heats (at great temperature) the raw material of the disc – polycarbonate.
The glass master in an essential part of the production process, once made it is stored in readiness to produce other “stampers” should a re-press be required or more than 20,000 discs produced.
CD Duplication by HDC Media
