Whats the difference between CD-R, CD-RW and pressed (commercial) discs?
There are three technologies involved: CD-R uses a dye to record information; it can be written only once. CD-RW uses the change of state of an alloy and can be erased and rewritten. These are discussed elsewhere in this primer. A pressed disc is, in fact, pressed. The information of the audio stream and the TOC is prepared by a special program to create a glass master. That master is used to make one or more metal stampers. A stamper is pressed into a fluid plastic layer of the blank disc to impress the information. Once set, that disc is given an aluminum coat from which the read laser is reflected. At any point in that process, a speck of dust means a flaw in reproduction, so pressing requires a clean room and special operations to avoid contamination. Fortunately, CD-R and CD-RW are more tolerant and small amounts of contamination are seldom detected. Errors in digital recording? Is that for real? Unfortunately, it is. CDs of all sorts are read by analogue mechanisms and digitized
