...

The laser of your CD-R/CD-RW drive heats the dye to a temperature of about 200° C, irreversibly melting a pitted pattern into the recording layer. A plastic layer alongside the dye expands into the newly available space, creating a pit pattern similar to that of a conventional CD. Your CD player reads this highly reflective pattern for playback. Because the plastic layer melts into the dye layer to set the pattern, CD-R discs cannot be re-recorded.

Layers of CD-R

The following diagram provides a cross-section of a CD-R:

Image Added