Something is eating my CD substrate

[Ron E]

Second, the disc is sputtered or metalized with aluminum on the top side where the data is.
Third, the metalized side is coated with a protective lacquer that is applied and distributed by spinning the disc at high speed.

The lacquer side is the most vulnerable side A scratch on the label side is much worse than a scratch on the read side. The thin layer of lacquer is the only protection for the aluminum layer. That is where teh exposure to air gets in.