[ziari]

The polycarbonate substrate could degrade due to temperature, humidity, exposure to sunlight, and other environmental variables. These are concerns for institutions with large CD-based archives (e.g., Library of Congress). [1]

In practice, though, it's far more likely that the the disc will get corrupted from small scratches.

[1] https://www.npr.org/sections/alltechconsidered/2014/08/18/34...

[tarcyanm]

I have taken several CDs (mainly my Dad's, not my own) from unusably scratched to relatively pristine. The really bad cases need fine grit sandpaper (wet!) followed by plastic polishes. I generally start with Meguiar's plastic polish and work my way to Radtech Ice Creme. In my own collection I have CDs that are around 30 years old and are error-free. I'm not interested in formats or services that won't last at least as long or can't be backed up to my own NAS (nor am I interested in anything less than Red Book quality).

[npongratz]

And don't forget about the fungus that eats CDs!

https://www.nature.com/news/2001/010628/full/news010628-11.h...