I discovered that if you are unfortunate enough to smear sunscreen lotion on your CD and let it dry, it will not wipe off. With water, with soap or anything. It also becomes unreadable.

A while ago, when Soft Cell's Tainted Love was re-released as a single, the CDs came in sporran-like leather pouches. Unfortunately, some chemical in the leather, some kind of ick from the tanning process, was wildly corrosive to the metal layer in the CD -- the metal layer was eaten away completely for about 3mm in from the disc rim, and there are macroscopic holes all over the surface, plus really bad tarnishing.

This was quite useful when we wanted to test HSX-109's behaviour on damaged CDs...

Peter