I was reading a thread in the Restoration Society forum about the effect of magnetism on cart data and bit-rot in various media, and it got me curious about the lifespan of CD-ROMs. I've read that CDs supposedly begin to degrade after 35 to 100 years (although they should be readable for a longer period). I was wondering if anybody knows what the mechanism of degradation is, as I am assuming that this includes even properly stored CD media.