Moisture is the main thing, but not the only thing. Even dry old cloth can rot from the inside out, thomas_black81. The fibers just break down over time. I've seen dry, stored canvas tents from the 90s just crumble when you touch them.

Ugh, that's brutal. Always check the price box too, reprints usually have a barcode or a modern logo.

Once heard about a guy who found a family of raccoons in his attic after ignoring some scratches. Cost him a fortune to remove them safely.