By Robin Harris.
Take two copies of the same manufactured CD from 1987 and subject to extreme heat and humidity in an environmental test chamber. Should turn out the same, right? No:
The one of the right is totally destroyed, while the one on the left is still playable. Why?

Commercially reproduced CDs the kind from major music labels are manufactured using a physical stamping on the plastic which is given a metallic coating to reflect the laser light a physical imprint on the media. Writable CDs and most writable DVDs and Blu-rays use a chemical organic dye layer that is inherently unstable and will often die within five years.
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