SpectraDisc of Providence, Rhode Island, has won a basic patent (US 6343063) on self-destructing DVDs. The idea is that people renting the DVD will not need to return it to the store. The disc is doped with hygroscopic salts such as magnesium chloride, and its surface is covered with a peel-off barrier, like a record label.
To play the disc you have to remove the barrier. The salts then start to pick up moisture from the air, producing a corrosive mix that begins to eat away the aluminium layer of the disc that holds the data. So the disc will…
