Compact disc bronzing

CD bronzing seems to occur mostly with audio CDs manufactured by Philips and Dupont Optical (PDO) at its plant in Blackburn, Lancashire, UK, between the years 1988 and 1993.

A similar, if considerably less widespread problem occurred with discs manufactured by Optical Media Storage (Opti.Me.S) in Italy.

[4] A combination of the two factors seems likely because, as Barbara Hirsch of the University of California points out, the oxidation could only have occurred if the protective lacquer did not seal the metal film and substrate well enough.

[2] There are also isolated reports of CD discolouring with discs from other pressing plants, but these do not seem to be as widespread and may be due to reasons other than the manufacturing error that occurred at PDO.

However, storage conditions certainly seem to contribute to the speed of the decay, as some bronzed CDs were already reported as unreadable in the mid-1990s, whereas others were still playable as recently as 2012.