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From: psk@ccice6.UUCP (Paul S. Kopel)
Newsgroups: net.audio
Subject: Deterioration of Compact Discs
Message-ID: <391@ccice6.UUCP>
Date: Fri, 11-Oct-85 13:29:51 EDT
Article-I.D.: ccice6.391
Posted: Fri Oct 11 13:29:51 1985
Date-Received: Mon, 14-Oct-85 05:40:32 EDT
Distribution: net
Organization: CCI Central Engineering, Rochester, NY
Lines: 25

The reflective, information carrying surface of a CD is covered by
a "protective layer" of transparent material through which the
scanning beam must pass.  Presumably, significant changes over time
in the physical and optical properties of the protective layer wil
affect a CD's reproducibility (i.e., it may crack, peel, change
color, become translucent or opaque, etc.).

I am unaware of any discussion of this matter.  Should it be a
concern, considering the cost of CD's and the claims of CD
indestructibility?  (If it has been discussed, can someone cite
a reference?)

Perhaps there are folks on the net with sufficient interest and
background in materials/organic chemistry (or friends with same)
to address the following:

	What is the material used for the protective coating;
	how do its physical and optical properties change over
	time in a "normal" environment?

	Are there (non-obvious) storage conditions which
	would hasten deterioration, either physical or optical?

	Are there methods of storage which would best prevent
	possible deterioration?