Posted by Risto Lankinen on 09/02/05 11:15

"Zombie Wolf" <zmbwf@gwi.net> wrote in message
news:cf6dnZKRmO7OsYXeRVn-tw@giganews.com...
> Well, I have quite a few CD's that have been around here for years. To me,
> there are only two places for a CD or DVD: In the machine or in the case.
> But , TLC notwithstanding, some of them have failed. The phenomenon is
> called "edge rot'. This is a condition where the edge of the media was not
> properly sealed when it was made, and the air gets into the data layer
(the
> metal coating) of the CD, and it simply disappears.When it gets bad
enough,
> you can actually see it around the edges of the CD.

I have a collection of ~1400 CD's, and the average age of individual
CD's is, I'm guessing, ~8 years. From the sample of this size, I've lost
exactly two thru media degradation while being appropriately stored.

The first one is a 3'' CD single manufactured in UK in 1994 and found to
be damaged sometime between 1996-1999. The disc had thousands of
tiny spots of rust in the reflective layer, but had no visible flaws in the
edge
sealing. I tend to suspect manufacturing error (dust or humidity sealed
_in_
in the factory?).

The second one is a regular 5'' CD album manufactured in France in 1985
and found to be damaged some time between 2000-2002. The disc had
a fingerprint on the _label_side_ which had burnt its way thru the
protective
layer onto the reflective layer. The reflective layer now has a permanently
embossed fingerprint shape on it!

Based on these figures, CD format seems to have greater than 5000 year
MTBF when in storage, which is remarkably good. Of course, YMMV.

- Risto -

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