RE: [AV Media Matters] CD-R Audio disc longevity

[Charles Repka <Charles.P.Repka@abc.com>]

There have been a numbers of posts on this subject on this forum in the
past.  Check the archives and you may find something of interest to you
there, especially cross references to postings on other forums.  The is a
clearing house of some kind that has posted data in the past but the data
I've seen is several years old and probably does not apply to current
product.  Manufacturers constantly changing and modifying their product and
manufacturing process.  For example. CD-R's with a gold reflective layer
have virtually disappeared, to be replaced by silver.  And I here rumors
that everyone is looking furiously to find a way to use aluminum as a
reflective surface for CD-R's.  Gold does not corrodes the way silver does
and silver backed discs need better protective coatings and edge seal.
Another problem is CD-R manufacturers keep appearing ( and disappearing)
like mushrooms.  Will the 20 cent(retail) disc made somewhere in SE Asia be
as good and the best Kodak, or Taiyo Yuden or Mitsui can make.  Maybe, on a
given production run.

At best, the life numbers given by manufacturers and the independent test
agencies are a calculated guess.  The test are done by recording a bunch of
discs from or different manufacturers and then making error rate
measurements.  the discs are then subjected to a specified number of hours
of elevated heat and humidity and the error rates remeasured.  From this
data, they somehow calculate an expected life of 30 years ( or 50 years, or
100 years, take your pick)  I have seen no data on discs tested for exposure
to ozone, sulfur dioxide and nitrogen oxides, all common air pollutants in
large urban environments.  And a lot depends how the  disc is stored and
handled.  A disc stored in a sealed container back filled with argon will
obviously last a lot longer than one stored on the studio shelf and used as
an occasional Frisbee.

I would take any longevity claims from a manufacturer with a large grain of
salt and in my personal opinion, if you want a piece of information to last
a really long time, carve it into a block of granite. :-)

Charles Repka

>-----Original Message-----
>From: jmcbride@jaguar.middlebury.edu
>[mailto:jmcbride@jaguar.middlebury.edu]
>Sent: Wednesday, March 07, 2001 11:01 AM
>To: AV Media Matters
>Subject: [AV Media Matters] CD-R Audio disc longevity
>
>
>I've been reading this list with interest regarding the
>permanence of CD-Rs.
>Is there any information about which brands of blank CD-R Audio discs are
>the most durable and least likely to degrade over time? My presumption is
>that they are made of the same materials as the plain, blank CD-Rs.
>
>Jerry McBride, Music Librarian       Music Library, Center
>for the Arts
>Jerry.McBride@middlebury.edu    Middlebury College
>(802) 443-5217                             72 Porter Field Road
>Fax: (802) 443-2057                     Middlebury, VT 05753-6177
>http://www.middlebury.edu/~lib/musiclib/musiclib.html