To: WSFAlist at keithlynch.net
Date: Sun, 14 Apr 2002 02:06:02 -0400
Subject: [WSFA] CDs, CD-Rs, and CD-RWs
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

After checking at www.howstuffworks.com, I found that Keith was right
about
CD-Rs having a chemical component.  There is a dye layer between the
plastic disk and the aluminum layer.  The dye is permanently changed by
the intense IR used to burn the data, but is also sensitive to light, and
the article says that CD-Rs will deteriorate if exposed to sunlight.
CD-RWs, on the other hand, have the data burned in using a spot
temperature of 600 degrees C, and are erased using a spot temperature of
200 degrees C, so it seems that CD-RWs might be more durable than CD-Rs,
so long as they stay much cooler than 200 degrees C.  Regular CDs would
also be more robust than CD-Rs, since the data is encoded using pits in
the plastic disk.  Also, it seems that CD-Rs might be degraded just by
being read repeatedly.

Ron Kean

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