Friday, January 18, 2002, 1:14:39 AM, Kenneth wrote:
KW> Don't know exactly what the problems are, but I have read and been told that
KW> photo image storage on CD-R can be adversely affected by "cheap" Discs. The
KW> Kodak Disc is the one to use for image storage.
KW> Can anyone elaborate/confirm this?
KW> Ken Waller
Well, some of my older "no-name" discs are already starting to show
signs of bubbles and other defects in the layer. Problem is even some
"name" discs are made by the same company doing the noname bad ones...
BTW, there is excellent CD-R faq that is REALLY big and comprehensive,
and there are questions and answers on that issue too... see:
www.cdrfaq.org; section #7 (media)
some interestng subjects:
Subject: [7-5] How long do CD-Rs and CD-RWs last?
Subject: [7-8] How do CD-Rs behave when microwaved?
Subject: [7-9] What can I do with CD-R discs that failed during writing?
Subject: [7-22] Is there really a fungus that eats CDs?
Quoted section 7-5 (I hope I won't offend the FAQ makers... for most
up-to-date, see the url)
CDRFAQ> There doesn't seem to be a clear answer for CD-RW. The rest of this
CDRFAQ> section applies to CD-R.
CDRFAQ> The manufacturers claim 75 years (cyanine dye, used in "green" discs), 100
CDRFAQ> years (phthalocyanine dye, used in "gold" discs), or even 200 years
CDRFAQ> ("advanced" phthalocyanine dye, used in "platinum" discs) once the disc has
CDRFAQ> been written. The shelf life of an unrecorded disc has been estimated at
CDRFAQ> between 5 and 10 years. There is no standard agreed-upon way to test discs
CDRFAQ> for lifetime viability. Accelerated aging tests have been done, but they
CDRFAQ> may not provide a meaningful analogue to real-world aging.
CDRFAQ> Exposing the disc to excessive heat, humidity, or to direct sunlight will
CDRFAQ> greatly reduce the lifetime. In general, CD-Rs are far less tolerant of
CDRFAQ> environmental conditions than pressed CDs, and should be treated with
CDRFAQ> greater care. The easiest way to make a CD-R unusable is to scratch the
CDRFAQ> top surface. Find a CD-R you don't want anymore, and try to scratch the
CDRFAQ> top (label side) with your fingernail, a ballpoint pen, a paper clip, and
CDRFAQ> anything else you have handy. The results may surprise you.
CDRFAQ> Keep them in a cool, dark, dry place, and they will probably live longer
CDRFAQ> than you do (emphasis on "probably"). Some newsgroup reports have
CDRFAQ> complained of discs becoming unreadable in as little as three years, but
CDRFAQ> without knowing how the discs were handled and stored such anecdotes are
CDRFAQ> useless. Try to keep a little perspective on the situation: a disc that
degrades very little over 100 years is useless if it can't be read in your
CDRFAQ> CD-ROM drive today.
CDRFAQ> One user reported that very inexpensive CD-Rs deteriorated in a mere six
CDRFAQ> weeks, despite careful storage. Some discs are better than others.
CDRFAQ> By some estimates, pressed CD-ROMs may only last for 10 to 25 years,
CDRFAQ> because the aluminum reflective layer starts to corrode after a while.
CDRFAQ> One user was told by Blaupunkt that CD-R discs shouldn't be left in car CD
CDRFAQ> players, because if it gets too hot in the car the CD-R will emit a gas that
CDRFAQ> can blind the laser optics. However, CD-Rs are constructed much the same
CDRFAQ> way and with mostly the same materials as pressed CDs, and the temperatures
CDRFAQ> required to cause such an emission from the materials that are exposed would
CDRFAQ> melt much of the car's interior. The dye layer is sealed into the disc,
CDRFAQ> and should not present any danger to drive optics even if overheated.
CDRFAQ> Even so, leaving a CD-R in a hot car isn't good for the disc, and will
CDRFAQ> probably shorten its effective life.
CDRFAQ> See also http://www.cd-info.com/CDIC/Technology/CD-R/Media/Longevity.html,
CDRFAQ> especially http://www.cd-info.com/CDIC/Industry/news/media-chronology.html
CDRFAQ> about some inaccurate reporting in the news media.
CDRFAQ> See "Do gold CD-R discs have better longevity than green discs?" on
CDRFAQ> http://www.mscience.com/faq53.html.
CDRFAQ> http://www.cdpage.com/dstuff/BobDana296.html has a very readable
CDRFAQ> description of CD-R media error testing that leaves you with a numb sense
CDRFAQ> of amazement that CD-Rs work at all. It also explains the errors that come
CDRFAQ> out of MSCDEX and what the dreaded E32 error means to a CD stamper. Highly
CDRFAQ> recommended.
HTH,
Good light,
Frantisek Vlcek
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