CDs and DVDs Very Mortal
Published May 07, 2004
....Fred Byers, an information technology specialist at the National Institute of Standards and Technology, has looked at writeable CDs on behalf of government agencies, including the Library of Congress (news - web sites), that need to know how long their discs will last.
Manufacturers cite lifespans up to 100 years, but without a standardized test, it's very hard to evaluate their claims, Byers says. The worst part is that manufacturers frequently change the materials and manufacturing methods without notifying users.
"When you go to a store and buy a DVD-R, and this goes for CD-R as well, you really don't know what you're getting," he says. "If you buy a particular brand of disc, and then get the same disc and brand six months later, it can be very different."
This renders the frequently heard advice to buy name-brand discs for maximum longevity fairly moot, he says.
DVDs are a bit tougher than CDs in the sense that the data layer (or layers — some discs have two) is sandwiched in the middle of the disc between two layers of plastic. But this structure causes problems of its own, especially in early DVDs. The glue that holds the layers together can lose its grip, making the disc unreadable at least in parts.
....Rewriteable CDs and DVDs, as opposed to write-once discs, should not be used for long-term storage because they contain a heat-sensitive layer that decays much faster than the metal layers of other discs.
For maximum longevity, discs should be stored vertically and only be handled by the edges. Don't stick labels on them, and in the case of write-once CDs, don't write on them with anything but soft water-based or alcohol-based markers. [AP]
- CDs and DVDs Very Mortal
- Published: May 07, 2004
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- Section: Sci/Tech
- Filed Under: Music: News, Video: News
- Writer: Eric Olsen
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Comments on this articleComments
I've got CDs that are 17 years old and show absolutely no signs of this "rot" that he describes. I take great care of my discs, too, so I think that's the deciding factor. If you treat them like coasters, that's exactly what they will be one day. Treat them like you would vinyl and they'll last you forever. I never once believe the "indestructible" claims everyone else cites - we all know from the Titanic tragedy what happens when you boast how "indestructible" something is, don't we?
i have one CD that has become unplayable.
my copy of Marc Ribot's "Rootless Cosmopolitans" has more than just pinholes in it...the manufacturing process must have been bad because the hole are pretty big, like a couple of millimeters or so.
Tom: While poor treatment can clearly lead to problems, I don't think it will lead to the pinhole problems described. That seems simply to be a manufacturing defect, and I've got friends who treat their CDs very well indeed who have had one or two go south over time.
What we need are laser-readers for vinyl, so that the vinyl never wears down!
I've got a few CDs that wound up with holes in them because they unfortunately fell, were scraped, etc., and those have problems - but the problems are all due to those holes through the top layer.
I would urge anyone who uses those Case Logic notebook cases to be VERY careful - most of the CDs that I've had that had problems were stored in those cases. The problem with them is that while they protect the back side of the disc (non-label side) they don't protect the most fragile part, the layer under the label. The sleeves, as well as other CDs that face them on the opposite page rub against the thin coating over the aluminum reflective layer and slowly wear it away. Believe me - I have seen this on multiple discs, and I was able to confirm this several times. Those notebooks with sleeves are bad news for CDs. Had they a hard-cover that prevented flexing and crushing, they probably would have been fine. I lost some good discs that way.
Great points all - thanks!
can you tell me why these materials were chosen when first making dvds? i am doing a project for school about dvds and i would like to know so can you tell me i mean if you know
-thanks-
Tiffany, the clear material is polycarbonate, chosen probably because it's relatively strong, cheap, and light. The reflective layer is usually aluminum, but can be other metals like gold, too - it just needs to be reflective, so you'll see black discs being used as well (found especially in gaming devices.)
You may want to refer to the "freaks" over at CD Freaks for more info. Someone in the forums there will probably know a lot more about this subject than you're likely to find actually documented in layman's terms on the internet. Good luck!
thanks Tom, excellent info and suggestion
A great place to look for DVD related products and information. For all your dvd needs.
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Also, adverse changes in temperature in the area where you store CDs can cause them to deterioate, i believe.