the Washington Post

may 14, 2004



    CD and DVD Owners Finding Techno-Rot

    By Peter Svensson
the Associated Press

    Dan Koster was unpacking some of his more than 2,000 CDs after a move
when he noticed something strange. Some of the discs, which he always took
good care of, wouldn't play properly.

    Koster, a Web and graphic designer for Queens University of Charlotte,
N.C., took one that was skipping pretty badly and held it up to the light.

    "I was kind of shocked to see a constellation of pinpricks, little
points where the light was coming through the aluminum layer," he says.

    His collection was suffering from "CD rot," a gradual deterioration of
the data-carrying layer. It's not known for sure how common the blight is,
but it's just one of a number of reasons that optical discs, including
DVDs, may be a lot less long-lived than first thought.

    "We were all told that CDs were well-nigh indestructible when they
were introduced in the mid-'80s," Koster says. "Companies used that in
part to justify the higher price of CDs as well."

    He went through his collection and found that 15 percent to 20 percent
of the discs, most of which were produced in the '80s, were "rotted" to
some extent.

    The rotting can be due to poor manufacturing, according to Jerry
Hartke, who runs Media Sciences Inc., a Marlborough, Mass., laboratory
that tests CDs.

    The aluminum layer that reflects the light of the player's laser is
separated from the CD label by a thin layer of lacquer. If the
manufacturer applied the lacquer improperly, air can penetrate to oxidize
the aluminum, eating it up much like iron rusts in air.

    But in Hartke's view, it's more common that discs are rendered
unreadable by poor handling by the owner.

    "If people treat these discs rather harshly, or stack them, or allow
them to rub against each other, this very fragile protective layer can be
disturbed, allowing the atmosphere to interact with that aluminum," he
says.

    Part of the problem is that most people believe it's the clear
underside of the CD that is fragile, when in fact it's the side with the
label. Scratches on the underside have to be fairly deep to cause
skipping, while scratches on the top can easily penetrate to the aluminum
layer. Even the pressure of a pen on the label side can dent the aluminum,
rendering the CD unreadable.

    Koster has taken to copying his CDs on his computer to extend the life
of the recordings. Unfortunately, it's not easy to figure out how long
those recordable CDs will work.

    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, that
need to know how long their discs will last.

    Manufacturers cite life spans 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.

    Users that bend a DVD to remove it from a hard-gripping case are
practically begging for this problem, because flexing the disc puts strain
on the glue.

    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 be
handled only 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.

    Also, like wine, discs should be stored in a cool, dry place. Koster's
friend Mark Irons, of Corvallis, Ore., stored his CD collection in a cabin
heated by a wood-burning stove. The temperature would range between 40
degrees and 70 degrees in the space of a few hours. Now, the data layer of
some of his CDs looks as if it's being eaten from the outside.

    Irons is still pretty happy with CD technology, since it beats vinyl
LPs and tape for longevity. Now that he's moved his discs to an apartment
with a more stable temperature, he's noticed that the decay has slowed.

    "I'm hoping they'll hold out till that next medium gets popular, and
everyone gets to buy everything over again," he says.


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