[Table of Contents] [Search]


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: "Digital Dark Age"



Here's a bit more info from CD industry sources, my underlining: dt fletcher

Longevity & Liability: When a Good Disc Goes Bad
Successfully recording a disc is not enough to guarantee that the data that
you record will be accessible when you need it. This year has seen some
controversy over media longevity with inaccurate reporting on CD-R and CD-ROM
lifespan in both Business Week and U.S. News and World Report. Manufacturers
have generally estimated the longevity of CD-R media from 30 to 300 years.
These figures come from accelerated aging tests that try to predict future
stability by subjecting discs to specific levels of heat and light.
Besides this laboratory testing, some seat-of-the-pants testing has been done
and the results show that unlike Dracula, a CD-R disc's life is not threatened
by the rising sun. There have been assertions that cyanine CD-Rs will expire
if left dye-side-up on a desk near a window over a sunny weekend. Cyanine and
phthalocyanine discs have been exposed to two years' worth of sunlight shining
on their dye sides with no significant effect. While phthalocyanine does have
better light fastness, neither dye was degraded significantly.

Storing discs (and other media) at room temperature and away from sunlight is
just common sense--you don't need a professional archivist to tell you that.
While all media will degrade over time, the key to longevity is to make a top-
quality disc in the first place. The more errors that a disc contains when
it's written, the more susceptible it is to degradation. The key to low-error
discs is quality media. Good cyanine, phthalocyanine, and metal azo discs will
age well. The new silver/advanced phthalocyanine discs generally show a much
lower error rate upon recording than either cyanine, phthalocyanine, or metal
azo. However, no published advanced aging data is yet available on these
discs.


[Subject index] [Index for current month] [Table of Contents] [Search]