At 04:20 PM 3/5/99 -0500, Tom Millar <tmillar@utkux.utcc.utk.edu> wrote:
quoted 2 lines The CDR is not as durable as everybody wants to make it seem.
>The CDR is not as durable as everybody wants to make it seem.
>I know of CDRs, MDs, and lots of other writable optical media that have
become
quoted 2 lines corrupted beyond recognition with just a year or two of (admittedly heavy)
>corrupted beyond recognition with just a year or two of (admittedly heavy)
>use.
I've read many posts like this by people with an axe to grind. Press them
for details, and you find out that they're based on anecdotes - it
happened to a friend of a friend, or they read it on rec.pro.audio, or
whatever. Have you personally experienced optical CDR failures, or were
they caused by scratches to the dye (label) side?
quoted 4 lines The fact is that any media that can be written and rewritten upon with
>The fact is that any media that can be written and rewritten upon with
>such common wavelengths (light, esp. visible colors) is going to be
>tremendously susceptible to damage merely by being played. Every time you run
>a laser, even the wussy ones in a portable CD player, over a CDR's
surface, it
quoted 1 line has a chance of causing a sector to dye itself.
>has a chance of causing a sector to dye itself.
This is like saying that, because you get sunburned in sunlight, then each
time you expose your skin to a 100W lightbulb, you run the risk of getting
sunburned. The write laser in a CDRecorder is a lot higher powered than
the read laser in a CD player - something like an order of magnitude.
Like your skin, it takes a certain level of light of a certain wavelength
for a certain duration to change CDR dye. Those conditions are not
present in a CD player.
But don't take my word for it, it's fairly easy to disprove, if you have a
CD player that tracks the disc in PAUSE mode (hint: it always starts
immediately after pause and you can hear a faint whirring. another hint:
most CDRom drives shut off after an inactivity timeout, so they won't
work). Leave a recorded CDR on PAUSE for a few hours - the laser runs
over the same sector OVER AND OVER AND OVER, which makes this equivalent
to playing the disc THOUSANDS of times. I've tested a disc for 4 hours,
no problemo. I'm tempted to calculate how long it would take to equal a
million plays, and test it that long, but it seems excessive.
quoted 2 lines Leave any CDR out in the sun
>Leave any CDR out in the sun
>and see what happens. It's not pretty.
I have, face up, for an afternoon. It still plays and looks just fine.
If you'll refer to the Nov.'95 issue of Mix Magazine (a pro recording
mag), you can read how Stephen St.Croix left 3 CDRs in direct Arizona
SUMMER sunlight for 12 days, and they played fine. But realistically, how
often do you plan to leave a CDR in direct sunlight? This is an extreme
condition that does not accurately reflect conditions inside a CD player,
or in a sane person's CD storage area.
quoted 5 lines You have to go for the gold ones if you
>You have to go for the gold ones if you
>want your information to last under regular use. Blue & Green (cyanoacrylate)
>CDRs are a smidgen cheaper but pretty weak in the long run. The gold lasts by
>virtue of being tremendously reflective and thus absorbing very little of the
>light spectrum.
First, the blue and green are metal-stabilized cyanine, not cyanoacrylate
(that's super-glue - do a websearch on the word and you find lots of
references to urban legends, which is how I'd classify your post, BTW).
The metal stabilization has improved quite a bit over the years, and
they'll now last almost as long. The gold type lasts because it is
phthalocyanine, which is slightly more light-stable than the latest
metal-stabilized cyanines. Phthalocyanine is almost colorless, which
means it is tremendously TRANSMISSIVE, and reflects very little light.
There are also silver phthalocyanine CDRs (Ricoh Platinum), which have a
different backing material. See
http://www.cd-info.com/CDIC/History/Commentary/Parker/stcroix.html for
some debunking of the "phthalocyanine is inherently better" myth, which
incidently got started by an article by the previously mentioned
Mr.St.Croix in the July '95 Mix.
The biggest myth about the longevity of CDs & CDRs is that the playing
side is the most important side to protect. Not true - scratches are so
far away from the pits that they are out of focus to the laser. I've seen
CDs that were used as frisbees, looking like they were buffed w/
sandpaper, that still played fine (watch out for those long circular
scratches, though). The side that's much more prone to damage is the
label side, which is protected by a thin coat of lacquer and whatever ink
is printed on (take care w/ those AB3's!), or in the case of better
quality CDRs, a coat of teflon or other protective coating. I dropped a
cheapy CDR today, 2 1/2 ft., and it took a big chunk out of the backside
of the disc - it wrecked 3 songs. Damn! From now on I'm going to put
labels on them (I only use cheapies for archival copies that I keep in the
basement, they don't play in the car very well).
I'm a firm believer in personal experience. I try stuff myself when
possible, and when I can't, I avoid quoting impressionable idiots who
repeat every old wives tale they hear. And I try to do at least some
basic fact-checking. Cyanoacrylate? Sheesh!
Che