#CD-ROM media
9 messages in this thread
I've just received a Personal Scribe 500 subsystem. I have a couple of
questions.
How do I label the disks? If I use a gummed paper label (like a mailing label,
but smaller), will its weight or thickness throw the disk off balance? Will
the adhesive affect the disk (either the clear plastic or the metallized layer?
Blank Philips disks seems more available than the Kodak disks supplied with the
recorder. Since the recorder is manufactured by Philips, I think they should
be compatible (Philips Professional CD Recordable 63 min/600MB). Comments?
The Philips disks are marked with a couple of warnings.
Do not put in direct sunlight for a prolonged period. What is the
disk made of? Why would sunlight hurt it?
Write only with special marker. What special marker? Where do I
get one? (I assume a Sharpie isn't suitable.)
Thanks, Fred
Fred,
<excuse me for jumping into a different section> Paper labels are ok — we use
them all the time, and can even sell you blanks for printing in a laser printer
if you like. They are light weight enough, and the disc is spinning fast
enough, that they doesn't cause problems. The adhesive may take a year or two
off the expected 50-year life span, but nothing significant, I think. Put the
label on the top (metalized) surface, not the clear substrate, or the player
can't read the disc. Just don't try to remove a label once it's stuck. You
could damage the metalized layer, which would ruin the disc.
CD-R discs are, or should be, standard, and should work in any CD-R machines.
We've had some poor results with some brands, and perfer to use only Taiyo
Yuden/DIC Digital discs, which we do resell as well.
The reason for not leaving a CD-R in the sunlight is that the dye that composes
the data layer is photosensitive, and potentially some of the broad-band
spectrum in sunlight might damage it. CD-R discs are made of polycarbonate
(the clear plastic), the dye (an organic compound), gold, and lacquer on top of
the gold to keep it from rubbing off. Actually, the lacquer might be the most
vulnerable part of the disc — either from heat or abrasion. This is why
Philips recommends using only a felt-tip pen to mark on it — to avoid
scratching the lacquer and the metal.
Since a CD player (rom or audio) needs to reflect its reading laser off the
metal, the metal must stay shiny and uninterrupted. With mass replicated
("silver") discs, this is even more critical than with the gold CD-Rs, since
the metal is usually aluminum, which oxydizes readily if exposed to air. Gold
doesn't tarnish, but it can be scratched since it is very soft and the layer on
a CD-R is extremely thin.
I hope this answers your questions. If not, or if you have more, please let me
know.
Kathy Cochrane
[Section 6 sysop]
Just wanted to confirm what Kathy said. I think the most important reason for
keeping CD-R discs out of the sunlight is the same reason for keeping standard
CDs, LPs, Laser Discs, and tapes out of direct sunlight: They tend to warp
when they get hot in the sun.
Thanks. I didn't realize the CD-Recordable medium uses dye as the recording
material. Sunlight is certainly bad for dyes. Since it is organic, have any
tests been done on suceptability to damage by organic vapors? I'm thinking of
our off-site storage boxes that are lined with foam rubber. Will the
outgassing of the foam hurt the disks (maybe over a period of many years)?
Fred
Fred,
<here I go again, Matt. Tell me to go away if you like <g> >
The dye layer *should* be sealed away from any external influences such as the
gas from foam rubber. You only have to worry if the integrity of the disk is
interrupted (i.e., the lacquer and metal scratched, or the polycarbonate
cracked.) If the gases from surrounding materials corrode the lacquer, you
still have the gold layer, which is pretty much impervious to that sort of
thing (the noble metal — incorruptible, and all that). If it concerns you,
don't leave the discs in the same box with gaseous materials. You don't need
to protect CDs from shock the way you do hard disks, so foam lined boxes are
proably overkill, anyway.
Kathy
Heck, no. I'm glad to have you hear. Besides, I stuck my nose into your forum
first <g>.
Thanks. I just didn't want to be *too* obnoxious! You're perfectly welcome to
kibitz in our section anytime, too.
Kathy
Thanks for the information. You mentioned an estimated 50 year life. How did
you come by this? Is this a published lifetime?
Fred
Fred,
I've been told this by people who have seen test data, but I have not
personally seen such studies. Don't know if they're published or not, but I'll
find out.
Kathy