CompuServe Thread

#CD-ROM media

9 messages in this thread
#813From: Fred KnoxJul 6, 1993 6:04 PM
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
#825From: The One-Off CD ShopsJul 7, 1993 9:51 AM
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]
#827From: Matt Seitz (Meridian DatJul 7, 1993 2:52 PM
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.
#829From: Fred KnoxJul 7, 1993 4:13 PM
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
#834From: The One-Off CD ShopsJul 7, 1993 7:12 PM
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
#856From: Matt Seitz (Meridian DatJul 8, 1993 6:38 PM
Heck, no. I'm glad to have you hear. Besides, I stuck my nose into your forum first <g>.
#860From: The One-Off CD ShopsJul 9, 1993 12:21 AM
Thanks. I just didn't want to be *too* obnoxious! You're perfectly welcome to kibitz in our section anytime, too. Kathy
#828From: Fred KnoxJul 7, 1993 4:08 PM
Thanks for the information. You mentioned an estimated 50 year life. How did you come by this? Is this a published lifetime? Fred
#835From: The One-Off CD ShopsJul 7, 1993 7:14 PM
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