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#1
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"Disc Rot" - USA Today Article
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#2
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David Morgan \(MAMS\) wrote:
http://www.usatoday.com/tech/news/20...tm?POE=TECISVA I'm not sure I buy this. If you look at a brand new CD right off the line, you'll see lots of little pinpricks in there, just due to defects in the sputtering process. If air gets to the disc surface, the aluminized layer should turn white, and opaque, not clear. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#3
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Air bubbles. Geez, who but someone that works with metals all the time
would have known? I mean, put copper into galvanized steel and you have corrosion. Aluminium doesn't like the iron in egg yolks, although copper is ideal for whipping eggs. Even the southwestern native Americans figured out that you need some carbon with blue corn to produce a food that has some nutritional benefits (something about the micro-composition of the starch in the blue corn not being able to become sugars because it's a molecular mirror atom). How the **** did they figure that out? Drop a blue corn tortilla into the coals and then eat it anyway? For a thousand years? But the guys that made the newest techology for storing information couldn't figure out how to put down a layer of lacquer without getting the ****ing air bubbles out of it yet. Now if they could atomically build the air bubble like a bee's octagonal hive, no problem, but I'm not going to give the idea away! g -- Roger W. Norman SirMusic Studio "David Morgan (MAMS)" wrote in message .. . http://www.usatoday.com/tech/news/20...tm?POE=TECISVA DM |
#4
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"Scott Dorsey" wrote in message
... I'm not sure I buy this. If you look at a brand new CD right off the line, you'll see lots of little pinpricks in there, just due to defects in the sputtering process. If air gets to the disc surface, the aluminized layer should turn white, and opaque, not clear. At what, 690 to 760 ns red laser light frequencies you expect to see microscopic ionization? But it would be enough to throw the reflected light of lasers off, or the optical readers are too good. Perhaps less stringent specs on the readers? Perhaps, as even fabricators have come to realize, you need to REMOVE THE AIR from the lacquer lest it affect the outcome of the product you're trying to build. Mostly I'm thinking of Polyeurathane molding, but I believe it could apply here, too because the product is cheap enough for most people to simply replace. -- Roger W. Norman SirMusic Studio |
#5
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What bothers me about the article is the implied claim that the disks wouldn't
play because they have all these pinholes. Even a CD with hundreds of pinholes should play correctly. A pinhole should never be enough to cause mistracking, and it doesn't represent enough data loss to require interpolation. I could not find an address for the author. Natch. |
#6
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William Sommerwerck wrote:
What bothers me about the article is the implied claim that the disks wouldn't play because they have all these pinholes. Even a CD with hundreds of pinholes should play correctly. A pinhole should never be enough to cause mistracking, and it doesn't represent enough data loss to require interpolation. No, but if there is a steady increase in the number of pinholes as disks age, it could get to the point where the data loss is significant after some period of time. But since most discs ship with pinholes from the factory, the existence of pinholes should not be an indication of progressive degradation. I could not find an address for the author. Natch. will be a start, I suppose. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#7
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#8
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andrewunix wrote:
Thu, 6 May 2004 10:24:27 -0700, suggested: : What bothers me about the article is the implied claim that the disks wouldn't : play because they have all these pinholes. : : Even a CD with hundreds of pinholes should play correctly. A pinhole should : never be enough to cause mistracking, and it doesn't represent enough data loss : to require interpolation. Could be an issue with DVD recordables, though. I dunno, the dye fading issues are so severe that I doubt any metallization layer problems will be even a minor issue in comparison. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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But since most discs ship with pinholes from the factory, the existence
of pinholes should not be an indication of progressive degradation. Correct. Which is another point the article didn't address. Oxidation does not produce pinholes -- it darkens the aluminum. If the coating had "really" started to deteriorate, I would expect something worse than pinholes. |
#10
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I think the writer was confused by references from years ago about video laserdiscs. "Disc
rot", aka "laser rot", was a term that described a progressive degeneration of disc reflectivity caused by impurities in the water used in the LD pressing process. Generally took a few years to show up, a caused "sparklies" in the video, eventually to the point where the disc is unwatchable. Not at all applicable scenario in CD or DVD manufacture, as far as I know. -- Stephen Sank, Owner & Ribbon Mic Restorer Talking Dog Transducer Company http://stephensank.com 5517 Carmelita Drive N.E. Albuquerque, New Mexico [87111] 505-332-0336 Auth. Nakamichi & McIntosh servicer Payments preferred through Paypal.com "Scott Dorsey" wrote in message ... andrewunix wrote: Thu, 6 May 2004 10:24:27 -0700, suggested: : What bothers me about the article is the implied claim that the disks wouldn't : play because they have all these pinholes. : : Even a CD with hundreds of pinholes should play correctly. A pinhole should : never be enough to cause mistracking, and it doesn't represent enough data loss : to require interpolation. Could be an issue with DVD recordables, though. I dunno, the dye fading issues are so severe that I doubt any metallization layer problems will be even a minor issue in comparison. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#11
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Stephen Sank wrote:
I think the writer was confused by references from years ago about video laserdiscs. "Disc rot", aka "laser rot", was a term that described a progressive degeneration of disc reflectivity caused by impurities in the water used in the LD pressing process. Generally took a few years to show up, a caused "sparklies" in the video, eventually to the point where the disc is unwatchable. Not at all applicable scenario in CD or DVD manufacture, as far as I know. MIGHT be applicable to double-sided "sandwich" DVDs, which use a similar cementing process. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#12
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"William Sommerwerck" wrote in message ...
What bothers me about the article is the implied claim that the disks wouldn't play because they have all these pinholes. Even a CD with hundreds of pinholes should play correctly. A pinhole should never be enough to cause mistracking, and it doesn't represent enough data loss to require interpolation. I could not find an address for the author. Natch. Well, the author's name is Peter Svensson and he works for Associated Press. Headquarters 50 Rockefeller Plaza New York, N.Y. 10020 Main Number +1-212-621-1500 According to this page (http://www.ap.org/pages/contact/contact.html) "Individual phone numbers and e-mail addresses are not available to the public." and "For general questions and comments;or to contact a specific employee: " According to this page (http://www.ap.org/pages/about/faq.html) 14. How do I contact a reporter or editor? Send an email to info@ ap.org and it will be forwarded to the reporter or editor. So you may not be able to get enough info to make his cell phone ring at 3 am or stake out his house but you can probably get a message through to him. |
#13
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On Thu, 06 May 2004 13:46:51 GMT, "David Morgan \(MAMS\)"
wrote: http://www.usatoday.com/tech/news/20...tm?POE=TECISVA DM This is a "Readers Digest" type publication? They usually manage to take a grain of truth and distort it in a panic-raising way :-) CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm "Possibly the world's least impressive web site": George Perfect |
#14
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David Morgan (MAMS) wrote:
http://www.usatoday.com/tech/news/20...tm?POE=TECISVA DM Pity he hadn'tchecked them all when new. My guess is they were the same. The non-playing **disc** may have been for other reason. geoff PS My old Dire Straits Communique got the fungus, but that's a different syndrome I guess. |
#15
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Scott Dorsey wrote:
William Sommerwerck wrote: What bothers me about the article is the implied claim that the disks wouldn't play because they have all these pinholes. Even a CD with hundreds of pinholes should play correctly. A pinhole should never be enough to cause mistracking, and it doesn't represent enough data loss to require interpolation. No, but if there is a steady increase in the number of pinholes as disks age, it could get to the point where the data loss is significant after some period of time. But there is nothing in the article to suggest an actual increase in 'pinholes', though that was the inference. geoff |
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