Now, the good news... All other things being equal (like proper care and storage), the consumer at least has a choice in the organic dye type and reflective layer material when they buy CD-Rs (dictated by the various choices the manufacturers currently offer). >From the reading ("research") I've done, the manufacturers that are touting the very longest life of their CD-Rs typically use phthalocyanine as the dye chemistry (because it is more stable than azo, and azo is more stable than cyanine dyes), and gold (Au) for the reflective layer material due to its high marks in the 'resistance to oxidation' department. I read a Kodak study and their goal of long life for their Kodak PhotoCD Gold discs drove them to use these materials (phthalocyanine dye and gold reflective layer). If your CD burner software does not tell you the dye chemistry type/manufacturer (type 0, 1, 2, 3, 4, 5, 6, 7, 8, 9) for your disc, there are utility programs out there that should be able to help you in this regard (probably less error-prone than the "eyeballing it" method of identifying dye type). One web site I stumbled upon lists a handy chart which you can use as a "look-up table" to translate the type number to the actual dye chemistry and manufacturer: http://www.cdmediaworld.com/hardware/cdrom/cd_dye.shtml (I do not know how accurate that information is, but finding a "second source" to verify the information presented in the table would be useful.) Staying on topic of CD-R media only, from what I've read, I personally would feel a bit uneasy if I had some older discs that used cyanine dye. If the data was really important, I personally would copy the CD-R over to a CD-R that used azo or phthalocyanine dye (with my preference being phthalocyanine). But everyone has to make their own decisions in a case like this. And for very serious stuff that I did not want to waste my time periodically checking in the future, I personally would use a CD-R that is recommended by the manufacturer specifically for long-term archival purposes. The "cream of the crop" appears to be a combination of phthalocyanine as the organic dye chemistry and gold as the reflective layer material. Obviously this combination appears to be the most expensive, but it might not be as expensive as you might think (expensive is a subjective term). Again, just focusing on CD-R media (other storage media and backup strategies aside) there are choices out there for the consumer to make. If this is important to you, please do your research and make your own decisions based on what you've learned. There are a lot of white papers and scientific test results out there to wade through. There is also a lot of science and engineering behind this technology -- as always, the devil's in the details. But you have a choice as a consumer and that is a good thing! Best regards, Ken Pergola P.S. I'm definitely no expert on this subject and my experiences are anecdotal, but I think I've learned more about CD-Rs (more than I probably wanted to know) after that article came out that prompted me to start this thread. -- View this message in context: http://www.nabble.com/-OT-Is-your-oldest-CD-R-still-readable--t907869.html#a2399610 Sent from the MicroControllers - PIC forum at Nabble.com. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist