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Testing has shown that phthalocyanine dye and gold metal layer results in the most stable discs. The testing involved accelerated aging. That being said, I would have more confidence in media that survives this torture test as opposed to media that does not and that is about all you can say with confidence. Accelerated aging is what it is - a tool to make predictions in order to provide reasonable advice. The actual numbers are not really all that important, but comparing the numbers is much more useful in the decision making process. DVD-Rs do not use phthalocyanine dye. Some gold metal layer DVD-Rs are available. In light of the serious metal layer corrosion that I have observed in DVDs from testing, I believe that using a gold metal layer is the necessary choice when longevity is the issue. I will have to disagree with Jerry on this one. The metal layer integrity is one of the most important factors in disc longevity. Having a chemically stable metal layer eliminates a critical degradation pathway. Gold metal layered media can be recorded to low error rates. Silver metal layer discs tend to have better compatibility because of the higher reflectivity of the metal layer, although I have had few problems with gold metal layered discs. Gold metal layer, moderate writing speed, and good disc recorder compatibility will give you the best disc for longevity. The Kodak discs now being sold are rebranded MAM discs which have performed very well in accelerated aging tests compared to other media. Joe Iraci Senior Conservation Scientist Canadian Conservation Institute 1030 Innes Road Ottawa, Ontario, Canada K1A 0M5 (613) 998-3721 ext. 142 www.cci-icc.gc.ca