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