Originally Posted by Joe VanCleave
I don't take it as argumentative.
My statement about the life of a color photographic material is based on several things. First, there is a statement on Kodak's web site regarding the longevity of Kodak Endura paper. Second, Fuji has made a similar statement to the photo industry. Third, Henry Wilhelm discussed this with me personally and his institute has published data on longevity. Fourth, the Image Stability lab at RIT is in general agreement with this data. Fifth, I took the ICIS course on image stability in May. And, last but not least is my more than 30 years experience as an engineer at Kodak, with about 1/2 of that time being involved in some way with image stability.
Now, the disagreement in value centers around the testing method. You get different results with each paper depending on how you test it. And, the ANSI committee on image permanence has yet to make a definitive statement on this subject with definitive standards, so each lab makes its own standard.
Nowhere in this thread was handcoating discussed that I know of. This was solely a discussion about manufacturing color products. They cannot be easily hand coated, although I have done it. It is truly a pain, and very expensive due to the chemistry and equipment needed.
I do not wish to have an argument with Ryuji. I merely state facts from my actual hands-on experience along side his observations from the literature. Sometimes they agree and sometimes they don't agree. This is often the nature of printed material vs hands-on in engineering and should not reflect badly in any way on either of us.