The main culprit in color shifts is Eastmancolor and its permutations, at
least prior to the last ten years. Other color systems, principally true
Technicolor (as opposed to today's Technicolor company which use
Eastmancolor), and such non-pro formats as Kodachrome, Ektachrome et al. tend
not to fade quickly with age.
Kodak claims that Eastmancolor is fade resistant today since the introduction
of SP, LP and, finally LPP stock. Time, of course, will tell.
The reason for this is the nature of dyes used in the process e.g. animal vs.
vegetable dyes. True Technicolor in fact was more akin to lithography and the
only truly photographic image on Technicolor prints was the optical
Gene Stavis - School of Visual Arts - NYC