[alt-photo] stability of chemigram colors

[douglas collins]

Hello list,

Most of us who use color are aware of the harmful long-term effects of
ultraviolet radiation on our dyes or pigments (gum bichromates, Epson
pigment prints, etc), but few have probably thought about the stability of
chemigram colors, which use none.  We've done a little testing of the latter
over a 100 year span - a very impressionistic test - and the results are
posted on our blog at
http://nonfigurativephoto.blogspot.com/2011/08/lightfastness-of-chemigram-colors.html
.

We find that these colors also degrade or shift, even though they are free
of dyes or pigments.  Apparently the high-energy UV-B radiation is able to
cause movements among small grains within the emulsion.  Chemigramists will
find this interesting.

Regards
Douglas Collins