Several books suggest that cyanotypes are not very permanent i.e.
fade in strong light. Also, when first introduced, it was mostly
used for proofing. All of this would seem to suggest that it is
sort of a "second class" process. However, I, and some other list
members own some "antique" cyanotypes that are in very good condition.
For example, I have two that are dated "1900" and "1901."
To quote James M. Reilly "Care and Identification of 19th Century
Photographic Prints"
"In general, cyanotypes have deteriorated much less
than the various silver print materials used during the
19th century...........because the image will fade under
alkaline conditions, alkaline-buffered enclosures should
not be used with cyanotypes."
I attended a workshop by Mr. Reilly in Pittsburgh, PA a few years
back and asked him specifically about cyanotypes. He made one
interesting statement to the effect that because of the catalytic
activity of the platinum image and the acid rinse during processing
of platinotypes, there may be more stability problems as far as
the paper support goes, with platinum prints than with cyanotypes.
How about that.
Bob Schramm