> A dichromated casein process is described in _Gum Dichromate and Other
> Direct Carbon Processes, from Artigue to Zimmerman_. There was a
> commercially available paper in Germany, ca 1905. I found the French
> patent and translated the info in the above described book, which is
> available in many libraries.
>
> Luis Nadeau
Thanks for posting this additional reference, Luis.
My previous reference to Peter Fredricks book is probably a red herring:
his alternative colloid is egg tempera, described in an article in the
British Journal of Photography for 9 April 1992. Formerly an experienced
gum printer he now prefers to use not just albumen, or the yolk, but the
whole egg! China Hamilton also mentions albumen instead of gum in an
article on his "Dichromatype" process in the Photographic Journal for
October last year (his process involves adding silver nitrate to his
dichromated colloid).
Philip Jackson
pjackson@nla.gov.au