...
Not that I want to rain on anyone's parade, but I recently managed to see
an early manual, ca. 1890 of reproduction processes for maps, plans, etc.
and there were several specimens of processes tipped in that were very
interesting to examine.
The blueprints were in pristine shape as with the carbon and ink pictures.
Print # 9, identified as "Uranium Print, developed with Nitrate of Silver"
was badly faded, like a pale albumen print. Print #10, "Uranium Print,
Developed with Red Prussiate of Potash." was in a somewhat better shape.
Luis Nadeau
NADEAUL@NBNET.NB.CA
Fredericton, New Brunswick, Canada
http://www3.nbnet.nb.ca/nadeaul/