Argyrotype puzzler

OK, I'm stumped.

While teaching the usual alt-photo class this summer a few students
began to experience odd color results with Argyrotypes. Instead of the
expected chocolate to mauvish brown tones, the prints were completely
nuetral gray (and quite lovely too, with a tinge of brown at the brush
stroke edges). The students reported the prints looked gray as they
came out of the UV box. here's a sample:
http://www.darrylbaird.com/ALT/Argyro_gray.jpg

After interrogating the culprits I thought that perhaps the
explaination was a hypo-CLEARING bath following the initial water
rinse. (Students are so inventive..if they hear - nobody reads
anymore-a word like hypo, then any word that looks like or sounds like
hypo MUST BE HYPO.. right???)

anyway, I tested this and just got a dull print

my current theory is one of a mild contamination, either from classic
cyanotype or potassium dichromate from gum printing, probably from
reusing a foam brush and pouring argyro solution back into the group
bottle -- a first class NO-NO, but still likely under the
circumstances (final projects are due in a week)

any thoughts about this? I'd like to explore this and see if it could
be controlled. I think I'd have to name the process snafu-otype.

thanks

Darryl Baird
Received on Thu Aug 11 15:36:04 2005