Mac,
I was directed to this recipe or one close to it from info published on
this net. It was referred to as "the inverse (Pellet) process". I was
interested in it because it was supposed to give a positive image using a
positive transparency. This suited my needs as I sometimes work under
pretty primitive conditions. While at the library I found a this more
descriptive formula.
Solution A: 20 parts gum arabic:100 parts distilled water
Solution B: 50 parts ferric ammonium citrate:100 parts water
Solution C: 50 parts ferric chloride:100 parts water
When combined, the colour and consistency should change as each solution is
added and the final solution should be translucent. Brush on paper as
usual, dry then print. Rinse in running water,then immerse in a solution
of 20 parts potassium ferricyanide:100 parts water. The final step
"should" give the characteristic blue of a cyanotype.
Use a fume hood or proper ventillation when combining the ferric chloride
with water, the process is exothermic at this [ ] so gives off gaseous
hydrochloric acid. (Burns your nose hairs off!)
After weeks of trial and error and wasted paper, I came across an article
in an old photo process book that says that "Pellet" invented and used the
process for blueprints so that he could get blue lines on white paper
instead of the other way round. In a nut shell, the process works best
where lines and outlines of images are used. I'm still determined to adapt
it to my needs but I haven't gotten anything spectacular out of it yet. If
you are interested in the gory details contact me at the address below.
Diane
K. Diane Eaton
Brock University
St.Catharines, On. L2S 3A1
deaton@spartan.ac.brocku.ca