Re: ferric ammonium citrate
S_IZZO@guvax.acc.georgetown.edu
Fri, 06 Dec 1996 15:33:20 -0500 (EST)
Tom Ferguson suggests that Judy's problem with the ferric ammonium
citrate may be the age of the chemical which may go bad even in the
dry state. My experience suggests that this is unlikely to be the case.
For the first cyanotypes I made, I used chemicals that had been in
my father's darkroom for at least 30 years (probably closer to 50 years).
The ferric ammonium citrate was a rock hard mass in the bottom of a
Mallinckrodt jar labeled "quarter pound, Iron & Ammonium Citrate,
U.S.P. XI Green Pearls, (Soluble Ferric Citrate)". At the bottom, the
label has this: "CAUTION: To be used only by or on the prescription of a
physician, dentist or veterinarian, if used medicinally." (What was it
used for?) Anyway, I had to chisel out chunks with a hammer and old
screwdriver. In spite of its age and condition, it mixed up the light
yellow-green color that it was supposed to and the prints were fine.
I have had cyanotype solution turn dark blue (sometimes it prints
up fine and other times the highlights are light blue), but I've never
seen it turn brownish. Good luck in tracking down the problem.
Suzanne Izzo