When I first statrted making kallitypes and cyanotypes there was a from of
Ferric Ammonium Citrate available that had been prepared for a food
manufacturer. It came as a fine green powder. It worked well and consisitently
as long as one remembered to keep it dry. Then the food manufacturer found a new
way of adding iron to the food and this useful form of FAC went off the market.
For a time there was no practical alternative. Chemical suppliers sold a brown
version which appeared to have too much 'ferrous' in it making it unsuitable for
our purpose as it is the effect of light changing the ferric to ferrous that
gives us the photographic result we are looking for. Has anyone tried to make
prints using brown FAC ?
Now Silverprint and Process Supplies both sell a green powder with bigger
crystals in it that works.
There was, however, a period when those who did not have stocks were stymied.
Just in case this happens again, is there anyone who knows a simple way of
making the stuff on a small batch basis. I have been using home made ferric
oxalate for two years now. How can we make ferric ammonium citrate ?
Terry King