I just had an interesting experience with ferric ammonium citrate. I don't know if anyone else has had this experience or not, and it may even be common knowledge, but I'll pass it along anyway.
I just started working with Van Dyke Brown printing again after about 20 years. We're going to be selling kits and made up solutions, so I was experimenting with various formulas.
I made a batch with my old favorite formula and got a heavy amount of yellow precipitate in the bottom of the beaker. So like a dumb dumb I filtered it off. (It's a movie called "Laurel and Hardy Do Photography") I made a print. Well I tried, and just got a faint image.
This morning I tried another formula. Again, same yellow crud in the beaker. Hmmm.... I'm not throwing it away, this time. Put it in the old trusty Waring Blender, put on a Fred Waring CD (he invented the thing, you know) and whirred away. This time the crud just mixed in and made the solution cloudy. Well on to the next kitchen appliance, the microwave oven.
Aha! No more cloudy solution, nice and clear. Well for a few minutes anyway. As it cooled down, the yellow cloudiness came back.
Something was wrong. I made a ton of Van Dykes in the early 70's, and large ones at that. I never had any problem with mixing this stuff up. I figured it was either the materials were contaminated, or on the other hand, too pure. I was hoping not the first one. I paid good money for a drum of the ferric ammmonium citrate, and it had already made some nice Ware Cyanotype solution, so maybe it was too pure. If the old stuff worked, what could it have been that was in the ferric ammonium citrate that allowed the material to dissolve. Perhaps it was free citric acid. I put a little citric acid in a sample of the cloudy solution and it cleared almost immediately. Case closed.
Moral of the story: if you are using a high quality grade of ferric ammonium citrate, add a little citric acid if the Van Dyke solution does not clear up.
Dick Sullivan
<center>Bostick & Sullivan
PO Box 16639, Santa Fe
NM 87506
505-474-0890 FAX 505-474-2857</center>
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