Questions regarding Mike Ware Cyanotype formula

[Jim Benson]

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I’m interested in trying the Ware recipe of ammonium iron oxalate and potassium ferricyanide, rather than the more traditional one of ferric ammonium citrate and potassium ferricyanide.

Is the Ammonium Ferric Oxalate [ formula (Nh4)3Fe(C2O4)3-3H2O] listed at Bostick and Sullivan the same chemical?

Also, while I don’t expect people to necessarily answer his question definitively, I am curious about disposal. My understanding is that there is no issue with washing an exposed print using the ferric ammonium citrate formula and having the water then go down the drain. Would this likely be the case with the ammonium iron oxalate prints as well?
When making up the ammonium iron oxalate, a byproduct of crystals is filtered out. I am given to understand that you would not want to sprinkle these crystals on your cornflakes. What is this residue, and how should it be disposed of?

Thank you for any help.

Jim Benson

 

[Gerald C Koch]

When making up the ammonium iron oxalate, a byproduct of crystals is filtered out. I am given to understand that you would not want to sprinkle these crystals on your cornflakes. What is this residue, and how should it be disposed of?

Ware's article says that the crystals are potassium ferric oxalate. The crystals and all other solutions can be disposed of down that drain if followed by a moderate quantity of water. They should not even effect septic tanks. The ammonium dichromate contains chromium (VI) and is a problem but is used in small amounts. Any chromium (VI) will be reduced to chromium (III) in waste treatment centers and septic tanks.