Re: Ferric ammonium Citrate SOLID?
Jacek-- I see Christina answered your question suggesting adding water (into the bottle, I assume). However, unless you know the weight of the bottle (without contents), I'm not sure how you can get the weight of the ferric ammonium citrate. Of course if you are using this for cyanotype, the exact amounts are not that critical. The first ferric ammonium citrate that I used was, like yours, a solid mass in the bottom of the bottle. I chipped it out with a hammer and chisel. Then you can weigh and mix as usual. Certainly, you should not throw it out. Suzanne Izzo