Kallitype with Fe(III) Ammonium Oxalate?
I've been doing Kallitypes for a while using the normal ferric oxalate/silver nitrate sensitizer. After reading Mike Ware's discussion of ferric oxalate -vs- ferric ammonium oxalate (and running low on the former) I tried using the ammonium as a direct replacement (20% w/v with 1% w/v oxalic acid acid + 10% w/v silver nitrate mixed 1:1).
I got pretty good results, very nice tonality but a little weak. I did this off the cuff and expect I may need more of the ammonium to get an equal amount of ferric ions in my sensitizer, but before I reinvent the wheel, has anyone done this?
My primary interest in the ammonium is that it's cheaper, easier to find, and much more soluble.