why does nobody use the second cyanotype process, the one hershel used?

Solution A: 400g ferric ammonium citrate green in 1l of destilled water (store in dark bottle)
Solution B: 10g potassium ferricyanide in 1l of destilled water

  • Float paper in solution A (or use a brush)
  • dry (dimmed light!)
  • expose about 10 times less than with the original cyanotype formula. You will see a faintly printed image on your paper. The darkest shadows should have the colour of the not-exposed paper.
  • float the paper in solution b (a brush can reduce the resolution of the print)
  • wash until all the yellow is gone.
  • dry (and wait 1h for the full contast.)

Advantages: it gives me sharper prints 10 times faster
Disadvatages: you need a lot more chemicals

try it!

p.s. this is where i found it: (in german)