I would try contacting Mike Ware. He is an authority on the iron based processes. If you do come across the original formula please do post it.
On 11-May-09, at 6:29 AM, Alberto Novo wrote:
I am writing a short article on VanDyke brown print for a school, and referring to the earlier Herschel's argentotype would be fine. I have not any details on this technique, only that it was a Fe am citrate coating developed in silver nitrate. I have a Namias' formula for a brown-black callitype developed in alkaline silver nitrate which might be a more refined approach, but I would prefer to find the original formulation.
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