I attach her notes below and wish to officially proclaim it "Catherine's
Vandyke Formula."
>
> Ferric Ammonium Citrate (green scales) 90 grams
> Silver Nitrate 30 grams
> Tartaric Acid 15 grams
> Distilled water to make 1 litre
>
> To make:
> In separate containers, dissolve each of the chemicals in 300mls of
> water. When each is dissolved, first mix together the ferric ammonium
> citrate and the tartaric acid, then to that, add the silver nitrate
> slowly while stirring. [After exposure] Wash till yellow stain is gone
> (3 - 5 mins) and fix in 2 baths of solution of 1 tablespoon sodium
> thiosulphate to 1 litre of water for 5 mins (but i note some earlier
> postings re fixing times and washing of vandykes and permanency).
> Wash, hypo clear and wash.