Antwort: Re: [altphotolist] Persistent cyanotype spots


Correction: Third (last) Link (4% Gelatin) should be

Udo schrieb: -----
Von: "BJ68,"
Gesendet von:
Datum: 18.02.2021 09:04
Betreff: Antwort: Re: [altphotolist] Persistent cyanotype spots

a) Ammonium nitrate is a restricted substance at least in the EU see Annex I in;from=EN and even if you are a professional user (in German "Gewerblich") it can be difficulty to obtain a small amount.

b) Other suggestions:

1. Adding gelatin and glutaraldehyde to your cyanotype chemistry see (in English) 6% are to much (emulsion is to viscous) so I cut it to 4% see (in German only). Mixtures are stable for more than 1.5 years @ RT (room temperature) see
Modification would be to take only the gelatin and reduce the amount to 1 to 2% @ the potassium ferricyanide solution. Should gave you a additional layer with will stain your spots.....

2. Not tested: To replace the gelatin from recipe above with polyvinyl alcohol or polyvinyl acetate, which will make the same...adding a layer where the formed pigment will be withhold, covering the areas of the spots after development.


Join to automatically receive all group messages.