Re: Antwort: Re: [altphotolist] Persistent cyanotype spots

Chris Seiberling,

Thanks, Udo. I’m still trying to secure some ammonium nitrate— the hurdles in the US appear to be not quite as high— but am taking note of your solution.
Chris Seiberling

On Feb 18, 2021, at 3:17 AM, BJ68, <> wrote:

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.


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