Printing out paper with silver oxalate

a very ineresting formula from the old Soviet source.

Printing out paper emulsion [1]

This emulsion contains a free silver nitrate, which can interact with the paper base. Cotton paper is required. The emulsion is low light sensitive and can be processed in diffused daylight.

Three solutions are prepared.
1. Silver nitrate 24g
Water 160ml

2. Sodium chloride 2.1g
Water 700ml
Gelatin 70g

3. Oxalic acid 5.4g
Ammonium chloride 2.1g
Tartaric acid 9.6g
Sodium bicarbonate 1.05g
Water 140ml

The temperature of all solutions is brought to 55°C. The 1st solution is poured into the 2nd, then the 3rd solution is poured into the mixture (1+2). Ripening - 30 min. Add 40ml alum solution (probably 10% potassium alum) and 20ml ethanol before coating.

[1] Mikhailov - The Technical Minimum for the emulsioners (1935), in Russian
https://archive.org/details/mikhailov1935

I recalculate this formula for 40g/L AgNO3 and gelatin-to-silver ratio 2.0. My emulsion contains 50% AgCl and 50% silver oxalate.

My POP emulsion N-200419 and technique

For 100 ml emulsion two solutions are prepared.

1. Silver nitrate 4.0 g
Water to make 30 ml

2. Potassium chloride 0.88 g
Potassium oxalate *1H2O 1.2 g
Tartaric acid 0.5 g (**)
Disodium edta 0.2 g
Gelatin 5.1 g
Water to make 70 ml
Alcohol 0.5 ml

The temperature of 2nd solution is brought to 55°C and alcohol (antifoaming agent) must be added just before the precipitation. The 1st solution (20°C) is poured into the 2nd with stirring. Ripen 30 min at 60°C in the waterbath, stir every 5 min. Cool down to 40°C and add finals:

glycerol 50% 0.2 ml
thymol 10% in isopropanol 0.2 ml
wetting agent 1 drop
ethanol 2 ml

For coating take 63 ml emulsion per 1 m2 paper (loading 2.5 g AgNO3 per 1 m2). I prefer to coat the wet paper with silicon brush smoothing.
The emulsion can be stored in refrigerator up to several years. The coated paper can be stored for no more than several mounths.

Processing POP after exporure:
1. prehardening bath (2-3 min)
2. rinsing (1 min)
3. fixing (alkaline fixer, 1-2 min)
4. toning and washing (it is the better to tone a driyed and prewetted print)

Prehardener:
Formalin 40% 10 ml
Sodium hydrogen carbonate 20 g
Sodium chloride 20 g
Water to make 1 L

(**) For doubtful paper substrate the tartaric acid quantity can be increased.

in attach - the print on this paper, loading 1.5ml per 13*18cm paper area. Toned 30-40s by polytoner (polysulfide+selenium), stoped by sulfite bath.
Print was made by contact from contrasty pyro-negative (pyrocat).