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The Pyrocat Developers

Sandy King developed Pyrocat HD – a semi-compensating staining film developer with high accutance. He then developed other fomulas (the glycol ones with the help of Pat Gainer) that work with subtle differences.  These developers seem popular with shooters of all formats. Some photographers think the tanning action of the Pyrocatechin helps reduce scrathes in soft X-Ray film.

Pyrocat HD – Part A

Distilled Water (50 C) 750 ml
Sodium Metabisulfite 10 g
Pyrocatechin 50 g
Phenidone 2 g
Potassium Bromide 1 g
Distilled water to make 1 L

 

Pyrocat HD – Part B

Distilled water 750 ml
Potassium Carbonate 750 g
Distilled water to make 1 L

 

You can use Sodium Carbonate instead of Potassium. Use 75% of the amount recommended. Most folks say Part A lasts about a year in a glass bottle, and that Part B lasts indefinitely. I have seen Part B go bad. As a result, I computed the actual amount of carbonate in the mixed developer for each of my tank sizes, then mix the developer by starting off with Part A, adding the correct amount of water, then stirring in the correct amount of dry carbonate. That’s one less solution to mix and is simpler in my mind.

The following formulas are for Part A and use the same Part B as above.

Pyrocat-P

Distilled water at 120F 750 ml
Sodium Metabisulfite 10 g
P-Aminophenol 5 g
Pyrocatechin 50 g
Water to make 1 L

 

Pyrocat-M

Distilled Water at 120F 750 ml
Metol 2.5 g
Sodium Metabisulfite 10 g
Pyrocatechin 50 g
Water to make 1 L

 

Pyrocat-PC

Propelyne Glycol at 150F 750 ml
Pyrocatechin 50 g
P-Aminophenol 5 g
Ascorbic Acid 4 g
Glycol to make L L

 

Pyrocat-MC

Propelyne Glycol at 150F 750 ml
Pyrocatechin 50 g
Metol 2.5 g
Ascorbic Acid 4 g
Glycol to make 1 L

 

Mixing directions for MC – Start with about 8 ml TEA (triethanolomine) at room temperature and a spoonful of water. Add the metol and stir to make a slurry. After the slurry gets more fluid, add 15-20 ml warm glycol. Transfer the slurry to the 750 ml warm glycol and stir until dissolved. Then add the Pyrocatechin and stir until dissolved. Then the Ascorbic Acid.

These developers can be used at various strengths – probably most common are 1:1:100 for printing on regular silver gelatin paper or 2:2:100 for printing on chloride papers or alternative processes.  I happen to like 1.5:1:100 for scanning.

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