Pyrocat HD and Mod.

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Pyrocat-HD and Mod


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The original Pyrocat-HD formula by Sandy King is as follows and Sandy's favourite is shown after:

Stock A
Distilled Water 75ml
Pyrocatechin 5g
Phenidone* 0.2g
Sodium metabisulfite 1g
Potassium bromide 0.1g
Water to make 100ml

Stock Solution B
Distilled Water               70ml
Potassium Carbonate    75g
Water to make              100ml

* 0.25 grams of Metol may be substituted for the Phenidone with a slight loss in film speed but possibly better keeping qualities. Sandy King originally said 2.5g Metol could be used to replace the Phenidone but later found that 1/10th the metol gave the same developing action. Therefore adding 0.25g metol to the above formula should work in the same way. I have never used this new formula. (See Pytrocat-M below.)

For extra longevity, stock A can be made by dissolving the Pyrocatechin and Phenidone in 75ml of warmed glycol (65c - warm in water bath). Dissolve the metabisulfite and bromide in 7ml of warm water and add to the glycol mix. Top up with fresh glycol to 100ml. Will keep for years.

To make a standard working solution:

• Mix 1 part A with 100 parts water and then  add 1 part B just before development (1:1:100)
• For greater contrast, double the amount of B (1:2:100)
• Use 30 seconds initial agitation and 5 seconds each half minute thereafter
• For shorter development times use 2:2:100

Solution A keeps for 6 months in a tightly secured container (glass or PETE). Solution B keeps indefinitely.

Approximate developing times and dilutions at 20C: 

EFKE 25                  8 mins         1:1:100
FP4+                       12 mins       1:1:100 - great combo
Tri-X                        14 mins       1:1:100
Acros @ISO50       12 mins        1:1:100
TMax100                 7 mins         2:2:100
TMax400                 7 mins         2:2:100


Sandy King has stated that Pyrocat HDC is his favourite Pyrocat Brew.

It's made with propylene glycol and uses Ascorbic acid instead of metabisulphite and bromide.

Pyrocat-HDC formula by Sandy King (Solution A mixed in glycol).

Part A (to make 100ml)

  • Propylene Glycol 50C 75 ml
  • Pyrocatechin 5 g
  • Phenidone 0.25g
  • Ascorbic Acid 0.4g
  • Propylene Glycol to 100ml

Sandy says, "Pyrocat-HDC gives almost identical results as Pyrocat-HD with most films and development methods."

Minimal agitation by Sandy follows:

"I use a variation of semi-stand development that I call minimal agitation.

The working solution is:
1.5 A + 1 B + 150 water.

I pre-soak for five minutes, then drain and pour in solution A. My initial agitation is vigorous for 60-90 seconds, then I agitate again for 15 seconds at the 1/4, 1/2 and 3/4 points of development.

With this dilution and agitation routine the contrast will increase steadily for up to 1.5-2 hours. With Delta 100 a total development time of 45 minutes should be a good starting point.