PMK Pyro Film Developer

The PMK formula is designed as a universal developer for a wide variety of modern emulsions used under diverse conditions. PMK stands for Pyro- Metol- Kodalk. Kodak has changed the name Kodalk to Balanced Alkali, this is their proprietary name for sodium metaborate. The formula is constituted to achieve the best overall results in consideration of the following technical criteria: sharpness, maximum image stain, minimum general stain, edge effects, film speed, flexibility for the Zone System plus and minus development, stability, consistency, convenience of use and long shelf life.

All chemicals are dangerous and must be treated with respect. Please read the warnings listed here. Always use rubber gloves and dust mask when using chemicals.
METOL,. Some individuals become sensitized (develop allergic symptoms or rashes) while using Metol. If this should occur, discontinue use and consult a physician.
PYROGALLOL,. Pyro is quite toxic and is readily absorbed through the lungs, skin and mouth. Pyro is also a phenol and has the potential to cause skin burns. To be on the sate side please use rubber gloves and keep your work area clean with lots of soap and water. Brief contact with the skin will cause darkening which is not a chemical burn. Prolonged skin contact will cause a chemical burn which closely resembles a heat burn. Pyro is also very dusty, work in a well ventilated area. Do not inhale its dust. Keep containers tightly closed and away from light.


FIRST AID: If contact is made, flush with water. If extensive contact is made or if in eyes, consult a physician. If inhaled or swallowed, get medical attention at once.

STOCK SOLUTION A: It is advisable to use distilled water, but high, quality filtered tap water can be used. Use room temperature water. Take a small finger pinch of sodium bisulfate and add it to the water for the Solution A. Add the Metol to Solution A, and stir until it is dissolved completely. Add the remaining sodium bisulfite and stir until dissolved. Add the Pyro to the stock solution outside or under a ventilating hood. Stir until the pyro is disolved completely.

Chemical Amount Units
Distilled Water (75°F) 400 ml
Metol 5 g
Sodium Bisulfite 10 g
Pyrogallol 50 g
Water to make 500 m

STOCK SOLUTION B: Distilled water is a MUST for solution B. This solution is highly concentrated and a considerable quantity of the sodium metaborate may precipitate if the water is not pure. Dissolve the sodium metaborate at room temperature in distilled water. Any residual amount of this chemical will dissolve by itself after 24 hours. The small amount of residual left will not affect the solution activity even if used immediately.

Chemical Amount Units
Distilled Water (75°F) 400 ml
Sodium Metaborate 300 g
Water to make 1000 ml

The shelf life of the stock solution is indefinite. Partially filled and stoppered bottles will last for years. Always use glass bottles for the storage of developer solutions. Clear glass is fine for PMK, if stock Solution A is kept out of strong light. After a week or two, the color of Stock Solution A will turn a pale yellow color. This is the equilibrium point no further change will occur.

1 Part A + 2 Parts B + 100 Parts of water.
Example: 10 ml A + 20 ml B + 1000 ml of water make approximately one liter or working solution. Measure the quantity or water and add the A and B stock solutions. It does not matter witch is added first.
Note: When PMK is mixed together, the solution will immediately proceed through color changes from gray-green to pale amber. This is an important visual check of solution activity. If there is no color change, something is wrong. Recheck you stock solution.

The conventional temperature for film development is 68°F/20°C. During the summer month in many parts or the country, cold tap water is often much warmer than 70°F. To bring this temperature down with ice cubes is inconvenient, to say the least. For PMK each degree of increase of developer temperture, decrease the development time by 4%. Do not hesitate to use the higher tempertures. With appropriate reduction in development time, no loss of quality in the negative will result.

A plain water stop bath is excellent for all normal films and developers. Use a large volume or water and agitate roll and sheet film continuously. We recommend using our Photographers' Formulary TF-4 non-acidic fixer (Cat. No. 03-0141), since fixers with hardening agent will decrease the image stain, therefor, the use of non-hardening fixers is necessary. Do not use Photographers' Formulary TF-4 with an acid stop bath. Do not exceed the manufacturers recommended fixing time.

Place all negatives, direct from fixer, into the used developer for two minutes. Agitate every 30 seconds. The alkali after bath induces the formation of stain in the developed negative. An alternative alkaline after bath can be used if desired. The use of 5 grams of sodium metaborate per liter of water is the alternative.

Wash the film running water for 20-30 minutes. Wash all films for at least 20 minutes. The image stain increases during the wash cycle.

Ilford Film 70°F 80°F
FP4 EI=160 12 min. 7 min.
HP5 EI=400 13 min. 8 min.
PAN F EI=32 9 min. NR

For 35 mm, HP5 Plus, try EI=320 & 12 min. at 70°F.
For Ilford Pan-F, 35mm, normal strength PMK is fine, try 7-1/2 at 70°F.
For Ilford Pan-F, 120 roll film, reduce solution B by 25%.

Kodak Film 70°F
Tri-X EI=260 14 min.
T-Max 100 EI=100 12 min.
T-Max 400 EI=400 15 min.

Kodak T-Max 100 and T-Max 400 are extremely sensitive to development time and temperature. Carefully control the development time and use a temperature controlled water bath, if possible. Kodak T-Max 100 appears to have a large amount of anti-inhalation dye. This dye must be removed or shadow separation and image clarity will suffer. Kodak recommends that the developed and fixed negatives receive an additional bath in fresh fixer to remove any anti-halation dye. Photographers' Formulary TF-4 Fixer will remove this dye.
For T-Max P3200, try EI of 3200 and PMK for 10-12 min. at 80°F.

Agfa Films 70°F
AP-25 EI=16 11 min.
AP-100 EI=80 14 min.
AP-400 EI=200 16 min.

For Agfapan 100 roll film, try EI of 100 and 11 minutes.

Bergger 4x5 Sheet Film 70°F
BPF200 EI=100 11 min.

Forte Film 70°F
Forte200 EI=100 12 min.
Forte400 EI=200 15 min.

PMK Film Developer, Kit No. 01-5050, Photographers' Formulary (800-922-5255).
Pyro Tips, Maxim M. Muir,
Lotus View Camera, John Horowy, 815-282-9876,
Bergger and Forte Film, Freestyles Sales Co.
PMK Film Developer, The Film Developing Cookbook, Stephen G. Anchell and Bill Troop, p. 76
Gordon Hutching's PMK Formula, The Darkroom Cookbook, Second Edition, Stephen G. Anchell, p.174.

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Revised: May 19, 2002