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Formulas & Procedures

In response to requests to put in one place the formulas we use in the darkroom, we are posting them here. Fuller information on their use can be found in the various articles.

Formulas from Michael A. Smith and Paula Chamlee

 ABC Pyro
 Solution A
 Water  900 cc
 Sodium Bisulfite  10 g.
 Potassium Bromide (10% Solution)  11 cc
 Pyro  60 g.
 Water to make  1,000 cc (One liter)
 Mix at 100 degrees
 Solution B
 Water  900 cc
 Sodium Sulfite  105 g
 Water to make  1,000 cc (One liter)
 Mix at room temperature. Solution B keeps less well than solution
 A or C. You might want to mix it shortly before use to insure
 consistent results.
 Solution C
 Water  900 cc
 Sodium Carbonate  80 g
 Water to make  1,000 cc (One liter)
 Mix at 100 degrees

For use: 1-1-1-7 (the 7 parts is water)
For subjects with extreme contrast use: 2-1-1-15

We develop by inspection and generally start looking at 8 minutes. All films will vary in this regard.

 To mix a 10 % solution of Potassium Bromide (KBr)
 Water  400 cc
 KBr  50 g
 Water to make  500 cc

Stop Bath

28% Acetic Acid 100 cc per each 1/2 gallon of water Use for about 30 seconds

 To make close to one gallon of 28% Acetic Acid from 99.5% Glacial Acetic Acid
 Water  64 ounces
 Glacial Acetic Acid  33 ounces
 Water  24 ounces
Mix this outside. DO NOT breathe fumes from Glacial Acetic Acid.


Rapid Fix without hardener for 4 minutes

We then use Perma Wash for 5 minutes and follow with a 30-minute wash


Developer: Amidol for use with Azo. Mix at room temperature just before use.

   One liter  1.5 liters  3 liters  4 liters
 Water  900 cc  1,300 cc  2,500 cc  3,000 cc
 Sodium Sulfite  30 g  45 g  90 g  120 g
 Citric Acid  3 g  4.5 g  9 g  12 g
 KBr (10% solution)  2 cc  3.65 cc  8 cc  11 cc
 Amidol  8 g  11 g  20 g  24 g
 Water to make final amount. Develop for no more than one minute.

Developer: Amidol for use with Enlarging Paper. Mix at room temperature just before use.

   One liter
 Water  900 cc
 Sodium Sulfite  30 g
 Citric Acid  3 g
 KBr (10% solution)  6 cc
 BB Compond 1% solution (or Benzotriazole 1% solution)  60 cc
 Amidol  8 g
 Water to make  1000 cc
 Develop as long as needed (generally 2-3 minutes)

Stop Bath

Acetic Acid 28% 100 cc per each 1/2 gallon of water Use stop bath for 10 -15 seconds.


32 ounces dry measure Sodium Thiosulfate Prismatic Rice Crystals per each gallon of water. Mix at around 90 degrees. We mix 10 gallons at a time as a stock solution.

For use: To each 1/2 gallon of fixer Add 25 g of Sodium Bisulfite.
Fix for 30 seconds. Turn on the light. Inspect print. Fix additional 3,5 minutes (4 minutes total).

Second Fixer

Sodium Thiosulfate without bisulfite Use for 4 minutes.


 Water  128 ounces
 Perma Wash  3 ounces
 Rapid Selenium Toner  1 ounce
 Use for 3 minutes.

First Wash: 1/2 hour

Perma Wash

3 ounces Perma Wash to 1 gallon water.

Use 5 minutes.

Final Wash: One hour

Dry Prints face down on nylon drying screens.

Flatten Prints in dry mount press for 15 seconds.

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