Variation of a pyro developer with acetone.

Mix chemicals in order.
Potassium metabisulphite3.3grams
Sodium sulphite anhydrous150grams
Water to make1liter

For tank use, mix 12.5 mililiters stock solution with 0.58 liters of water and 31 mililiters acetone. Develop for 25–35 minutes at 21°C.

For tray use, mix 20 mililiters stock solution with 0.28 liters of water and 6.2 mililiters acetone. Develop for 4–7 minutes at 18.5°C.

As a rule, contrast and density may be increased by decreasing the recommended amount of water to dilute the stock solution by 50%–66%. Softer negatives can be obtained by using 50%–100% more water than is specified for normal results.