Reducer formula suitable for over-exposed and/or over-developed negatives that are fogged or too dense.

Mix chemicals in order.
Solution A
Sodium thiosulphate100
Water to make
Solution B
Potassium ferricyanide100grams
Water to make1liter

For use take 100 mililiters of Solution A and add 5 mililiters of Solution B. If the contrast needs to be increased the increase the proportion of Solution B. Use pure Sodium thiosulphate in Solution A — do not use an acid fixing bath. Stop the action slightly before it appears that the desired degree of reduction has been produced as the reducing action continues for a short while during subsequent washing. Rinse vigorously and then wash thoroughly for at least half an hour.

Solution A keeps well, Solution B must be stored in a brown bottle, or out of the light. Mixed reducer solution only keeps for about an hour.