Super-proportional reducer for very hard negatives such as over-developed and over-exposed negatives.

This reducers will attack the heavier densities (highlights) first.

IngredientQuantity
Mix chemicals in order.
Ammonium persulphate
40
mililiters
Water to make
1
liter

Note: The solution must be used immediately after it has been prepared, as it soon loses its activity.

It is not suitable for negatives which have been developed in Amidol.

To arrest the action of this reducer immerse the negative for half a minute in a 10% solution of Sodium sulphite, then wash for 15–20 minutes.