Intensifier for very weak negatives, free of fog or veil.

Pour 1 part Solution B into 3 parts Solution A, whilst stirring A rapidly.
Solution A
Uranium nitrate10
Water to make
Solution B
Potassium ferricyanide10grams
Water to make1liter

A few minutes before use, mix 5 parts of Solution A with 5 parts of Solution B. Shake the mixture and then add 1 part of glacial acetic acid (or 4 parts of 28% acetic acid). The negative will turn a reddish-brown color in this solution, the redder the tone the greater being the intensification.

Stop the action at the stage desired and wash until all the yellow coloration has been removed from the clear areas. Washing should not be unduly prolonged.

If the intensification has been carried too far, a few drops of ammonia or sodium carbonate may be added to the wash water.