For local bleaching of prints
Part A
| Potassium ferricyanide, 1% |
Part B
| Sodium thiosulfate (Hypo), 10% |
Note: As an alternative to B, one can use ordinary fixer at working strength
Mix 1 part of A with 1 part of B; dilute with two parts of water. The working solution is effective for approx 10 min.
Reduce proportion of A to get a less powerful bleach. Keep in mind that stronger solutions are better for increasing local contrast. Weaker solutions are better suited for reducing overall print density.