For bleaching of full prints.
Increases contrast and clears highlights
Prepare stock solutions as described below:
Part A
| x1 | x2 | x4 | |
| Potassium Ferricyanide | 1.2 gr | 2.5 gr | 5 gr |
| Potassium Bromide | 0.6 gr | 1.25 gr | 2.5 gr |
| Water, to make | 5 ml | 10 ml | 20 ml |
Part B
| x1 | x2 | x4 | |
| Sodium Thiosulphate (Hypo) | 30 gr | 60 gr | 120 gr |
| Water, to make | 120 ml | 240 ml | 480 ml |
Finally, prepare working solution as specified below:
Working solution
| Part A, | 5 ml |
| Part B, | 120 ml |
| Water, | to make 1000 ml |
To get a weaker and more slowly acting solution, reduce the amount of Part A. The solution is active for approx 10 min.
Immerse the wet print in a tray of working solution. Don't agitate, agitation tend to cause an uneven result with more bleach on print edges. Treat for approx 5-10 sec. Thereafter, rinse the print in running water and evaluate. Repeat if necessary. When satisfactory, fix and wash the print as normally.
A strong and rapid bleach is better for increasing (local) contrast. A weaker and more slowly working bleach is better for overall print reduction.
This recipe is from Darkroom Cookbook[1], Formula #173.
It is not clear (to me) why the KBr is needed. Most other recipes does nor contain KBr. Internet forums suggests solution A contain KBr since it can then also be used as a rehalogenating bath in a toning process?