for the bleaching I do, I learned it from Bruce Barnbaum. The Potassium Ferricynide should be mixed with water to the color of a nice yellow not a strong yellow but a medium one. I do not measure. Get your print wet first then work in good light. Bruce has some nice surgical hosing set up so that he can use a stream of water as he works. I use Japanese calligraphy brushes to apply the bleach. when it is nearing the bleaching in the particular spot that I want, i hurry and put it in a tray of fixer which stops it complete from bleaching further. Use the water stream to keep the bleach solution from flowing into portions of the print you won't want it to go. Slow is good. If you try to bleach too quickly or too much at once you will have a mess. Do little spots at a time and for a little time. Once it has been in the fix, you can rinse it well and rebleach. Oh and Bruce has a nice opaque plexiglass sheet he has at an angle in his developing sink so that when the print is wet he can adhere it to it. It keeps the print at about eye level so that you can get closer to watch the bleaching action. The bigger the brush the bigger the area you can work with.
If blonde speak needs translation ask what I messed up explaining.