film bleach and redevelop

I had to try this. I initially used some throwaway negs. To obtain repeatable densities does one keep a chart with redevelopment time? I initially used pyrocat 2-2-100 and will probably use it more dilute next time. I'd like to increase density for negatives that will not print on AZO grade 2 and would need grade 3.

Also I have a few negs that are uneven in development and wonder if redevelop will help? Thanks

Bleaching a stained negative with a solution such as is used in making sepia toned prints will change the silver part of the image to the bromide without noticeably affecting the stain image. Redeveloping in a staining developer then restores the silver image and adds to it more stain. The redeveloping is usually done to completion, so the strength of the redeveloper is not of much concern. You probably want the same color of stain, so use the same developing agents. You won't build up the silver image nor will you affect the grain unless you use a solvent developer.

You can do this process more than once, but there is a limit due to tanning of the emulsion which puts strains on it that may eventually cause cracking. Even before noticeable cracking, the tanning-induced edge effects may become objectionable. Needless to say, experimenting on expendable negatives is required.

You might try bleaching and reveloping in the old Ilford IT-8 formula.

This uses a Dichromate bleach, this itself is similar to to an intensifier, and then the image is redeveloped in a Pyrocatechin developer.

Effectively this Toner stains the image twice, once with the bleach and then with the developer. While designed for prints it works as an excellent staining intensifier for negatives.

The toner was listed in the Formulae (Recipe) section of this site and is awaiting restoration to the new articles section meanwhile:

IT-8 Ilford Pyrocatechin Toner
For Olive Black tomes.

Stock A
Potassium Bichromate 50 gm
Water to 1 litre


Stock B
Hydrochloric Acid (conc) 100 ml
Water to 1 litre

Expose and process your print as normal and wash well.

Make up bleach from: 2 parts A and 10 parts B with 40 parts water, bleach the print then wash until all the yellow from the bichromate has been removed from the highlights then redevelop in the following Developer.

Developer

Pyrocatechin 1.75gms
Sodium Carbonate (anhyd) 5gms
Water to 1 litre

Develop to completion. Note the developer should be fresh, and discarded once it turns green.

Ian

I used potassium fericyanide and potasium bromide to bleach the negative.