Bleaching Negatives: How to?

[gbenaim]

Hi,

I want to try to bleach some overexposed negatives to get them printable, wanted to ask a few questions. Do I need to put KBr in the ferricianide dilution as I do w prints to avoid fogging? How often do I need to refix as the negative is bleaching? When would you use a bleach and redevelop procedure, only when overexposed and underdeveloped? These are negs developed in Rodinal and pyrocat-hd. Thanks for your help.

GB

 

[gbenaim]

Just tried it w 2 negs, the rodinal neg came out fine, the pyrocat seems to have fogged. Any idea why this would happen?

 

[photomc]

Don't have an answer for you gb, but also have a pyrocat neg that I am thinking about bleaching - dumb mistake, forgot to stop down the lens so it is way overexposed - BUT, there is lots of detail in the negative so I thought about bleaching it just to see what happened. Any tips you care to pass on with your recent attempts?

 

[Ian Grant]

That fog is the staining from the Pyrocatechin. As the staining is in proportion to the density of silver an over-exposed negative will be dense and so the base level of staining very significantly higher.

Ian

 

[Doremus Scudder]

Getting rid of the pyro stain?

If the fog on your negative is indeed a the pyro stain, you may be able to get rid of it. I know that pyrogallol stained negs (PMK, ABC-pyro etc.) lose their stain in solutions of sodium sulfite (that's why hypo-clear isn't recommended for pyro negs). If the same applies to pyrocat stain, then you are in business; plus, you will get rid of some of the negative density with the stain. Give it a try, it can't hurt (after all, it's just a wash-aid).

I'm sure others with more pyrocat experience will chime in soon.

Do report back and let us know the results, though; I'm curious.

Oh! one more thought... If the neg is "really" dense, you could do a bleach-redevelop, and only partially redevelop the neg. You would have to bleach with a rehalogenating bleach (ferricyanide with KBr) to completion, and then redevelop in a dilute (non-staining) developer to the density you want. Tricky, but doable, and, you can repeat if you need to.

Good luck.

Best,

Doremus Scudder

 

[JBrunner]

That fog is the staining from the Pyrocatechin. As the staining is in proportion to the density of silver an over-exposed negative will be dense and so the base level of staining very significantly higher.

Ian

If the "fog" is just stain that didn't bleach, the neg will print much easier than it looks. You might not need to do anything further.