Rehalogenating bleaches and fixers

[PVia]

Hi all...

I was wondering what I should do after using a rehalogenating bleach (ferri + pot bromide) and redeveloping in a lith developer? Do I fix again at this point?

Much thanks in advance...

 

[Ian Grant]

Yes because you won't have re-developed all the rehalogenated silver bromide.

Ian

 

[PVia]

Thanks, Ian!

 

[tim rudman]

Hi all...

I was wondering what I should do after using a rehalogenating bleach (ferri + pot bromide) and redeveloping in a lith developer? Do I fix again at this point?

Much thanks in advance...

Yes, you must if you want the print stable, as Ian said.
Be aware though that it will change in the fixer, sometimes a lot. In what way and how much will depend on the paper you are using, whether you started with B&W or Lith before bleaching, and how far you allow the second development to go before snatching.
Typically these prints will lighten significantly and this is more the earlier you stop the second development. prints will also shift colour, sometimes a lot. This can improve things or the reverse. The print will often change colour again when it dries though, so reserve judgement until then.
Because of the lightening you should usually aim to start with a darker print. If starting with B&W, 1/4 or 1/2 stop overexposure is a good starting point but this can vary a lot with your technique (how early you snatch from the lith especially) and with materials.
There are also other bleaches worth playing with for very different effects.

P.S. You might want to shift this to Fintan's new Lith sub group? i have no idea how you might do that though.

Tim

 

[Ian Grant]

Tim, one possibility to minimise the shift and colour change you describe would be to use a plain sodium thiosulphate fixer. The highlight tones and colour are the result of extremely fine grains of silver which are prone to being re-dissolved in the fast ammonium thiosulphate fixers most of us use these days. The bleaching of the highlights in a rapid fixer is very similar what happens if you fix a Kallitype in a rapid fixer.

Ian

 

[tim rudman]

Tim, one possibility to minimise the shift and colour change you describe would be to use a plain sodium thiosulphate fixer. The highlight tones and colour are the result of extremely fine grains of silver which are prone to being re-dissolved in the fast ammonium thiosulphate fixers most of us use these days. The bleaching of the highlights in a rapid fixer is very similar what happens if you fix a Kallitype in a rapid fixer.

Ian

Yes, thank you Ian, I should have mentioned that.
In practice I haven't found that it makes as much difference as I hoped it might though. I experimented with various plain and alkaline fixer formulae when I first got involved in this process (many years ago now ), along with discussions and advice from the founder of Speedibrews, who I know well and used to live close to me. It is interesting though how differently some papers behave, especially re colour loss on drying.
Tim