Reversal Clearing Bath Problem - Sodium Sulfite or Metabisulfite
Posted 16 January 2011 - 10:34 AM
Following Ilford's B&W Reversal Fact Sheet,
I've been experimenting with using Ilford Bromophen 1+1 (with nothing else added) as a first and second developer when processing Super 8 & 16mm Kodak Tri-X.
The Ilford fact sheet suggests using the Sulphuric Acid - Potassium Permanganate bleach bath.
Following this Ilford recommends using Potassium Metabisulphite 25g added to 1 litre water, as a clearing bath.
I've been successful with this combination.
Research told me that D-19 with Sodium Thiocyanate added (2g to 1 litre of Dev) was closer to Kodak's D-94 Reversal Process.
I've used this developer, then bleached with the Sulphuric Acid & Permanganate Bleach.
Inspection at this stage (after the recommended minimum of 2 mins in the bleach) showed a film that had the trace of an image and a slightly different coloured base than the result with Bromophen (peach colored with D-19 rather than 'creamy' with Bromophen)
The film is rewashed as usual (2 mins, running water, 20ºC)
But when I continue to the clearing bath the image dissolves leaving me with completley blank film.
I've noticed that the Kodak formula requests that you use Sodium Sulphite rather than Metabisulphite?
Re-development after re-exposure, yields nothing..
Is the clearing bath causing the problem, or is there something else going on here?
The bath looks cloudy after coming in contact with the film, something that doesn't happen as quickly with the Bromophen process.
Has anyone seen the difference between Bromophen and D-19 used to develop Super 8 & 16mm film.
Many thanks in advance.
Posted 16 January 2011 - 08:17 PM
so it seems what is happening is that the bath you have mixed for clearing is acting as a fixer - ie dissolving away the remaining silver halide. Are you sure there isn't some confusion in the chemicals and you haven't accidently mixed up fixer rather than clearing bath? I don't see how the different developer could make any difference. If you switch to using Sodium Sulphite 10g per litre as a clearing agent you shouldn't have any problems. You might also consider using the potasium dichromate bleach rather than the permangenate bleach. Its been a long time since i used permangenate bleach, but I recall a disadvantage was it needing to be mixed immediately before use.
Anyway, check that you haven't mixed hypo as your clearing bath.
Posted 17 January 2011 - 04:24 AM
Thanks for your reply!
I do believe that it might be your influence that has me experimenting in hand processing.
A student at the uni where I work was experimenting by bucket processing Super 8 and you kindly assisted.
It inspired me to try processing motion picture film (:
At the moment I'm on the other side of the world, looking to source materials in the UK
You could be right here, I"m pretty sure it's Sodium Metabisulfite, I mixed it fresh just before processing.
I guess I could test the 'clearing bath' with undeveloped film, if it's hypo I'll end up with blank film, right?
I've had issues in the past with emulsions 'lifting' from agressive developers or processing chemicals, though this tends to be with older 'alternative' still photography processes, I've heard that Permanganate bleach tends to soften the emulsion, if this was the case, would a pre-hardening bath help?
The result I got did look like the effect that hypo has on an emulsion, so that does seem like the first place to test!
I'll post my results shortly
Posted 17 January 2011 - 06:00 PM
yes, try dunking some unprocessed film in your clearing bath and see what you get - clear film would indicate it is certainly wrong and probably fixer, though you could probably tell that from the smell too. Clearing bath is cheap and not worth waisting film on.
Pre-hardener may work, but you would have to get advice from others about that. Usually when emulsion falls off in low temperature black and white processing it is because people have used rinse water that is too hot and reticulated the film.
Posted 17 January 2011 - 10:38 PM
Posted 21 January 2011 - 05:57 AM
I've tried testing the clearing bath with unexposed film, the bath did not remove the silver as hypo would.
My rinsing bath is approx 20ºC.
Perhaps a pre-hardening treatment might work.
John, what you're describing sounds exactly like my experience. I think the bath Ilford recomends might be ok for their emulsions, but damaging for Kodak's Super 8 Tri-X.
The frustrating thing is I actually got it to work at one point, and got a good result, perhaps I accidently made the clearing bath too weak?
Posted 28 January 2011 - 12:45 AM
Posted 31 December 2011 - 07:20 AM
I think we both made the bath too strong. I read the same Ilford data sheet and thought it would work out. I ended up developing the rest of my film by skipping the bath stage altogether and going for a more thorough wash. Looked good IMHO.
Hi John & Richard, an update on this process...
I figured out that the Sulphuric Acid / Permanganate Bleach as recommeded by Ilford's fact sheet was too strong for Super 8 / 16mm Stock.
By diluting the recommended 10% Sulphuric Acid 1+4 with water and doing the same to the Permanganate I ended up with a bleach that didn't damage the emulsion in the process.