Bleach bath action

[SalveSlog]

I reversal process (120 film) using the Ilford recipe for the bleach:

Solution A: 2g potassium permanganate in 500ml water.
Solution B: 2% sulphuric acid.

Mixing 250ml A with 250 ml B just before processing works as predicted by Ilford for FP4+ and Delta 100.

That bleach also works fine for Fomapan 100 Classic if I mix it less strong. Like:
150ml A + 150ml B + 200ml water.

Same for Rollei Retro 80S, but even milder seems to be required:
100ml A + 100ml B + 300ml water.

I get clear highlights with Fomapan and Rollei without using any hypo (sodium thiosulphate).

So.. I tried HP5+ using same bleach as for Fomapan:
150ml A + 150ml B + 200ml water.

This worked rather fine, but the highlights did not come out clear. I know I may have to use hypo.
But first I want to ask a question:

Can bleach only partially dissolve the silver, so as to leave some silver from the first development. Or is the action of the bleach "all or nothing"?

 

[Rudeofus]

Is there a chance that HP5+ is coated on a somewhat dense base? What happens if you throw a small fresh test clip of HP5+ directly into fixer? Does it come out completely transparent?

Are your HP5+ slides visibly denser in the highlights than what you get with that test clip?

 

[SalveSlog]

I haven't done that test but Ilfords fact sheet states that the base for 120 film is clear. Also, I can see the grain.

 

[davedm]

Can bleach only partially dissolve the silver, so as to leave some silver from the first development. Or is the action of the bleach "all or nothing"?

Bleach action depends on amount of permanganate , bleach time and agitation. In any event, you will need to add hypo/ thiocyanate to first developer to get film to get quite clear.

However, you can do this test to check bleach strength. Expose about 10 frame length of film to room light and develop it. After developing, cut it in 1-2 frame lengths and bleach it various bleach concentrations and then fix them. See which concentration gives you as clear image as if the film was directly fixed as Rudeofus recommended. This is your bleach concentration. Keep in mind that bleach time should be 3.5 - 5 min max otherwise chances of emulsion damage are quite high.

Also, it is recommended to vary only Solution A concentration and not Solution B concentration. Acidity of solution must remain at that level for permanganate to act. Also Use as vigorous agitation as possible.

Lastly, in addition to Ilford pdf, you should go through Dead Link Removed.

 

[SalveSlog]

I reversal process (120 film) using the Ilford recipe for the bleach:
...
I get clear highlights with Fomapan and Rollei without using any hypo (sodium thiosulphate).
...

Sorry! I should have written "quite clear".
There is still some silver in the highlights. Maybe that's better than risk clipping them?

 

[Gerald C Koch]

I reversal process (120 film) using the Ilford recipe for the
Can bleach only partially dissolve the silver, so as to leave some silver from the first development. Or is the action of the bleach "all or nothing"?

No the bleach if fresh and correctly made works to completion.

Your question sounds like a problem with the first developer. Thiosulfate will clear the highlights. You need to experiment to find the correct amount. Reversal processing is a bit harder than conventional film processing.

 

[SalveSlog]

Thank you. I'm still a beginner at this and wanted to use only films that would be fine without hypo.
But on my first HP5+ film mentioned above I overexposed one frame 4 and a half stop against the sky. I can still distinguish a faint cloud from the blue sky. That's motivation to experiment with some hypo!

 

[Gerald C Koch]

Quoting from the Ilford article on reversal processing "We do not recommend reversal processing HP5 Plus or DELTA 400 PROFESSIONAL film stock. Results are likely to exhibit unacceptably low contrast." Until you become more familiar with the process I would suggest that you follow Ilford's instructions to the letter. Establishing the amount of hypo added to the first developer would probably be the last adjustment made.

 

[SalveSlog]

I exposed somewhat contrasty scenes on a roll of HP5+, 120 at 800 asa.
First developer Ilford PQ Universal in the dilution given in Ilfords paper. No hypo.
Gentle but constant turning the tank for 15 minutes.
Bleach as described in the first post.

If there is any silver left in a overexposed frame (1 second against open sky with f:4,5), I'd say it's negligible. And contrast is good as far as I'm concerned. (Beware: I've never seen professionally processed b&w slides other than on a computer screen!)
What I suspect suffer, though, is grain. It's visible with a 3x loupe on the lighttable.

 

[Rudeofus]

First developer Ilford PQ Universal in the dilution given in Ilfords paper. No hypo.
Gentle but constant turning the tank for 15 minutes.

Well, you did a number of things here:

1. you intentionally underexposed your images
2. you left out the hypo
3. you slightly extended FD time from 12-15 minutes

What is this going to do after FD step? The last item is going to give you slightly more silver in highlights, but the first two items will work in the opposite direction: Thiosulfate would have given you higher developer activity plus higher fog. Underexposure also creates less silver in highlight regions. Overall you likely end up with less silver, which also translates to dim highlights in reversal process.

PS: you develop HP5+, one of the grainiest films out there, with Ilford PQ, which is also not exactly a fine grain developer, and push process: what did you expect except massive grain?

 

[Gerald C Koch]

Well, you did a number of things here:

1. you intentionally underexposed your images
2. you left out the hypo
3. you slightly extended FD time from 12-15 minutes

What is this going to do after FD step? The last item is going to give you slightly more silver in highlights, but the first two items will work in the opposite direction: Thiosulfate would have given you higher developer activity plus higher fog. Underexposure also creates less silver in highlight regions. Overall you likely end up with less silver, which also translates to dim highlights in reversal process.

PS: you develop HP5+, one of the grainiest films out there, with Ilford PQ, which is also not exactly a fine grain developer, and push process: what did you expect except massive grain?

May I also add

4. you used a film which Ilford specifically mentions not using for reversal processing!

 

[SalveSlog]

Hi Rudeofus and Gerald

Thank you for your answers, but I hope you understand that I did not expect good results. I intentionally tried it to see what would happen and to learn about reversal processing by doing it with different films. And by failing. I learn a lot that way.
I intentionally underexposed and overdeveloped to see if that would clear the highligts without hypo. My results with HP5+ was in fact better than I expected, and my plan (kind of) worked. In fact so well that I've loaded a new HP5+ roll.

 

[Rudeofus]

Any particular reason why you left out the hypo?

 

[Truzi]

Hi Rudeofus and Gerald

Thank you for your answers, but I hope you understand that I did not expect good results. I intentionally tried it to see what would happen and to learn about reversal processing by doing it with different films. And by failing. I learn a lot that way.

I learn the same way. As a matter of fact, it is nice, but annoying, for me to get good results the first time, because that means I simply followed directions and did not actually "learn" anything about the process itself. In those cases, I typically change things the next time around just to see how they affect the result. I want "usable" results the first time, but with enough "obvious" problems that I am forced to learn something.

I'm following this thread for general information; I'll be trying B&W reversal soon, though with a different film. It's already exposed, I just need to find the time to develop it.

 

[Gerald C Koch]

Reversal processing is very different from ordinary film development. Different films respond differently to reversal. This includes following the film manufacturer's (in this case Ilford) recommendations. That is why it is important to first follow the reversal process exactly. This gives you a base line for such things as determining the amount of hypo required in the first developer. The absolutely worst thing is to try to vary more than one variable at a time.

 

[destroya]

the only film i have had luck with with no hypo is foma 100. Mr red is a reversal expert, hopefully he'll chime in

 

[iandvaag]

In my (albeit limited) experience with reversal processing, the theory is not too complicated once you get it figured out. In a traditional reversal process, all steps are "to completion" except for the hypo in the first developer. Highly active (ie: paper developers) are used quite concentrated (I use dektol 2+1) and the development part of the first developer goes to completion as well. Even with this very active development, many B&W films have excess silver, and highlights will not be clear, even though essentially every part of the film that has had any exposure is developed. Thus, to get good Dmin, you need a silver halide solvent (eg: hypo) somewhere in your process. The amount of time/concentration combination of hypo to obtain clear highlights is a constant for a certain film stock/EI combination. This "clear highlights by hypo" step can be performed in a separate bath instead of incorporated into the 1st developer, as the two processes are largely independent of one another. The advantage of separating this step as another bath is that it can be performed by inspection. Once you determine the correct amount of time/concentration for a particular flim stock/EI combo, you can re-incorporate the proper concentration of hypo back into the first developer. As far as I understand it, you will not approach hypo's capacity as fixer in this application, so you can trade off concentration for time linearly to determine the concentration of hypo needed to just clear the highlights in 12 minutes (ie: time of the first developer bath).

If you want acceptable results, without too much experimentation, keep it simple as Gerald suggested and stick to Ilford's recommendations. In any case, make sure you measure carefully and use the correct temperatures. I HIGHLY recommend using distilled water for the bleach and the washes before and after. Permanganate bleach is a super oxidizing agent, and you risk manganese dioxide stains on your film if there are minerals in your water.

PS I would just like to say that it is widely reported that Ilford's permanganate bleach is too strong and softens the emulsion unacceptably. I use 1g/L potassium permanganate for 5 minutes (to completion.)

 

[iandvaag]

This is just a theory, but I would say it's best to err on the side of not enough time/concentration of hypo. If you find after you develop your film that the highlights are not clear, I theorize (not tested) that you would be able to use a rehalogenating bleach (ferricyanide with bromide) to convert the black metalic silver back into silver bromide, then use some more dilute hypo to clear the highlights (reduce the amount of silver bromide) some more, and then redevelop. (Or alternatively sulphide tone for sepia slides).

 

[Gerald C Koch]

Yes, permanganate and copper bleaches soften emulsions. Some films are more effected than others. However with the difficulty in obtaining potassium dichromate, potassium permanganate may be the only bleaching agent available.

 

[SalveSlog]

Any particular reason why you left out the hypo?

I just want to learn (by doing in addition to reading) about the variables. I will eventually use hypo for HP5+, and then I will really learn what it does!

To Gerald:
As I've stated in other threads: I have great respect for the Ilford paper and have followed it to the letter with Delta and FP4+. I was ecstatic about the result since I had read David Wood (dr5) claim on his website that it was no good. And I really did not expect that little me could do it.

But, probably mostly because I like contrasty subjects I had to adjust both the iso a little and the development time (to 10 minutes) to not blow out the highlights. Adjustments of these two variables is suggested by the Ilford paper.