Permanganate reversal baths

Discussion in 'B&W: Film, Paper, Chemistry' started by Helen B, Sep 21, 2004.

  1. Helen B

    Helen B Member

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    Curiosity; a bit of a rambling question...

    Simple question: does anyone know of a reason not to use a permanganate reversal bath after a first developer that contains thiocyanate/-ide/sulphocyanate/thiocyanic acid/rhodanide/KSCN/whatever-you-want-to-call-it? There's a good wash inbetween of course.

    Back in the thirties the Dufaycolor process (B&W emulsion and chemistry despite the name) did exactly that (thiocyanate followed by permanganate), but I've found no recent reference. Example: Kodak specifically say (publication H24, module 15, page 25) that D-94 (which contains thiocyanate) should not be used as a first developer with R-10, which is a permanganate reversal bath. D-94 was designed for use with R-9, which is a bichromate reversal bath - now unacceptable for environmental reasons. As far as I can tell, it isn't because of the acidity of R-10, because R-9 also had a low pH. Is this one of those blindingly obvious reasons that I miss?

    It's just curiosity - there are plenty of good alternatives for the first developer that don't use thiocyanate.

    While I'm rambling about reversal processes: I'm also looking at fogging developers as second developers - with or without a reversal exposure (no reason not to do both). Good old T-19 sulphide toner seems to work quite well, giving sharp images with low graininess and lovely tonality (at least to my taste). Next on the list to try is KRST, then my next thought is colour developers (the colour of the film image is not important to me). Any other suggestions? I don't think that I'll be trying FD-70a or FD-72.

    Thanks,
    Helen B-49
     
  2. Jorge

    Jorge Inactive

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    The only thing I can think of is the effect of the different bleaches. Permanganate being more of a proportional developer and dichromate more of an overall bleach. It most like has to do with the quality of the results rather than the possibility of any chemical reaction.

    Actually in the book "Developing, a focal manual of Photo-Technique," Jacobson & Jacobson list several formulas with thiocyanate followed by a permanganate bleach. Of course this is an old book, so I am sure there might be another reasons for more modern processes.
     
  3. gainer

    gainer Subscriber

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    The iron stain remover, trade name "Iron Out", is a good fogging agent. I haven't played with it for a while, but I think it works well with a little added carbonate. I don't have the bottle before me, but IIRC it is sodium hydrosulfite.
     
  4. Jordan

    Jordan Member

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    Helen,

    If you use a good stop bath after the first dev you should be okay. I can't think of an adverse reaction that permanganate in acid would cause but dichromate in acid wouldn't.

    For fogging agents -- Pat Gainer's advice sounds really interesting -- otherwise there is stannous chloride or sepia toner. KRST in itself is not going to be enough to reduce un-exposed silver AFAIK, although if you did a conventional light re-exposure followed by re-development, you could tone the resulting silver positive image with KRST and get a nice archival B&W positive. I have read speculation that one of the final steps in the (proprietary) Agfa Scala process is a selenium-toning step.

    With a sepia toner fogging agent, I noticed some pretty strong film effects. I used a thiocarbamide-based toner mixed up in a proportion that would give pretty cold browns in regular paper toning. I tried reversal processing some TMX and PanF at the same time in the same soup -- the PanF gave a beautiful cold brown tone while the TMX gave sickly yellows. This must have to do with grain size and shape etc.

    I've given much thought over the years to B&W reversal, trying to get it to work with regular B&W chemistry as much as I can. I have a workable first developer recipe based on HC-110B. Send me an e-mail if you want more info.
     
  5. Helen B

    Helen B Member

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    Thanks Jorge, Patrick and Jordan.

    I found 'Super Iron Out' which is sodium bisulphite and hydrosulphite according to the MSDS.

    Some notes I made ages ago include this as a fogging developer. I have no idea where I got the formula from:

    Propionic acid 15 ml
    Stannous chloride 2 g
    Sodium hydroxide 5 g
    Water to make 1 litre

    Jordan,
    Have you tried any paper developers, with or without added thiocyanate or thiosulphate?

    Once again, thanks for your contributions.
    Best,
    Helen
     
  6. mobtown_4x5

    mobtown_4x5 Member

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    Helen-

    When you have settled on a reversal process that seems to work well, would you mind sharing detailed instructions/formulae? I have long been interested in using reversal to enlarge negs.

    Matt
     
  7. sanking

    sanking Member

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    If you are interested in making enlarged negatives by reversal look at the article at http://unblinkingeye.com/Articles/NbyR/nbyr.html and at links to Liam Lawless.

    I have personally switched to digital enlarged negatives but I used Liam's reversal processing method for a number of years and can assure anyone interested in wet processing that it gives outstanding results.

    Sandy
     
  8. Helen B

    Helen B Member

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    Matt asked 'would you mind sharing detailed instructions/formulae?

    I like sharing... but I doubt that I'd come up with anything that hasn't been published already. None the less I'm happy to post my results. Don't hold your breath though - I have to sneak all this kind of stuff in edgeways.

    Sandy,
    Thanks for the link. I think that I've read everything on unblinkingeye, but it's good to be reminded of what's there, and to read your experience of Liam's method.

    Best,
    Helen
     
  9. sanking

    sanking Member

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    BTW, I see that the link to Liam's article is dead. The original information by Liam, which is quite detailed, was published in two articles in Judy Seigel's Post-Factory Photography some years ago. It is the best information I have seen anywhere on reversal processing and although Ed Buffaloe's article follows Liam's method rather closely, the original articles are still well worth reading.

    Sandy



    Sandy
     
  10. Helen B

    Helen B Member

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    I downloaded Liam's original article a while ago, but I have no idea which country my copy is in, never mind which disk it is on.

    I hope that people change from a bichromate bleach to a permanganate bleach (and a compatible clearing bath - the clearing bath should be chosen according to which bleach is used).

    Best,
    Helen
     
  11. Jordan

    Jordan Member

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    Helen -- I've never tried packaged paper developers -- I don't print at home so I don't keep them at hand. But Ilford has a PDF on their site about reversal processing that starts from Bromophen or PQ Universal to make a first dev.

    Jordan
     
  12. Helen B

    Helen B Member

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    Jordan,

    Yes, it's quite common to use a paper developer. Maco suggest their LP-BROM 4 for reversing PO100c, for example

    Best,
    Helen
     
  13. Jordan

    Jordan Member

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    Right, I think I've seen MACO's instructions too. BTW, check your e-mail for my reversal info.
     
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  15. wdemere

    wdemere Member

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    I just noticed that to buy Potassium Dichromate you have to have a DEA Authorized Buyer Form on photographers formulary, though I'm not sure if I need a DEA registration number.

    Has anyone else run into this? Is there somewhere to buy the kit already made up?

    Thanks,

    William
     
  16. Helen B

    Helen B Member

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    Why not just switch to a permanganate reversal bath?

    Best,
    Helen
     
  17. wdemere

    wdemere Member

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    You need the form for sulfuric acid too. Wierd. I don't think you need a DEA registration though.

    William
     
  18. Jordan

    Jordan Member

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    Sulfuric acid is pretty nasty stuff. Battery acid is sulfuric acid and may be easier to find locally. IIRC the strength of sulfuric acid in a typical bleach bath is around 2%. You could use sodium bisulfate (note: not sodium bisulfite) as a substitute -- it is a solid that dissolves in water to produce what is effectively a sulfuric acid solution. But it may be expensive or hard to get.

    FWIW, here is my first-dev recipe based on HC-110 (slightly ad-hoc as shown by the mixed units):

    Start with about 400 ml water and add:

    6 tsp sodium carbonate
    15 ml HC-110 syrup (concentrate as sold in North America)
    2 g potassium bromide (anti-fogging agent -- may not be necessary)
    8 g sodium thiosulfate
    make up to 500 ml in water

    I found that 8.5 mins at 24C gave good results (E.I. ~64) with Ilford Pan F Plus using a permanganate bleach, metabisufite clearing bath and thiocarbamide re-fog.

    Jordan
     
  19. rjr

    rjr Member

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    Helen,

    If you ever find it again, would you mind sending me a copy?

    I recently worked on an instruction sheet for developing Agfa Scala in the commercial Foma Slide kit (works very decently!) and plan to give a from-scratch approach a try.


    Well - many people messed up the KMnO4 bleach... they prepare it too early and mix it with tap water, resulting in a reaction of the bleach with minerals in the water ("Braunstein") and thus spots on the film. Instead I´d recommend using demineralised water, mix is shortly before usage and to filter it. We had no problems at all after using this approach.

    Tetenal once sold a commercial slide kit - they changed it from dichromate to KMnO4 but made an error. It was sold premixed, the permanganate and the sulphuric acid came in a single pack and many people learned the hard way that this sometimes resulted in a nonfunctional bleach. Tetenal finally broke down and stopped selling the kit. :-(

    Thanks,
    Roman
     
  20. gainer

    gainer Subscriber

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    As a matter of interest, pHMinus for swimming pools is sodium bisulfate and is not very expensive.
     
  21. Jordan

    Jordan Member

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    Patrick, this is great to know. Thanks for sharing it. I may yet have another go at the B&W slide process at home.

    Roman, I didn't know that Foma made a reversal kit. That's also great to know. My chances of finding it for sale here in Canada are pretty much nil, though.
     
  22. rjr

    rjr Member

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    Jordan,

    Foma not only makes a reversal kit - they produce a _very_ decent reversal film in 35mm.

    Compared with Agfa Scala it is a bit softer in gradation, warmer in tone, albeit very sharp and with small grain. And it is quite cheap, you can get if the less than 3EUR per roll.

    The Foma film has a special AHU under the emulsion - it´s pretty tough to clear, looks very much like the mask a E6/C41 film has and it won´t clear in fixer or most reversal baths.

    If you guys care about I could translate the guidelines on using the process with Scala and Fomapan - it´s due for early October.

    The Foma kit sells for 13EUR in the Prague company shop and approx 20EUR in Germany (Fotoimpex, so probably J&C will carry it, too) and it is good for 8rolls per pack (probably more). It´s pretty much standard stuff - their Fomadon LQR developer (both for first _and_ second developing!), a clearing bath (Sodium BiSulfite), KMnO4-bleach and a the Foma rapid fix.

    Thats the information on the kit:
    http://www.foma.cz/foma/produkt/FotoDetail.asp?produktid=296&seznam=cernob_fot

    And the film:
    http://www.foma.cz/foma/produkt/FotoDetail.asp?ProduktID=14&seznam=cernob_fot
     
  23. Jordan

    Jordan Member

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    Roman, I had heard about the Foma reversal film. May be worth trying. I'll keep my eye open for the kit around here.
     
  24. Helen B

    Helen B Member

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    'While permanganate base bleach is a safer solution its results are less than stellar.'

    David,

    Have you found that the choice of bleach affects the quality of the final image? As it happens I spend a lot of time in the country, with no mains sewer - hence my interest in alternatives to dichromate in addition to my general curiosity about film processing. Your advice on converting hexavalent chromate to trivalent chromate is handy to know.

    I don't think that anyone would dispute the usefulness of many forms of chromium salts and chromates, but don't you think that there is a general trend to find replacements? Why else would Kodak change to permanganate bleach from dichromate bleach? Isn't there a trend in the metal finishing industry, for example, to move to chromate-free coatings, after the move from hexavalent to trivalent? These are actual questions, not rhetorical ones, by the way. I'm no expert.

    Thanks for your informed input.

    Best,
    Helen
     
  25. Helen B

    Helen B Member

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    'KODAKS CINE B&W reversal bleach is dichromate based.'

    Actually it was their switch to permanganate for the cine reversal process that triggered my question. The current version of H-24 module 15 specifically refers to a combination of D-94a and permanganate bleach (R-10) instead of R-9 dichromate bleach. That's what started all this discussion - it's there in the first post. There is an old D-94/R-9 document still lurking on Kodak's website however, as well as the current version. Last year (if I remember correctly, which I don't always do) Kodak issued H-661 that includes clear instructions on the process required to change from dichromate R-9 to permanganate R-10. I'm not making this up.

    EK do still supply a dichromate bleach in their packaged MP chemicals in the USA, I think, but they supply permanganate bleach in Europe. No comment.

    In what way is the permanganate bleach inferior to dichromate? I've not noticed any difference in the final results. I'm not saying you are wrong, I'm just asking what the difference is.

    'FYI i would'nt put Permanganate down your septic either. the iron might do damage to the metal parts of your septic system' Where does the iron come from? I agree that permanganate is best kept away from metal, and a few plastics for that matter.

    As ever, Kodak have very clear advice on the disposal of chemicals. Dilute permanganate solutions can be reduced safely by weak reducers like bisulphite and thiosulphate (how convenient) then neutralised with a weak acid. Strong reducing agents should be avoided.

    At the moment I'm just weighing up the options, finding out what I can and trying to satisfy my curiosity. I have no axe to grind any way. I'm very grateful for your willingness to share your view of things.

    An aside - my favourite use of permanganate: it's used for bathing in severe cases of skin infection. Half an hour immersed in a permanganate bath twice a day works miracles, and it doesn't seem to do the bath any harm.

    Thanks for the interesting discussion.

    Best,
    Helen
     
    Last edited by a moderator: Sep 28, 2004
  26. Helen B

    Helen B Member

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    Thanks for the reply. I haven't made up my mind, and I don't know where you got that impression from. I'll continue to do my own tests, because it isn't the comparison between your process and mine that is important, it is the comparison between permanganate and dichromate in whatever process I'm experimenting with. However, you have provided valuable advice, for which I thank you.

    I have film processed by you at the moment - I like it, there's nothing wrong with it. It's just that I want some slight tweaks to get the optimum results with the sort of thing I do. I'm not looking for a general-use process like yours, but a specific optimisation for a specific purpose.

    Bathing in permanganate. It happens, and it works amazingly well. I can speak from direct personal experience. It is definitely not a crazy idea.

    A friend of mine was talking to me about the differences between life in the US and in the UK. He's been here twenty years, I've been here two. The biggest problem he found was the difficulty of having a discussion on a subject he wished to explore. He felt that in the UK people realise that taking deliberately contrary stances leads to fruitful discussion and exploration, but that in the US if you take a contrary stance it gets understood that you are opposing the other person and battle lines are drawn.

    Once again, thanks very much for the information.

    Best,
    Helen
    PS Ditch the personal comments (like 'you remind me of a little kid') huh?