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  1. #21
    rjr
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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/Foto...nam=cernob_fot

    And the film:
    http://www.foma.cz/foma/produkt/Foto...nam=cernob_fot
    Tschüss,
    Roman

  2. #22

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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.

  3. #23
    Helen B's Avatar
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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

  4. #24
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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 Helen B; 09-27-2004 at 11:47 PM. Click to view previous post history. Reason: Clarification of EK MP chemistry

  5. #25
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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?

  6. #26

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    Hi David, I would also be interested in knowing specifically what differences in image quality you see for permanganate vs. dichromate bleaches, since yours is the first mention I have read of a final image quality difference between these two bleaches. Is it grain or tonality or something else?

    Oxidizers like permanganate and dichromate are usually toxic but some are more toxic than others. Rather than a quack remedy, permanganate seems to be pretty commonly used in dilute solutions as a treatment for athlete's foot and other related skin infections. Wouldn't want to do that with chromium salts... Cr(VI) is certainly fine to use when handled correctly -- OTOH I agree with you David that many people are not likely to handle it correctly.

  7. #27
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    This doesn't seem to be the first time I've heard of potassium permanganate used for medicinal purposes - as an antiseptic (??).
    Any "Medical Types" out there who can confirm or reject?

    P. S. Potassium Ferricyanide - I've heard various comments about its "harmfulness" . The bottle I have does not carry a "Poison" label... the only chemical in my darkroom that does is Kodak Indicating Stop Bath (acetic acid), and I'm serously thinking of going to diluted white vinegar when I run out.
    Carpe erratum!!

    Ed Sukach, FFP.

  8. #28
    Helen B's Avatar
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    David,

    I mentioned permanganate baths as an aside - I have good memories of what appears to be a weird application to people who are unfamiliar with it. I didn't expect to be called 'nuts' or to be told that it blew my credibility. As you perceive it to be such a contentious issue, and still persist in using it to question my sanity, I'll go off topic for a while.

    I have read the MSDS for permanganate. What made you think that I hadn't? Don't I come across as someone who does her homework? The MSDS refers to the dangers of comparatively high concentrations of permanganate. Typical therapeutic baths are 1 to 10 000. Manganese is not accumulated in the body. Fish can survive swimming in dilute permanganate though they mustn't be in it long enough for the manganese level in their blood to rise to heart-stopping levels - it's used in vetinary medicine as well.

    There is plenty of evidence that shows that the worst effect of bathing in dilute permanganate is a fake tan - hey, you might be mistaken for a Californian. In cases of acute infection with inflammation of your entire skin (ie your whole body is covered in oozing sores) permanganate baths are a rapid and effective route to normality. Or near-normality in my case.

    Back to the subject at hand.
    'I know its the best development for B&W available.'
    When I get home tonight I'll post a comparison between some TXP you processed and some I processed.

    I didn't find your comment insulting, and I didn't say that I was insulted. Your comment said more about you than it did about me. I just thought that personal remarks were out of place in a discussion like this, so I suggested that you avoided them. It's no big deal.

    Best,
    Helen

    Later edit, in reply to Ed's question:

    Quick quotes from

    Principles of Pediatric Dermatology:

    Potassium permanganate compresses
    These are used in different concentrations. Potassium permanganate compresses in concentration of 1:9000 are used by clean gauze moisten with the solution and applied repeatedly to the skin lesion for 10 minutes every four hours. When the gauze is dry it should be moistened again and repeated application each time is necessary.
    The brown staining of the skin can be removed with lemon juice.

    Wet dressings
    Wet dressing is used as a soothing and cooling antiseptic on dry inflamed skin lesions as in oozing eczema.
    Potassium permanganate is an effective and widely used dressing. Potassium permanganate five grains added to 3 qt make a solution of 1: 9000 concentration is an optimum wet dressing to dry oozing lesions as in acute dermatitis.


    and the Oxford Handbook of Sports Medicine, in reference to athlete’s foot: Soaks should be lukewarm and contain potassium permanganate 1 in 10 000 and the feet immersed in the solution for 15 minutes three times daily.

    Plenty more if you want...

    I’m not sure whether I bathed in 1 : 10 000 or 1: 9 000. The nurses just told me to ‘put enough in to give a purple colour, and stay in for half an hour’. I was in a hospital in S E Asia for people with communicable diseases, and the nurses definitely didn’t want whatever it was that I had, so they pretty much left me to it. Remarkable how quickly you can learn to do an intravenous drip when it’s you that needs it.
    Last edited by Helen B; 09-28-2004 at 11:59 AM. Click to view previous post history. Reason: Medical information added in response to Ed's question.

  9. #29
    Helen B's Avatar
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    One of my recent posts has gone missing - lost during problems with the server? Here it is again, more or less.

    Some information from Agfa that sheds some light on the issue:

    When processing black-&-white reversal films and in micrographics and the graphics sector, the developed silver is bleached with bleaching baths which contain a strongly acidic potassium dichromate solution containing approximately 7.5 g of K.sub.2 Cr.sub.2 O.sub.7 /l as the oxidising agent. A soluble silver salt, for example silver sulphate (Ag.sub.2 SO.sub.4), is formed during the bleaching operation, and is rapidly washed out of the photographic layer.

    It has become important on environmental grounds to reduce the quantity of dichromate or, preferably, entirely to avoid bleaching baths containing dichromate.

    Substances having a similarly high electrochemical oxidation potential as dichromate, such as for example salts of tetravalent cerium, heptavalent manganese, trivalent iron and persulphate solutions are not suitable because, even at elevated concentration, they oxidise metallic silver only slowly (bleaching times of more than 10 minutes) or because, as in the case of heptavalent manganese, while they are indeed sufficiently active, they are so unstable in solution that they decompose after a short time and deposit manganese dioxide on the tank walls, in the hoses, on all equipment components and on the belts.

    Combining the stated oxidising agents with known bleaching accelerators, for example thioglycerol, is also unsuccessful because bleaching times still remain above 10 minutes. Moreover, this method requires an additional bath (prebath) because sulphur compounds such as thioglycerol are immediately oxidised by the oxidising agent in a combined bath and thus rendered ineffective.

    The object of the invention was accordingly to provide a bleaching bath for black-&-white silver halide materials which allows bleaching in a reasonable time (<10 minutes), is stable, may be used in continuous regeneration operation and contains at most 3.4 mmol of dichromate/l. The bleaching bath should preferably contain no dichromate.

    This object is surprisingly achieved by the combination of at least 2 oxidising agents having an oxidising potential of .gtoreq.500 mV, optionally together with a metal salt having a stabilising action of a metal of subgroups 1 or 2 of the periodic system of elements, wherein, in the event that dichromate is used as one of the oxidising agents, it is used in a quantity of at most 3.4 mmol/l.

    Suitable oxidising agents are, for example, persulphates and metal salts in elevated valence states.

    Suitable persulphates are, for example Na.sub.2 S.sub.2 O.sub.8, K.sub.2 S.sub.2 O.sub.8 and (NH.sub.4).sub.2 S.sub.2 O.sub.8.

    Metal salts having an elevated valence state are, for example, salts of tetravalent cerium, heptavalent manganese and trivalent iron.

    Metal salts of subgroups 1 and 2 are, for example, AgNO.sub.3, CuSO.sub.4, ZnSO.sub.4 and CdSO.sub.4. Surprisingly, these metal salts stabilise permanganate solutions, for example, so suppressing the formation of manganese dioxide.

    The persulphates are in particular used in a quantity of 0.001 to 0.5 mol/l, preferably of 0.01 to 0.1 mol/l.

    The metal salts having an elevated valence state are in particular used in a quantity of 0.001 to 0.2 mol/l, preferably of 0.01 to 0.1 mol/l, wherein, as stated, the quantity of dichromate does not exceed 3.4 mmol/l.

    The metal salts of subgroups 1 and 2 are in particular used in a quantity of 10.sup.-1 to 10.sup.-4 mol/l, preferably of 5.multidot.10.sup.-2 to 5.multidot.10.sup.-4 mol/l.

    The bleaching bath according to the invention in particular has a pH value of 0 to 2, preferably of 0.1 to 1.5.

    In order to shorten the bleaching time, an upstream bath with a bleaching accelerator, for example thioglycerol or 3-mercapto-1,2,4-triazole, may be used. This bath preferably contains the compound containing sulphur in a quantity of 10.sup.-4 to 10.sup.-1 mol/l.


    etc

    It's from US patent nr 5,716,767 and the full text can be found by searching on the patent number at http://www.uspto.gov/patft/index.html

    You might also like to do some searches like

    (an/agfa-gevaert or an/agfa) and ((abst/black and abst/white) or abst/reversal)

    which means applied for by Agfa or Agfa-Gevaert and containing 'black' and 'white' or 'reversal' in the abstract. I think.

    Anyway, reading that got me thinking - why was I not having problems? I'm guessing that the answer is down to using inversion processing in small tanks and using fresh solutions for the bleach and the clearing baths. Less carry-over. Constant, brisk agitation.

    Best,
    Helen

    Later edit: If you look at the full text of the patent, or better, the image of the patent, you will see the results of tests that Agfa carried out with various formulae on developed APX100. The formula, time and final density are given.

    Patent 6,350,563 also gives quite complete details of a process (need not be the process) for 'A commercially available black-and-white reversal film, e.g. that of film speed 200 supplied by Agfa-Gevaert AG'. While one wouldn't want to copy these, there is useful background information.
    Last edited by Helen B; 09-29-2004 at 07:01 AM. Click to view previous post history.

  10. #30

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    or because, as in the case of heptavalent manganese, while they are indeed sufficiently active, they are so unstable in solution that they decompose after a short time and deposit manganese dioxide on the tank walls, in the hoses, on all equipment components and on the belts.
    Anyway, reading that got me thinking - why was I not having problems?

    I think there is your answer, apparently if you use permanganate with fresh solution as a one shot deal you can use it. I am sure this would not be desirable for commercial operations but seems to work for us lab rats.

    OTOH on the book I was telling you (Developing) they use permanganate solutions as bleach, so it might not be as unstable as Agfa seems to think.

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