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  1. #1
    Ian Grant's Avatar
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    Filmotec/Orwo B&W Reversal processing

    First Developer ORWO 829
    Solution 1:
    Water (35°C) 750.0 ml
    Sodium sulphite 25.0 g
    Phenidone 0.2 g
    Hydroquinone 10.0 g
    Sodium carbonate 20.0 g
    Potassium bromide 6.0 g
    Potassium thiocyanate 6.0 g
    Solution 2:
    Water (20°C) 125.0 ml
    Sodium hydroxide 5.0 g
    After cooling down solution 1 pour
    solution 2 into it and

    Make up with water to 1 litre


    Bleaching bath ORWO 833
    Water 750.0 ml
    Potassium dichromate 10.0 g
    Sulphuric acid. conc. (caution) 15.0 ml
    Water to 1 litre


    Clearing bath ORWO 835
    Water 750.0 ml
    Sodium sulphite 90.0 g
    Water to 1 litre


    Second Developer ORWO 842
    Solution 1:
    Water (35°C) 750.0 ml
    Sodium sulphite 25.0 g
    Phenidone 0.2 g
    Hydroquinone 10.0 g
    Sodium carbonate 20.0 g
    Potassium bromide 6.0 g
    Solution 2
    Water (20°C) 125.0 ml
    Sodium hydroxide 5.0 g
    After cooling down solution 1 pour
    solution 2 into it and
    Make up with water to 1 litre


    Fixing bath ORWO 300

    Water 750.0 ml
    Sodium thiosulphate 5 hydrate 200.0 g
    Potassium Metabisulphite 20.0 g
    Water to 1.0 litre

    __________________________________________________ __________________________________
    Processing at 20°C:
    Times Minutes:Seconds

    1 First development (ORWO 829) 5:15 mins 20° ± ½°
    2 Washing -running ater 2 mins
    3 Bleaching (ORWO 833) 2 mins
    4 Washing - running water 1 min
    5 Clearing (ORWO 835) 1:30 mins
    6 Washing - running water 1 min
    7 Second exposure approx. 8.000 lxs
    8 Second development (ORWO 842) 2:40 mins 20° ± ½°
    9 Washing - running water 30 seconds
    10 Fixing (ORWO 303) 1:30 mins
    11 Washing - running water 3 minutes


    This process is designed for the Commercial Reversal processing of Filmotec Movie film. But should work well with any modern B&W film. You will need to experiment with the first development time and EI to find the best combination for your purposes.

    The First Developer & 2nd Developer are identical except for the Potassium Thiocyanate in the first.

  2. #21
    Ian Grant's Avatar
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    Ron (PE), the effects of overexposure at the reversal exposure are quite well documented, (of course it can happen with normal negatives as well), but I think it's harder to achieve with a tungsten light source, and you may not easily spot the early effects. All commercial processing lines of course use a controlled re-exposure, so it's virtually impossible under those conditions. However it will occur quite easily with re-exposure to daylight/sunlight, and at it's worst does cause Solarization.

    It's the blue/UV end of the spectrum that causes the damage, the residual silver halides left in the emulsion after first development and bleaching are effectively no longer Panchromatic, and their speed has dropped s significantly, they are now most sensitive to Blue/UV light and so 30 seconds to 4 minutes with a tungsten 100 - 275 watt bulb is in comparative terms very low compared to the same length of exposure to daylight or worse still sunlight. It could be a big mistake to do the reversal exposure in a room lit by daylight.

    Kodak actually use the same phenomenon for their direct reversal copying films, and Ansel Adams made his famous image with a black sun which demonstrates the effect very dramatically.

    I haven't spent much time on the direct reversal developers yet, but any of them will cause problems if the Silver Sulphates aren't fully removed, after the bleach bath. One function of the Sulphite or Metabisulphite clearing bath is to act as a wash-aid to help remove any semi-soluble silver salts from the emulsion, May & Baker's Reversal process actually used "Thiolim" their proprietary wash aid as the clearing agent.

    Ian

  3. #22
    Photo Engineer's Avatar
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    Ian;

    The conventional wisdom (not set in stone though) was that a first developer developed all of the exposed negative image and so there was nothing left to cause problems with the reversal exposure. And, that is why the re-exposure either via chemical means or light was considered to be going to completion!

    Now, I can agree with you, but in experiments I have never ever seen the re-reversal or solarization demonstrated via light or chemical means. This does not mean that it can't happen and the documentation you cite supports that. I think we have enough information betwee us to cause a warning flag for people to be cautions then. Thats about all I can say.

    Thanks.

    PE

  4. #23
    Ian Grant's Avatar
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    You need to think of the emulsion left after bleaching etc as Virgin emulsion. So it needs so much exposure to reach Dmax that and more is your exposure to completion.

    It's a bit like frying an egg, you might want the yoke runny so you pull it off the heat early, you might want it solid - that's our Cooking / Development to completion, you can keep going not a lot changes for quite a long time, then suddenly it's becoming burnt.


    So yes you expose to completion but that's been tested for.

    Ian

  5. #24
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    You might consider this then.

    The E6 color developer, after the fogging bath, is a developer that goes to completion. If there was virgin emulsion there that was not developed in the first developer, you would have a colored dmin. That was prima facia evidence in many reversal processes that the reexposure by any means went to completion. But that was also true in B&W.

    Since real B&W reversal process development was abandoned at many companies about 50 years ago, it seems that there may be a lot left to do.

    PE

  6. #25
    Ian Grant's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Since real B&W reversal process development was abandoned at many companies about 50 years ago, it seems that there may be a lot left to do.

    PE
    Fuji continued exploring the B&W reversal process well into the 80's. They looked particularly at the bleach baths to find a less toxic more stable alternative, these include two we didn't mention in a different post - one being Cerium. They also looked at some fogging agents we haven't touched on

    Agfa were still working in the same fields until much more recently, probably right up to their collapse. So there must still be improvements that can be made. It would be interesting to compare just how how much the last official Scala process differs from the Gevaert Formula for the early 50's Dia Direct films, which of course Agfa continued with after the merger and eventually evolved into Scala.

    Ian
    Last edited by Ian Grant; 12-17-2008 at 07:14 AM. Click to view previous post history. Reason: add

  7. #26
    Photo Engineer's Avatar
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    Ian;

    None of these came to fruition though. The only ones that I know of were the Kodak Persulfate bleach and I'm not sure how far that really went. Yes, there were copper bleaches and Ferric Citrate bleaches and Peroxide bleaches, as well as many fogging baths. There were even several organic bleaching agents developed and patented.

    I know of two new developer formulations that Kodak was working on as well, and Liquidol is the result of one approach doing the best I can without really exotic chemistry. None of these, in spite of research, truly went into the development or release stages at any company. The B&W reversal market was just not there.

    Even the E6 market has dried up pretty much, and that is why there has been no real change to the E6 process and product line for some years. Again, there were several improvements that died in the last 15 years or so.

    I would guess that if had analog continued to grow, there would have been a family of direct positive films that took a standard negative B&W process. The technology was there and that was the preferred direction with many in the field due to the simpler process and compatibility with the B&W neg-pos systems out there. High speed reversal emulsions eliminated the need for any bleach or clear bath entirely! No reversal step was needed either.

    PE

  8. #27
    Ian Grant's Avatar
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    Ron, I've just been sent something which clearly indicates Agfa had switched away from the Dichromate bleach by the middle of 2000, this matches the research data, which is quite detailed and extremely useful.

    "For approx. 6 months for the SCALA process a Bleach-bath is used, which no longer contains Dichromate and the replacement is ecologically substantially less precarious." It was in German so I've it's abit literal. Goes on to say Tetenal's B&W Reversal kit has also dropped Dichromate, this is in a communication from Agfa-Gevaert AG themselves, in January 2001.

    Ian

  9. #28
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    I believe it Ian, but I've never seen it here in the US, only the Kodak kit, and there was no mention of it at EK.

    It might be one of the persulfate bleaches or something like that. IDK.

    I do know that the US Bureau of Mines worked on refining silver ores to remove silver metal and silver salts and developed a series of what we would term bleach, blix and fix baths that were supposedly usable on depleted ores and were supposedly "friendly". I have tried a number of them that I gleaned from patents and other literature. They were not photographically useful IMHO.

    There is a whole body of unpublished (AFAIK) work on bleaches, blixes and fixes that were left dangling when projects were shut down, and one of the major players died suddenly. This was in the mid '90s.

    PE

  10. #29

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    It's a permanganate bleach. Used with precautions (very diluite) will not soften the emulsion too much.

  11. #30
    Ian Grant's Avatar
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    Quote Originally Posted by Alessandro Serrao View Post
    It's a permanganate bleach. Used with precautions (very diluite) will not soften the emulsion too much.
    Not sure which bleach you mean, Scala or Tetenal ?

    Agfa's research was into alternatives to Permanganate & Dichromate, and it was ongoing for quite a number of years and culminated in the change from Dichromate around 2000.

    I'll hopefully test the bleaches in the Spring, I still have a lot of reading to do and then need to analysi all the potential avenues to pursue. So far I have already made some important steps into gaining full control of the B&W reversal process.

    I'll keep you posted, I won't be keeping things secret.

    Ian

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