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  1. #11
    Mick Fagan's Avatar
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    In the Kodak C41 processing manual that I have, it's stated near the end of the bleach section, that bleach has an indefinite life.

    I myself have used a bleach regeneration process from Creative Darkroom & Photo techniques, since it was published in that magazine.

    I originally mixed up a litre of bleach and after usage I rehalogenate the bleach with a fish tank aerator for about 20 minutes or so. Then I re-adjust the pH using a small amount of acetic acid and it's ready to go again.

    After a while, one loses a bit of solution through natural attrition so I just mix up about 250ml of bleach and I'm off again.

    I've been doing this for years, it makes C41 so cheap to do this way.

    One of the things I did do after some experimentation was to use a weak stop bath after development. The idea is to stop development at a precise time, enabling one to then give the film a short 30 second wash after the stop before adding the bleach. This has had no visible effect on the films but has reduced the bleach requiring a pH adjustment by about 50% on a number of films put through the bleach before adjustment is required.

    I rotary process with a Jobo and lift.

    Mick.

  2. #12

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    Quote Originally Posted by Peter De Smidt
    Hi Nick. Do you use a Jobo? If so, what chemistry do you use?

    I don't really understand why Kodak recommends using the bleach only once in a Jobo, since bleach actually needs lots of oxygen to work properly. (I can see why the increased oxygenation (right word? I'm not a chemist) can cause problems for developer and to a lesser extent to fixer, but bleach?) I'm thinking of using the replenishment scheme that Kodak recommends for non-rotary systems. That would quadruple, or so, the amount of use that I'd get out of the bleach.

    What about fixer? Can I use it until Edwal Hypo Check says otherwise?

    I'm using Jobo 2500 type tanks but on a motorbase. The only difference I can think of is the speed the tank spins. But I doubt that matters enough.

    For C-41 I'm using Fuji mini-lab chemicals. I just repenish according to the Fuji specs. For both fix and bleach.

  3. #13

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    Quote Originally Posted by Nick Zentena

    For C-41 I'm using Fuji mini-lab chemicals. I just repenish according to the Fuji specs. For both fix and bleach.
    Nick, where do you get the Fuji-Hunt mini-lab chemicals from?

  4. #14

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    Quote Originally Posted by Mick Fagan
    In the Kodak C41 processing manual that I have, it's stated near the end of the bleach section, that bleach has an indefinite life.

    I myself have used a bleach regeneration process from Creative Darkroom & Photo techniques, since it was published in that magazine.

    [snip]
    Mick.
    Hi Mick, I appreciate your experience.

    Currently, Kodak says that their bleach has an 8 week life; and they say, in bold no less, "Do not attempt to replenish or regenerate used bleach solution. Reuse it only to batch capacity [which they elsewhere state to be about 4 120 films per liter]; then discard it. Also, do not reuse developr, fixer, or stabilizer. You must discard these solutions after a single use." This is from the current PDF on using Flexicolor chemicals with rotary-tube processors. I wish they'd tell use what their reasoning was. Clearly with developers the problem is excess oxygen introduction during processing.

  5. #15

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    Quote Originally Posted by Peter De Smidt
    Nick, where do you get the Fuji-Hunt mini-lab chemicals from?

    One of the local labs got a new machine. The new machine uses some sort of pre-packaged chemicals. I was in and he offered me the old stock. I offered 1/2 and he jumped up and down all happy. I was happy to-)

    Vistek locally carries the Fuji chemicals. Odds are somebody locally carries the stuff. Lots of mini-labs need it. Maybe if you know anybody running/working at a mini-lab you could ask if they'll order a jug for you?

  6. #16

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    Quote Originally Posted by Peter De Smidt
    Hi Mick, I appreciate your experience.

    Currently, Kodak says that their bleach has an 8 week life; and they say, in bold no less, "Do not attempt to replenish or regenerate used bleach solution. Reuse it only to batch capacity [which they elsewhere state to be about 4 120 films per liter]; then discard it. Also, do not reuse developr, fixer, or stabilizer. You must discard these solutions after a single use." This is from the current PDF on using Flexicolor chemicals with rotary-tube processors. I wish they'd tell use what their reasoning was. Clearly with developers the problem is excess oxygen introduction during processing.
    Do some tests yourself. I think that the fear is of some contamination affecting the solution, not the life of the solution itself.

    Graham

  7. #17

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    I just talked with Kodak's technical department. They say that the problem with replenishing bleach with rotary tube processing is the small amount of solution used. They recommend only 6- 120 films per liter. The problem, said Tony, is retained silver. Comments?

  8. #18

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    Since I reuse bleach and fix I only use the minimal amount of chemicals for developer. I think I've got 2litres of fix made and 1litre of bleach. When I process I use what I need then pour it back. Replenish the big bottle.

  9. #19
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    The bleach uses up the bromide, so aeration alone is not going to regenerate the bleach. It gradually loses activity through loss of bromide. It must be aerated and then fresh NH4Br must be added (ammonium bromide).

    The fix gradually is oxidized by the carryover of bleach into it unless you do a very thorough wash after the bleach and before the fix.

    Gradual build up of carryover fix into the stabilzer can cause dye stability problems.

    Drum processes are notorious for gradual carry over of one solution into another and this causes dilution and degradation of the chemistry.

    Since a pre-wet is recommended (or used to be by Jobo and Kodak both), the developer was diluted by the pre-wet and this was compounded if you reused the developer over and over. Also, there are seasoning effects in the developer due to released iodide and bromide. It is always best to discard the developer.

    So, in short, use developer one time and toss, use bleach till exhausted then aerate and replenish with some fresh or add NH4Br. I removed 100 ml and add 100 ml of fresh to each 1 L when I reach capacity.

    I do the same for my fix. Use to capacity, then remove 100 ml from 1 L and replenish.

    I use my stab and toss generally, but I have extended my wash to 2x and used the stab until it is exhausted, then replenished as above, 100 ml / liter.

    PE

  10. #20

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    PE,

    Thanks for your help. Kodak says (in their pdf on Flexicolor in a rotary processor) that one shouldn't use a pre-wet.

    BTW., what types of problems would retained silver cause? I'm not sure if Tony at Kodak meant retained silver in the emulsion or retained silver in the chemistry.

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