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  1. #11

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    Quote Originally Posted by mhv
    Actually that's an interesting thought: can you dilute
    normal fixer to the minimal amount required for a film
    and use it without problems?

    For instance, my bottle of Kodafix says that 3.8L of 1+3
    diluted solution will fix approximately 120 rolls of 620 film
    (hello Kodak, time to change the labels!). Provided that
    I need 500ml to fill my daylight tank for 1 roll of 120,
    I could fix approximately 15 rolls of film with that
    amount of fixer at this dilution.

    If I reduce the dilution of my fixer by a factor of 15, i.e.
    moving from 1+3 to 1+45, then I could use ~10-15ml of
    fixer in 490ml of water to have a one-shot fixer.

    Does that make any sense?
    That does make sense. Exact amounts likely will need
    adjustment. First of all Kodak is probably averaging when
    arriving at that 120 rolls. If so, how much averaging, fudging,
    are they doing? Allowing for worst case, little or not
    exposed rolls, may reduce Kodak's 120 to perhaps 80.

    Whatever the exact amount, which I came very
    close to by 'pinking' two rolls of Pan F+, I think some
    little surplus is good to have. No doubt fixation slows
    considerably as the fixer nears exhaustion.

    You'll know by testing just how much averaging is being
    done. There are not any 'magic' strengths. Thick brew
    fixers are used with film because of film's great
    tolerance for silver held in solution. That, BTW,
    is a BIG PLUS for highly dilute fixer, archival
    silver levels are not exceeded.

    Running very late. I'll add some how-to today. Dan

  2. #12

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    Quote Originally Posted by dancqu
    ... some how-to ...
    I arrive at working strength by the splits method.
    If I were to bring a liter of A. Thio. concentrate into
    stock it would go into 4, 1/4 liter bottles. Any shortage
    in volume is made up with distilled water.

    A 1/4 liter will be split to 4, 1/16. Splitting a 1/16 into
    3 one ounce bottles allows enough for three rolls of film.

    One or more rolls or one or more sheets at one time may
    be one-shot be processed. Stop bath is superfluous
    when using one-shot fixer. One-shot developer,
    why not one-shot fixer? Dan

  3. #13
    Michel Hardy-Vallée's Avatar
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    Dan, do you calculate the strength of the fixer based on a dip test with a strip of film, or are these calculations based on the manufacturer's recommendations?

  4. #14

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    Quote Originally Posted by dancqu
    I arrive at working strength by the splits method.
    If I were to bring a liter of A. Thio. concentrate into
    stock it would go into 4, 1/4 liter bottles. Any shortage
    in volume is made up with distilled water.

    A 1/4 liter will be split to 4, 1/16. Splitting a 1/16 into
    3 one ounce bottles allows enough for three rolls of film.

    One or more rolls or one or more sheets at one time may
    be one-shot be processed. Stop bath is superfluous
    when using one-shot fixer. One-shot developer,
    why not one-shot fixer? Dan
    I agree, Dan. That's what I've done with the last several rolls of 120 I processed.

    I used a fluid ounce of 60% ammonium thiosufate. I believe that an ounce of anhydrous sodium thiosulfate would also work well as a one shot for a roll of film.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  5. #15

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    Quote Originally Posted by mhv
    Dan, do you calculate the strength of the fixer based
    on a dip test with a strip of film, or are these calculations
    based on the manufacturer's recommendations?
    Calculating won't do it. Real world testing is needed.
    I decided unexposed rolls of film are needed for testing
    because I've no intention of adjusting the strength of the
    fixer for each and every roll of film. But if one were to
    process several rolls of same exposed film, then a
    more exact strength could be used.

    Take Pan F+ for example. I lowered the amount of S. Thio.
    penta to 15 grams and had pink, unclear film. At 18 grams,
    better results. At 21.5 grams penta, 15 grams anhydrous,
    I could see no color and had a very clear film base. With
    that amount I was allowing 12 minutes; the first two
    constant then each minute a few seconds agitation.

    If I use S. Thio. in the future I'll likely up the amount a
    bit for a 10 minute fix and a little more margin. All that
    is for unexposed Pan F+ 120 film. None of the silver
    halides in the emulsion have been reduced so the
    entire amount must be fixed out.

    IIRC the a iodide test will work but the fixer is so highly
    dilute only a haze of a precipitate will be produced. After
    all only archival levels of silver are present.

    If some small allowance has been made a short strip of film
    will clear. Also, the sulfide test can be made, no stain no
    silver. By the same token an expose and develop test
    can be done. As for myself colorless crystal clear film
    and a positive test using iodide is enough for me.

    Likely there are big differences twixt the various films
    in the amount of chemistry needed. Just guessing I'd think
    Tri X might need 50% to 100% more than the Pan F+
    and T & D films as much more. Dan

  6. #16

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    A one gram correction. Second paragraph: At 21.5 grams penta
    should read, At 22.5 grams penta . Dan

  7. #17
    Michel Hardy-Vallée's Avatar
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    Hi Dan, I'm working so far only with pre-mixed fixer solutions like Kodak's or Ilford, so that's why I wasn't sure how to adapt your methodology. I've made the test of putting a small strip of film in fixer at the recommended dilutions to see how long it takes to clear, but that's the furthest I mananged to go. I'm not really going into doing my own chemicals, so I'd need a procedure that calibrates with commercial products.

    Cheers,
    Michel

  8. #18

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    Quote Originally Posted by Tom Hoskinson
    I agree, Dan. That's what I've done with the last
    several rolls of 120 I processed.

    I used a fluid ounce of 60% ammonium thiosufate.
    I believe that an ounce of anhydrous sodium thiosulfate
    would also work well as a one shot for a roll of film.
    As you've likely read my most recent post dealing
    with some of the details of using sodium thiosulfate,
    I'll not repeat.

    Certainly an ounce will do for some films, very
    probably any of the non T or D through ISO 125
    and perhaps even the 400s.

    I've not had the anhydrous or penta on the shelf
    very many years but think the S. Thiosulfates may be
    good indefinitely.

    I'll make an exception with the S. Thiosulfates.
    Although I do not at present, I'll suggest the spoon for
    those who would like to have a quickly prepared fresh
    fixer for their film, or paper for that matter. Any
    scale good for ounce or better weighings can
    be used to determine the average gram
    weight of a spoon's worth. Dan

  9. #19

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    Quote Originally Posted by mhv
    Hi Dan, I'm working so far only with pre-mixed fixer
    solutions like Kodak's or Ilford, so that's why I wasn't
    sure how to adapt your methodology. I've made the test
    of putting a small strip of film in fixer at the recommended
    dilutions to see how long it takes to clear, but that's the
    furthest I mananged to go. I'm not really going into
    doing my own chemicals, so I'd need a procedure
    that calibrates with commercial products.
    What you want are some pointers towards one-shot
    usage of off the shelf fixers. Worst case, an unexposed
    roll of any one film, will need a certain minimum amount
    of chemistry to complex with all the silver halides. For
    best mileage work close to that minimum. You'll need
    to test for that by fixing two or three rolls of same
    type unexposed film.

    I don't know which 120 film you use but for starters
    try one ounce per roll of your concentrate in whatever
    solution volume needed. I've been using 2/3 ounce of
    unadulterated, P. Formulary 60% A. Thio. for my 120
    Pan F+. Perhaps Tom H. will tell us with which films
    his one ounce amounts have worked.

    Off the shelf rapid fixers have added preservative and
    ph adjustment chemicals. It is safe to assume that
    from one make and model to another there is
    some varying of capacity.

    I'm sure you'll like your fixer one-shot once you've the
    hang of it. Don't forget to skip the stop. Dan

  10. #20
    Michel Hardy-Vallée's Avatar
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    Quote Originally Posted by dancqu
    What you want are some pointers towards one-shot
    usage of off the shelf fixers. Worst case, an unexposed
    roll of any one film, will need a certain minimum amount
    of chemistry to complex with all the silver halides. For
    best mileage work close to that minimum. You'll need
    to test for that by fixing two or three rolls of same
    type unexposed film.

    Ok, it's exactly for that that I lack a proper procedure. I would base my minimum amount on a calculation from the manufacturer's recommendation, but experimentally speaking, what can I use to determine if my fixer is already exhausted after a roll?

    BTW, why skipping the stop? Does it exhaust fixer as well?

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