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  1. #21
    Dean Williams's Avatar
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    Quote Originally Posted by dancqu
    As Sue has likely not the foggiest idea of the quantity of working
    strength fixer needed to process a roll of film, your suggestion
    may be the way for her to go.

    I use fixer one-shot very dilute. I have by testing determined
    the quantity of chemistry needed then dilute to the
    necessary volume. Dan
    dancqu, the reason I suggested that Sue use her fixer undiluted is because that's how the manufacturer intended it to be used. Not because I thought she didn't understand that it could be used "highly diluted"...it cannot. The stock number she gave for the fixer she has on hand is for Kodak powdered fixer. It's mixed according to directions on the package, and used as mixed. Diluting this fixer even 1+4, (not a high dilution when compared to other fixers), would have one fixing films for half an hour or more, and who knows how long for FB papers.

    I too, would like to hear your testing methods for determining fixing times for "very dilute" fixers, how you tested for residual silver, how long materials are fixed, and what brand of fix you are using. Suggesting that fixers can, or should, be used at a dilution higher than the manufacturer's recommendation deserves some documentation, in my opinion.
    [COLOR=Sienna][FONT=Arial]Some days are diamonds. Some days a tree crashes through your roof.[/FONT][/COLOR]

  2. #22

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    Quote Originally Posted by Dean Williams
    Diluting this fixer even 1+4 ... would have
    one fixing films for half an hour or more, and who knows how long
    for FB papers.

    I too, would like to hear your testing methods for determining fixing
    times for "very dilute" fixers, how you tested for residual silver, how
    long materials are fixed, and what brand of fix you are using.
    I did point out to the OP that I use the diluted fixer one-shot.
    At start the fix is fresh; new fix. Times for film and paper in S. or A.
    Thiosulfate have been about what one would allow when using a usuall
    fix. As it turned out there was'nt much to the conventional wisdom with regard to long fix times when using very dilute fixers. I don't have any
    well used but still good fix on hand to compare.

    Assurance of a good fix with film is the usuall clear colorless base
    and an iodide test of the used fix showing some remaining capacity.
    I suppose one could make a double size solution and with another
    roll of film do a twice clearing time test.

    There are three tests for paper; the iodide test on the fixer, the
    sulfide or KRST test on the paper, and the post fix/wash
    redevelop test.

    I'm not a fixer peddler. I'm just pointing out that fixer can be used
    at nearly any dilution just as long as there is enough of what does
    the fixing, in the solution. I use all chemistry one-shot and that
    works very well with the one tray used when printing. Dan

  3. #23
    Helen B's Avatar
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    'Assurance of a good fix with film is the usuall clear colorless base
    and an iodide test of the used fix showing some remaining capacity.
    I suppose one could make a double size solution and with another
    roll of film do a twice clearing time test.'


    Dan,

    From your description, I presume that you don't require archival standards. The two criteria you mention do not ensure that there is no complexed silver remaining in the film. Is that a fair assessment? Your tests for paper are also only qualitative rather than quantitative.

    I am interested to learn a few more details - like typical dilutions, volumes at working strength and times.

    Thanks,
    Helen

  4. #24

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    Archival standards. I've just looked at Dr. Gudzinowicz post at
    www.binbooks.com which includes G. Haist's table of commercial and
    archival safe fixer capacities.

    There are errors in that table which Dr. G. may have introduced, typos?,
    while posting. I don't have Haist's book. You might take a look at the
    doctors post to confirm.

    Ilford has another standard. I'll study Martin Reed's coverage of
    the subject and then get back to you. I'm about to start a new series
    of fixer experiments.

  5. #25

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    Quote Originally Posted by Helen B
    'Assurance of a good fix with film is the usuall
    clear colorless base and an iodide test of the used fix showing
    some remaining capacity. I suppose one could make a double
    size solution and with another roll of film do a twice clearing
    time test.'


    Dan,

    From your description, I presume that you don't require archival
    standards. The two criteria you mention do not ensure that
    there is no complexed silver remaining in the film. Is that a fair
    assessment? Your tests for paper are also only qualitative
    rather than quantitative.

    I am interested to learn a few more details - like typical dilutions,
    volumes at working strength and times.

    Thanks,
    Helen
    A standard is some maximum level of silver per liter and some
    maximum level of residual silver left in the paper or film. What you
    are saying is that the standard darkroom tests I've mentioned
    are in no way quantitative and imply they are of no value
    when evaluating the fixer, film, or print. So now we've
    no way of knowing. What do you suggest?

    I suggest that in fact the mentioned tests are very quantitative.
    I doubt there are any tests purely one or the other. A hint of color,
    a barely perceptable haze, zero stain, coupled with the iodide test
    which is a titration method for quantitatively determining the
    amount of silver present, each of those tests contains
    usefull information and all togeather a LARGE AMOUNT.

    Dilution and volume examples:
    For Pan F 120; 20 ml of 60% A. Thio. in 500 ml total, 1:24.
    For paper 8X10; 1/4 oz of same in 250 ml total, 1:31.
    I've also the above information for S. Thio. Dan

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