Fixer Procedure test

Discussion in 'B&W: Film, Paper, Chemistry' started by Timothy, Sep 24, 2008.

  1. Timothy

    Timothy Member

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    I saw a method posted somewhere in the last month or so, and I thought that I had downloaded a copy of it, but now I can not find it. I have tried searching for the original but I can not find that either. It had something to do with fixing unexposed bits of paper for varying times to determine the best time for full fixing. Can anyone please either explain the process or point me to the original post ? :smile:


    Thanks,
     
  2. bobwysiwyg

    bobwysiwyg Subscriber

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    Could it be this one?

    http://www.apug.org/forums/forum37/50296-exhausted-fixer-symptoms.html
     
  3. dancqu

    dancqu Member

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    ALL things being equal I've no doubt that the full fix times
    of various papers are not the same. BUT not ALL things are
    equal as fixers are ordinarily used. As the fixer is used it
    becomes loaded with silver and times increase. To
    compound the matter the type of emulsion silver,
    chloride or bromide and the relative amounts,
    will load at varying rates.

    Highly bromided papers will load a fixer sooner than one
    highly chlorided. The fixer will have less capacity
    and slow sooner. Dan
     
  4. Timothy

    Timothy Member

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    Nope.
    The above relates to testing for film fixing, which I was already aware of. The stuff that I saw recently specifically gave a method for testing printing materials (paper) for fixing times.
    Checking that fixer is not exhausted completely, or that a fixed print has been washed thoroughly, ... let's face it, is pretty old stuff for anyone with any amount of experience in a darkroom. Confirming that a given print has received sufficient fixing is also not that hard. But what got my attention in the post that I saw recently was the wholly practical approach to finding the minimum time necessary to achieve just the right amount of fixing, and no more.
    Honest. I am sure that I read it and not dreamed it : )
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Fixer procedure test:

    1. After washing, test for retained silver with the standard test.

    2. After washing test for retained hypo with the standard test.

    PE
     
  6. Rick Jones

    Rick Jones Member

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    David Vestal in his book "The Art of B&W Enlarging" describes the following method for testing the clearing time for papers. Cut a full length test strip 1 X 10. The rest of the test can be done in room light. Use a pencil to mark off 6 or 7 evenly spaced sections. Put the whole strip in your stop bath for 1 full minute with constant agitation. Then dunk the strip, with agitation, one section at a time in your fresh fixer. You choose the time per section but 10 seconds seems about right. After the last section has received its 10 sec dunk get the whole strip to a tray of running water and wash for, say, 2 minutes. Now put the strip in the developer for 5 minutes with agitation. Again, this is all done in room light. After 5 min move the strip to your stop for 30 sec, rinse and examine under a good light. If the whole strip is white, all the fixing times were too long. If the whole strip is dark or stained, all fixing times were too short. If your strip includes the paper's clearing time you will have some black or stained sections and at least one paper white. The time that section spent in your fix is the clearing time for your paper in fresh fix. Multiply that time by 2 and you have your optimum fix time. Photographer's Formulary offers a residual silver test solution which can accomplish the same thing but I like the simplicity of the Vestal method. Tim Rudman's "Master Printing Course" offers a variation of David's method on page 136. Tim, while I'm not sure were you read about the test I'll bet it was very similar to what I have described.
     
  7. dancqu

    dancqu Member

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    Well there may be a "...practical approach to finding
    the minimum time...". But in the usual use of fixer that
    minimum time would apply only to one specific print.
    In short, knowing a minimum time has no value. At
    least for those who use fixer in the usual way.

    For myself knowing the minimum time IS of value
    because I use fixer very dilute one-shot, ie the
    fixer is good for A or A few at the same time
    prints. Dan
     
  8. 2F/2F

    2F/2F Member

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    Wow. You're blowin' my mind here! :wink:

    Anywhere where "the standard test" is described?
     
  9. Ray Heath

    Ray Heath Member

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    g'day Tim

    does fixing need to be so precise?

    always fix for at least the minimum time prescribed for that fixer, a little longer does no harm, but never grossly longer
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    Lots of places even here on APUG.

    There are several photo companies that sell test kits as well as the old Kodak test kits. They also published the formulas for both of the test kits. This is an exercise left to the student. :D

    PE