I am curious to know... (Residual hypo & silver tests)

Discussion in 'B&W: Film, Paper, Chemistry' started by Digidurst, Aug 1, 2005.

  1. Digidurst

    Digidurst Subscriber

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    if any of you use either of these two tests (or both, perhaps)?

    Residual hypo test

    or

    Residual silver test

    I want to make sure I'm "doing things right" so was thinking about trying one of these products but I would appreciate your input on the matter. If you don't use chemical testing, how are you sure you've washed long enough? Thanks!
     
  2. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I think both are unnecessary to determine the answer the question you are asking: Is my print CLEAN?

    Two or three drops of a toner (selenium working strength) on a wet, but blotted white border, left for two or three minutes will indicate if there is any silver left in the print. The area will turn yellow if silver remains after fix and hypo.
     
  3. Claire Senft

    Claire Senft Member

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    I use both.
     
  4. dancqu

    dancqu Member

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    Or, how are you sure the print completely fixed? the test
    for silver. I call that the sulfur for silver test and the other
    the silver for sulfur test. Both tests will produce a
    silver sulfide stain.

    For the BOTH be sure the print has gone through the full
    processes routine. It is possible for all the hypo to be washed
    out and still have silver in the emulsion. To test your technique
    you may wish to do a redevelop. Expose a portion of the
    processed print then redevelop.

    Keep in mind that the hypo is there to carry out the unexposed
    silver. You know the old darkroom saying: "Where there is hypo
    there may be silver."

    The test for sulfur, hypo, has limited life span. That test is
    made up of silver nitrate and acitic acid. At one drop per test
    it is almost certain you'll use only a little of the bottle. I don't
    know why it goes bad. Same goes for the test for silver; a
    very dilute sodium sulfide solution. Off hand I'd say one
    gram of that sulfide would last you a few years;
    just one drop.

    A good thing P. Formulary does sell SMALL quantities. Dan