Calling all chemistry geeks: how to test your washing effectiveness

Discussion in 'Darkroom Developing and Printing' started by David Nebenzahl, Nov 25, 2003.

  1. I may have made fun of you guys in the past, with your fascination with
    decahydrates, borates, and your bubbling beakers and test tubes down in your
    medieval laboratory.

    But now I could use your help: is there any way to test the effectiveness of
    one's washing procedure, for both film and paper?

    We test film and developer, and do print tests. Yet I don't know of anyone who
    actually tests their finished prints to make sure that the hypo is actually
    washed out of them.

    Is there any way to test this? Say, some magic chemical that would turn bright
    fluorescent orange in the presence of residual hypo in a print or on film?
    Nah, didn't think so. But if there's any way to do this, it seems that those
    of us who care about this might want to do this test after getting the rest of
    our procedures down.
     
    David Nebenzahl, Nov 25, 2003
    #1
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  2. Sure there is. You can use a residual silver test to test if you fixed
    enough (Kodak ST-1) and you can use a test for residual
    argentothiosulphates to see if you washed enough (Kodak HT-2). If HT-2 is
    not accurate enough for you, you could use ANSI test Z38.8.25-1950 (a
    more recent version may be available) for prints or PH4.8-1971 (here also
    a more recent version may be available) for negatives.
     
    Jean-David Beyer, Nov 25, 2003
    #2
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  3. David Nebenzahl

    Tom Phillips Guest

    And that's why you aren't privy to the patented secrets of gold alchemy
    that have made us all rich enough to sit in front of our computers
    answering questions...

    Like Jean-David said, there is. The formulas have been posted many
    times. Do a rec.photo.darkroom google search for "washing" or maybe
    "hypo test" and they should come up. Also, you can call Kodak
    800-242-2424 ext. 19 and ask them to send you the photo copied versions
    of either Kodak Pub. J-1 Using Black and White Chemicals or Pub. F-40
    Conservation of Photographs. Both have the formulas.
     
    Tom Phillips, Nov 25, 2003
    #3
  4. The other route to go is to change over to Photographers Formulary non
    acidic stop bath and their TF4 fixer... No testing needed... Wash times in
    minutes for a non acidic, archival print...
    Denny
     
    Dennis O'Connor, Nov 25, 2003
    #4
  5. David Nebenzahl

    Mike King Guest

    Yeah. but, he wants to KNOW first hand, not take your word for it or word of
    the wash aid supplier, the paper maker, the company that made the chemicals
    he uses or the bloke that made his print washer.

    David Vestal's books (The Art of Black and White Enlarging and The Craft of
    Photography) have the formula, the procedure he used to test (slightly
    different in the two books but either will work) and the results (by all
    means repeat his tests for your washer+your paper+your chemical choices+your
    local water supply, etc.).
     
    Mike King, Nov 25, 2003
    #5
  6. Thanks for that information. I just got off the phone with the large yellow
    company, who very nicely agreed to send me a copy of publication J-1. (F-40
    turns out to be a larger book which you have to pay for.)
     
    David Nebenzahl, Nov 25, 2003
    #6
  7. David Nebenzahl

    Tom Phillips Guest

    no, Kodak provides an excerpt called "Processing for black and white
    stability" they photocopy and send out for free. Call them back. It's
    excerpted from Pub. F-40 and consists of chapter 6 from Conservation of
    Photographs and includes an excerpt from Pub. J-1 on formulas for
    testing stop/fixer baths and film/print hypo tests.
     
    Tom Phillips, Nov 25, 2003
    #7
  8. Ummm, OK Mike - I stand duly chastised that your opinion is definitive...
    Unfortunately, TF4 doesn't contain 'hypo' so he can use the thiosulfate test
    kit on a print fresh out of the fixer and still get a zero... I guess that
    will make him feel better, eh? Waste of money though, pity that...

    Denny

    of
     
    Dennis O'Connor, Nov 26, 2003
    #8
  9. TF-4 DOES contain "hypo", its just ammonium thiosulfate
    rather than sodium thiosulfate. All "rapid" fixers contain
    ammonium thiosulfate.
    The silver nitrate test works for both.
     
    Richard Knoppow, Nov 27, 2003
    #9
  10. Residual hypo can be tested for using the Kodak Silver
    Nitrate test.
    HT-2 Test Solution
    Water 750.0 ml
    Acetic Acid, 28% 125.0 ml
    Silver Nitrate, crystals 7.5 grams
    Water to make 1.0 liter

    This is a lifetime supply unless you want to do total
    immersion testing.
    For normal testing place a drop or two of the test
    solution on a clear area of the print or negative. Allow to
    stand for about two minutes, then blot off.
    Residual hypo will react with the acidified silver nitrate
    to form brown Silver sulfide. There should be no more than a
    very slight stain after blotting off the test solution.
    A more elaborate version of this test is available for
    quantitive measurement using a densitometer but the above
    will give a reasonable estimate of the effectiveness of
    washing.
    This, and other test formulas, can be found in the Kodak
    publication _The Kodak Black-and-White Darkroom Dataguide_
    which is available from photo dealers with darkroom
    departments or from Kodak.
     
    Richard Knoppow, Nov 27, 2003
    #10
  11. David Nebenzahl

    Tony Wingo Guest

    No. It's an ammonium thiosulfate based fixer, basically a proprietary
    version of TF-3, so residual thiosulfate tests should work just fine.

    -t
     
    Tony Wingo, Nov 27, 2003
    #11
  12. I'll run a residual test and see if it reacts...
    Denny
     
    Dennis O'Connor, Nov 27, 2003
    #12
  13. David Nebenzahl

    Jan T Guest

    I'd prefer the solution of Amaloco: test solution goes in 2 little glass
    containers, and in the first you let drip off some of the water from the
    washed print. Then compare both solutions, they should be visually equal.
    This way one does not need to contaminate the print; if the washing test
    with Kodak HT-2 turns out positive, you have a nasty stain on your print. If
    the drip-off test turns out positive, one can continue washing and repeat
    the test without damage.

    www.amaloco.nl - not very informative but it's there.

    Jan
     
    Jan T, Nov 27, 2003
    #13
  14. Not informative at all for me, unfortunately: text in Dutch, German and
    French, but not English. Time to learn another language?
     
    David Nebenzahl, Nov 27, 2003
    #14
  15. Well, I know French, but they just sell a developer that uses neither
    hydroquinone nor sodium hydroxide. Who cares?
     
    Jean-David Beyer, Nov 28, 2003
    #15
  16. This is a very old test using Potassium Permanganate. It
    is not effective because it does not measure the amount of
    residual hypo in the emulsion or paper support, only in the
    water coming off the print. Because hypo can be bound to
    both gelatin and paper fibers the test fails especially were
    there is a fairly low concentration of hypo in the material.
    The best method of testing is to process a scrap print
    with the run of prints. That way it can be tested without
    damaging anything. Film is not so much a problem because
    there is often enough clear margin to make a test without
    damaging the image if it fails.
    The permanganate test has not been in general use for
    about fifty years.
     
    Richard Knoppow, Nov 28, 2003
    #16
  17. I don't see anything else either.
    However, from the description this is probably like Kodak
    HT-1a.

    Kodak HT-1a Residual Hypo Test Solution- Stock

    Distilled water 180.0 ml
    Potassium Permanganate 0.3 gram
    Sodium Hydroxide 0.6 gram
    Distilled water to make 250.0 ml

    The solution is used by diluting it with distilled water 1
    ml of test solution to 125 ml of water for film, 1 ml of
    test solution to 250ml of water for paper. Water from a
    precribed number of prints is allowed to drain into the
    solution. IF there is excessive hypo _in the water_ the
    solution will turn orange and then clear. Oxidizable organic
    matter in the water will cause the test to fail. It should
    be tested with a sample of the water used for washing before
    testing for hypo.
    I am not giving further details since the Silver Nitrate
    test is much more effective and the above has not been
    recomended since the 1940's.
     
    Richard Knoppow, Nov 28, 2003
    #17
  18. David Nebenzahl

    Dan Quinn Guest

    That would be the potassium permanganate test. It, KMnO4,
    will oxidize anything in the wash water which can be oxidized,
    including thiosulfate. In doing so it changes color.
    I wonder, are amaloco's instructions complete? Do they include
    a test for the water itself?
    I've placed an order with Photographer's Formulary which includes
    10 grams of KMnO4. I'll be using that and the HT-2 test in my off
    and soon on again hypo and washing tests. Dan
     
    Dan Quinn, Nov 28, 2003
    #18
  19. KMnO4 is also available at pet & pond stores as a fish medicine, is
    used for water purification and is available in most pharmacies though
    you may need an Rx.
     
    Nicholas O. Lindan, Nov 29, 2003
    #19
  20. I tried the "LMnO4" test years ago, and still have most of the crystals
    left. The test is just too insensitive to be useful. If it fails the
    test, you can be pretty sure you have not washed enough, but if it
    passes the test, you know nothing.
     
    Jean-David Beyer, Nov 29, 2003
    #20
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