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Thread: Expired Hypo Clear

  1. #1

    Join Date
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    Expired Hypo Clear

    My jug has a notation I wrote "discard 1 June 2013"
    Do you think it is still worth using? I'm all set up to print tonight and I'd hate to postpone it until I can get some more so I'll have to wash the fiber base prints longer....or go back and hypo clear the prints in day or two when I get more chemical.
    What say you wise photographers?
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  2. #2

    Join Date
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    Re: Expired Hypo Clear

    I'd use it. I might run it through a fine strainer first.
    You can't depend on your eyes when your imagination is out of focus. ~ Mark Twain

  3. #3

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    Re: Expired Hypo Clear

    HCA is a mixture of sodium sulfite and sodium bisulfite, IIRC. It shouldn't really 'expire'.

  4. #4

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    Re: Expired Hypo Clear

    Quote Originally Posted by Mark Sampson View Post
    HCA is a mixture of sodium sulfite and sodium bisulfite, IIRC. It shouldn't really 'expire'.
    The practical issue I've had is a precipitate, white crunchies, forming in the concentrate bottle during storage.
    You can't depend on your eyes when your imagination is out of focus. ~ Mark Twain

  5. #5

    Join Date
    Feb 2013
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    Re: Expired Hypo Clear

    It becomes exhausted. It doesn't expired. You should always keep some hypo test around. It's so simple.

  6. #6

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    Re: Expired Hypo Clear

    Thanks guys! There are no crunchies, so maybe it's ok. Then again, I can pick up and mix some fresh stuff today.
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  7. #7
    Robert Hall's Avatar
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    Re: Expired Hypo Clear

    HCA working solution turns from sodium sulfite to sodium sulfate in about 4 hours in a tray. It oxidizes very quickly. Sodium sulfate has little effect of removing fix from prints or film.

    From our friend Richard Knoppow...

    The problem with sulfite is that it becomes sulfate when
    it absorbs oxygen. Since one of the main purposes of sulfite
    in developers and fixing baths is to absorb oxygen to
    protect other chemicals it looses its effectiveness with
    time and the protective properties are lost.
    Sulfites also have a specific ion-exchange property for
    thiosulfate. This is one of the main reasons its used as a
    wash aid. Sulfate does no damage but is not as effective as
    a wash aid and AFAIK, does not have the ion-exchange
    property, which actively displaces thiosulfate and
    thiosulfate-silver complexes.
    The rate at which a sulfite solution becomes sulfate
    from exposure to the air depends on its concentration: the
    stronger it is the longer it will last. Of course, the
    amount of exposure is also important, even a strong solution
    will not last more than a few hours in an open tray while it
    will have a life of several months in a closed bottle.
    The soluability of dessicated sulfite is a couple of
    hundred grams per liter (I've forgotten the exact amount) at
    room temperature but its generally not found at
    concentrations much above about 150 grams/per liter in
    practical solutions to prevent crystalization at low
    temperatures.
    In short, sulfate does no harm but is not effective as
    an oxygen absorber or preservative nor as a wash aid.

  8. #8
    http://www.spiritsofsilver.com tgtaylor's Avatar
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    May 2006
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    Re: Expired Hypo Clear

    That's good to know Robert. I mix stock solutions for film 250mm at time and it usually takes about 2 months before having to refill. The stock solution is mixed 10:1 to make a working solution.

    Thomas

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