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  1. #1
    JRieke's Avatar
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    mixing half kodak D-76

    This may be a stupid question but I'm new to this and haven't been able to get an answer anywhere.

    I picked up a package of Kodak D-76 developer recently. The instructions say to mix it in a full one gallon jug. However, since I doubt that I will use a full gallon before it goes bad, would it be acceptable to mix only half the packet?

    What would be the best way to store the leftovers? What is the best way to measure half the powder out? I have a postage scale but I don't know if that is accurate enough to give good results.

    Any feedback is appreciated.

    Thanks

    Jeremiah

  2. #2
    Photo Engineer's Avatar
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    Jeremiah;

    There is probably a thread every month on this very subject.

    Do not ever mix part of a powder chemical kit. They just are not uniform enough.

    PE

  3. #3

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    This has been discussed most recently here about XTOL, if I recall correctly. Anyway, my take on the idea is that it is not a good one for a couple of reasons. First, there is no way to guarantee that you'll get an even distribution of all the components that go into that package of D-76. Measuring out exactly equal portions does not guarantee that you'll have just the right amount of each ingredient in each portion. Second, the dry ingredients are packaged in a hermetically sealed envelope containing an inert gas. Once opened, the contents are exposed to oxygen and moisture and will oxidize. Net result, you save nothing because you'll wind up with a batch of bad chemistry that won't work as expected.

    Sorry to bust your idea, but that's the story. The best way to keep D-76 is to mix up the entire volume and then split it up into smaller bottles, each full to the brim. This way the only bottle with an airspace is the one you're working. The completely full ones will last at least 6 months. The partially full ones, at least a month.

    I prefer PET or PETE plastic bottles, the kind in which soda pop and bottled water are sold. Glass is arguably the best; but it is expensive, fragile, and potentially dangerous. I have experienced no problems using the PET and PETE bottles. Other types of plastics are not suitable because they are too gas permeable for long term storage.
    Frank Schifano

  4. #4
    JRieke's Avatar
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    That was what I needed to know. Thanks for the response! I'll go get a couple half gallon jugs.

  5. #5

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    Actually, I recommend even smaller bottles. 1L or even 1/2L bottles are even better.
    Frank Schifano

  6. #6
    JRieke's Avatar
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    are used soda bottles acceptable then?

  7. #7

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    Yes, they work just fine. PETE plastic isn't very gas permeable, which is why it is used for carbonated drinks, and usually can withstand 75psi of pressure.
    Tho the pressure resistance isn't really needed for storing D76 for half a year or so. I also use them for RA-4 colour chemistry as well, and a part full bottle of developer easily lasts two months as you can squeeze all of the air out.

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    Thats realy cool idea,think Snapple ice tea is a pete plastic Bob?.

  9. #9

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    Sorry to hijack, (sorta) but what are the Jobo 1 litre bottles made of, and are they any good for a few months or so of storage?

    Bob H
    "Why is there always a better way?"

  10. #10
    Martin Aislabie's Avatar
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    Quote Originally Posted by BobNewYork View Post
    Sorry to hijack, (sorta) but what are the Jobo 1 litre bottles made of, and are they any good for a few months or so of storage?

    Bob H
    Jobo translucent bottles are made from HDPE

    They will slowly taint with developer and eventually slowly turn a old developer brown in colour (or at least mine have)

    However all these things are relative, the amount of gassing and permeability of the plastic bottles is insignificant compared to the amount of oxidation a developer gets when it is poured into a bottle.

    To reduce the oxidation of the developer as the storage bottle is filled, I pre-fill the bottles with Tetenal Protectan gas - so any splashing/churning/bubbling as the developer is poured/decanted is done in a developer inert atmosphere rather than an oxygen rich one.

    I am not sure the Protectan is available on your side of the pond - but there is probably a suitable alternative

    Protectan - http://www.tetenal.com/index_c.htm?A...000500055&L=UK

    Martin

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