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  1. #1
    David Lyga's Avatar
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    need advice with cloudy mixture

    When I mix Dektol I get a nice, clear solution (Philadelphia tap water).

    But when I mix D-72 I get a milky, cloudy solution after I add the sodium carbonate. Why, and what can be done to rectify this? The D-72 works fine but I store my solutions in clear PET plastic bottles and I hate to see the cloudy solution on my shelf (there really ARE worse things to complain about, true).

    Philadelphia tap water is not hard: it makes a nice lather with soap. What does the proprietary formula (Dektol) have to prevent this? - David Lyga

  2. #2

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    I assume the commercial product includes some additional compounds (like a sequestering agent) so that it is as flexible as possible depending on water qualities. That is usually the difference between packaged developers and the published formulas when they are known to be the same (although in the case of D72 I have never been sure if it is truly the same developer as Dektol).

    Presumably a better test would be to mix both using distilled/demineralized water.

  3. #3
    David Lyga's Avatar
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    No Dektol is said (by Kodak) to actually have somewhat INCREASED capacity. There is a slight difference. But what MAKES the cloudiness? That is what I want to nail. There are people who have a foundation in chemistry that would be able to respond fully. Thank you Michael R.

    I just did a Google search and, indeed, Philadelphia water is moderately hard. This problem might be a precipitation of calcium carbonate that is causing the cloudiness. Any further advice appreciated. - David Lyga
    Last edited by David Lyga; 05-11-2012 at 08:56 AM. Click to view previous post history.

  4. #4

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    A couple of years ago I went back to Dektol and also get a clear solution. I have never tried D-72. Why not try mixing it with distilled water and storing in a glass container to see if there is a difference? My house is on well water that is treated with a home system and although soap lathers just fine I don't know what the chemical contents are. Our second well for the pool and sprinkler system doesn't go through the other system and contains enough iron and probably calcium carbonate to be noticeable. I suppose that despite the difference in my two systems the undesirable properties are still present but greatly reduced. We have no chlorine added which could be a factor in your municipal system. The way they treat the water could vary at different times of the year.

    We drink bottled water just in case.

    http://www.jeffreyglasser.com/

  5. #5
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    When I mix D-72, it gets slightly cloudy right after I add the sodium carbonate. I think this is because the carbonate contains a small amount of insoluble material. I use Ph-plus, a swimming pool chemical that is sodium carbonate but probably also contains a small amount of impurities. After the solution sits a few hours, it gets a lot more cloudy. This may be from some reaction between some of the ingredients or between some of the ingredients and impurities in the well water or other ingredients. After a couple of days the suspended insoluble material settles to the bottom of the container as a thin layer of precipitate, and the solution is clear. The clear solution seems to work as it should.

    But I seldom mix D-72 this way. Usually I mix it from dry chems at tray dilution and use it right away even though slightly cloudy, and it seems to work as it should.
    Happiness is a load of bulk chemicals, a handful of recipes, a brick of film and a box of paper. - desertrat

  6. #6

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    The cloudiness is due to calcium ion being precipitated as calcium carbonate. There are two ways of preventing this. You can boil the tap water and allow any precipitate to settle overnight and then decant the clear water for use in developers. This removes the temporary water hardness. 5 to 10 min of boiling should do it. The other method is to use a chelating agent. Calgon (Kodak Anticalcium #1 or sodium hexametaphosphate) is a cheap and effective sequestering agent. Use 2 to 5 grams per liter of D-72 depending on the hardness of your water.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  7. #7
    Nicholas Lindan's Avatar
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    Along with S. Hexametaphosphate you can use EDTA.

    Don't use the Calgon found in the laundry aisle. It used to be SHMP but isn't any longer, although SHMP is still refered to as "Calgon". Laundry Calgon is something else now, and it stinks to high heaven with the usual gag-me-with-a-spoon laundry scent [designed to keep men out of the laundry room, near as I can figure]. Soap is chemically related to Estrogen, Cholesterol to Testosterone - makes sense to me.

    When making up stock, adding a teaspoon / gallon of either SHMP or EDTA will take care of the problem.

    --

    Looked up the MSDS for the current incarnation of Calgon:

    Carbonic Acid
    Sodium Citrate
    Sodium Sulfate
    Last edited by Nicholas Lindan; 05-11-2012 at 11:51 AM. Click to view previous post history.
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  8. #8

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    Quote Originally Posted by Nicholas Lindan View Post
    ... and it stinks to high heaven with the usual gag-me-with-a-spoon laundry scent [designed to keep men out of the laundry room, near as I can figure]. Soap is chemically related to Estrogen, Cholesterol to Testosterone - makes sense to me.
    Nicholas,

    This is the funniest thing I've read in weeks. Thanks.

    David,

    You are getting calcium carbonate cloudiness. Using distilled or demin water should solve your problem.

    Best,

    Doremus

    www.DoremusScudder.com

  9. #9
    David Lyga's Avatar
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    Thank you all: I will try what you have recommended. But, Gerald Koch, I have already tried adding Kodak Anti-Cal to no effect. I will try boiling the water.
    I, stupidly perhaps, would have no idea how to get ahold of either EDTA or SHMP. - David Lyga

  10. #10

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    Beside Calgon the following chemicals can be used to sequester calccium. Sodium tripolyphosphate and sodium tetraphosphate. Some sequestering agents are available from www.chemistrystore.com. They are quite reasonable and this company also sells several chemicals of interesst to photographers. These chemicals belong to a class of compounds called condensed polyphosphates.
    Last edited by Gerald C Koch; 05-11-2012 at 05:21 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

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