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Thread: Washing Soda?

  1. #21
    gainer's Avatar
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    Of course it will tend toward the monohydrate in an open container. One still pays for shipping the water of crystallization.

    A saturated solution doesn't need math to prepare, but its saturation point will vary with temperature. You can simply keep adding washing soda or whatever crystalline form it happens to be until some remains at the bottom of the container and keep the solution at constant temperature. If it it saturated at one temperature, it will be at lower temperatures provided it didn't supercool. There are tables that can tell you the concentration of a carbonate solution by the weight of 100 ml of it. Most of our uses of carbonate do not require great accuracy of measurement
    Gadget Gainer

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    Will run these tests tomorrow

    Carefully scraped off level tablespoon of each:

    1. SC anydrous, screw top container that lived most of its life in Dever, i.e., dry. Closed, of course. Opened maybe three times briefly here in humid Florida.

    2. Super Washing Soda, opened and in a closet here for years. Not so many that the silverfish have yet to find the pasteboard.

    3. Super Washing Soda purchased yesterday. Who knows where it's been?

    My scale is an Ohaus Centigram, hundredth of a gram.

  3. #23
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    re the red devil shortage

    I use sodium hydroxide in some of the lith developers I mix. I also use a whole lot more in a soap making venture/holbby that I uses to underwrite this disease we call GAS.

    I too started with Red Devil, but found that often I had to ask my hardware store to order it in. Then I found a place to sell it to me bulk. For the price of 17 red devil cans I came home with 25kg of sodium hydrixide granules - that works out to 93 red devil cans worth.

    There was, of couse, the nagging feeling that someone from law enforcement would be knocking on the door in a day or two after I bought that. It never happened though. I would like to see how they would react to all of the photo chemistry that I have on the shelves, though.

  4. #24

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    [QUOTE= I would like to see how they would react to all of the photo chemistry that I have on the shelves, though.[/QUOTE]


    "Sir, you have the right to remain silent..."

  5. #25

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    Quote Originally Posted by Paul Verizzo View Post
    Carefully scraped off level tablespoon of each:

    1. SC anydrous, screw top container that lived most of its life in Dever, i.e., dry. Closed, of course. Opened maybe three times briefly here in humid Florida.

    2. Super Washing Soda, opened and in a closet here for years. Not so many that the silverfish have yet to find the pasteboard.

    3. Super Washing Soda purchased yesterday. Who knows where it's been?

    My scale is an Ohaus Centigram, hundredth of a gram.
    OK, the envelope please....

    Per one level tablespoon,

    Anhydrous, 15.77 grams

    Old Washing Soda, 17.44

    New Washing Soda, 17.83

    Using 17.5 as a general weight for the washing sodas, that would mean one would need 10-11% more than for anhydrous.

    In any recipe I've ever seen for soda, there is so much latitude as to be very forgiving. IIRC, I've put 5 grams of anyhydrous in a liter of water for a pH 10.5. Up that to 90, and you can get it to 11. Twenty time the carbonate to get five times the alkalinity. The latter, of course, does have much greater reserves of pH.

  6. #26
    Ole
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    Paul, are those the weights after dehydration? If so, what were the weights before dehydration?
    -- Ole Tjugen, Luddite Elitist
    Norway

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    Quote Originally Posted by Ole View Post
    Paul, are those the weights after dehydration? If so, what were the weights before dehydration?
    As is.

  8. #28
    Ole
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    So what you have is the weight of one teaspoon sodium carbonate of unknown hydration? That's going to vary with the size and shape of the grains, and can't really be used to determine anything, I'm afraid. Could be useful if you just want a quick way to measure out an approximate weight of chemical, but not for determining how much you need of one to replace another one...
    -- Ole Tjugen, Luddite Elitist
    Norway

  9. #29

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    Quote Originally Posted by Ole View Post
    So what you have is the weight of one teaspoon sodium carbonate of unknown hydration? That's going to vary with the size and shape of the grains, and can't really be used to determine anything, I'm afraid. Could be useful if you just want a quick way to measure out an approximate weight of chemical, but not for determining how much you need of one to replace another one...
    No.

    All this little experiment was, was a followup to PG's comments on the hydration levels of the washing soda vs. anhydrous. In no way an attempt to make a tablespoon equivalent, although there's no reason why not.

    All the products look exactly the same. So, if a recipe calls for 40 grams of SC anhydrous, just use 44 grams of washing soda. You'll be close enough for any use that I'm familiar with.

    Of course, you could heat the soda and get anhydrous, too.

  10. #30
    Ole
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    46.8g monohydrate, I make it - not 44.

    Or 107.9g dekahydrate, if that's what you have.

    weighing before and after dehydration seems to be the best way to find out what you have, especially as a commercial product may be a mixture of anhydrous and monohydrate, or mono- and dekahydrate.
    -- Ole Tjugen, Luddite Elitist
    Norway

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