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  1. #1
    AndreasT's Avatar
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    Potassium Bromide gone solid need opinion please

    I have some Potassium Bromide from a friend and it has backed together. Now I would like to use it for developers. As far as I know it last indefinitely. What I am concerned about is how to measure it for recipes. Should I leave the bottle open and measure it as monohydrate after awhile. Or put it in my oven and dry it out and use it as anhydrous.
    Or discard of it.
    In recipes they always talk about anhydrous and monohydrate sodium carbonate but not with other chemicals much.

  2. #2
    Athiril's Avatar
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    It has a high melting point (relatively speaking to your oven), so I would dry it out.

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    Bill Burk's Avatar
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    I keep hearing advice to make a 10% solution and measure from that. Seems you could do that by weight.

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    I've a bottle of PB since forever, at least 20 years.

    I suggest that you just put it in an oven or toaster oven at the very lowest heat and let it dehydrate. The physical nature may not change much, you may need to smash the heck out of it, or do mortar and pestle, but the chemical will not change.

    Since PB is just a restrainer, it's not like you can really mess things up.

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    Potassium bromide does not form any hydrates. My suggestion would be to chip some out for weighing to make a 10& solution. If necessary some larger pieces could be ground up in a mortar.
    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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    Hello,
    put it into a clean plastic bag, lay it on the floor and pulverize it with a hammer. Or use a porcelain mortar from laboratory equipment.

  7. #7
    Mike Wilde's Avatar
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    I have a small mortar and pestle that normally lives on top of my jar of KBr, dedicated to breaking it up. About $6 from a specialty cooking store.

    I expect to find it gone to a rock like state.
    my real name, imagine that.

  8. #8
    AndreasT's Avatar
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    Thanks for the answers. It helps.

  9. #9
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    I bought a huge bottle of Potassium Bromide in the '50s. It is still good.

    The nature of the halide salts is to clump! They all do. Table salt clumps. They put an additive in it to prevent clumping and that is why table salt should not be used when you need Sodium Chloride in a photographic formula.

    PE

  10. #10
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    Quote Originally Posted by Photo Engineer View Post
    I bought a huge bottle of Potassium Bromide in the '50s. It is still good.

    The nature of the halide salts is to clump! They all do. Table salt clumps. They put an additive in it to prevent clumping and that is why table salt should not be used when you need Sodium Chloride in a photographic formula.

    PE
    Sorry to go off thread a little here, but how does the non-clumping additive effect Sodium Chloride in a photographic formula? The reason I ask, is that I have never noticed a problem with this.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

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