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  1. #1
    i.candide's Avatar
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    Potassium Bromide

    Hi, I'm going to ask a newbie question...eventually.

    Background: I want to start developing film in caffenol and just took delivery of a Photographer's Formulary bottle of potassium bromide. I expected powder or small crystals - but got large one inch crystals.

    Question: What is the easiest and quickest way to efficiently and effectively get the crystals to a powder or very small crystals? The recipe calls for 1 to 2 grams per litre.

    Can anyone advise using appliances found in a normal household?

    Thanks,
    i.candide
    Dangerous to oneself

  2. #2
    Peltigera's Avatar
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    Pestle and mortar. But be sure to clean it well - KBr is not that good for you.

    Failing that, a coffee grinder - but the crystals might be harder than the grinder is designed to cope with.

  3. #3
    georgegrosu's Avatar
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    I have not seen large crystals of potassium bromide. I saw large crystals (~ 2 cm) of sodium thiosulphate.
    Do 50 ml ~ 20% solution in water and put a piece of not developed film.
    If the film becomes transparent is sodium thiosulfate.
    To test if is potassium bromide you should have a silver nitrate solution.
    George

  4. #4
    MrclSchprs's Avatar
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    Have a look at Caffenol. There you will find at least three different recipes for a coffee based developer. One for slow and medium speed films, one for stand development and one for fast films. The first developer does not need KBr. Check it out, it contains valuable information.

  5. #5

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    One way might be to dissolve the whole lot in water and use it as a stock. Mine is 100g/Litre. It's also handy if you want to add some to paper developer to get warmer tones.

  6. #6

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    Hello,
    put the large crystals in a clean and stable plastic bag, lay it on the floor and take a hammer.

  7. #7

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    Making a 10% solution is the way to go. I make 1l and go through it pretty quickly making bleach and developers.

    Potassium bromide dissolves well in hot (125 f) water.

    Trying to measure out 1 or 2g of the stuff from raw chemistry is a big pain.

  8. #8

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    Does a 10% solution of KBr go bad? That's a dumb question. Better put, how long before it spoils? Thx

  9. #9
    MrclSchprs's Avatar
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    No, it does not go bad.

  10. #10
    Mainecoonmaniac's Avatar
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    Can't you just use large crystals? I have a 20 year old jar with large crystals and I weight it out then dissolve in hot water as needed.
    "Photography, like surfing, is an infinite process, a constantly evolving exploration of life."
    Aaron Chang

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