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  1. #1

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    kodak sb-8 citric acid stop bath

    I want to make this stop bath for prints but need to know which citric acid I need to buy at the health food store...anyone have an idea; please!!
    thanx, Peter

  2. #2
    Photo Engineer's Avatar
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    Peter, Kosher sour salt will do just fine, but you may need to adjust the pH a tad either way with acid or base.

    PE

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    naeroscatu's Avatar
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    Here in Canada I bought citric acid from the bulk store (Bulk Barn - not sure if you have that in USA) and it works well. Many retail food stores have bulk sections, just ask for citric acid.
    Mihai Costea

    "There's more to the picture
    Than meets the eye." - Neil Young

    Galleries:My PN & My APUG

  4. #4

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    stop bath

    kosher sour salt...never heard of it;only kosher salt....is all citric acid the same?? I have a bunch in Ct. but I'm not there imo....
    Best, Peter

  5. #5
    Photo Engineer's Avatar
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    Sour salt is citric acid. Kosher salt is not. Almost all Sour Salt on the shelves here is Kosher.

    Citric acid can be associated with up to 3 counter ions which can render it increasingly less and less acidic. The pure acid is quite acidic, but addition of sodium ions render it more and more alkaline as the acid forms the sodium salts. Usually in a stop bath you buffer it with sodium citrate at a pH from 4.5 to 6.5 by the addition of alkali such as sodium carbonate or sodium hydroxide until it reaches the desired pH.

    PE

  6. #6
    Matthew Gorringe's Avatar
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    And I thought I could just use a 2% solution....

    Is pharmaceutical grade citric acid likely to need buffering and where do the sodium salts come from, tap water?
    Matt Gorringe

  7. #7

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    Ilford Ilfostop

    Quote Originally Posted by Peter Schrager View Post
    I want to make this stop bath for prints but need to know which citric acid I need to buy at the health food store...anyone have an idea; please!!
    thanx, Peter
    Hi Peter:

    Perhaps you can simply used Ilfostop, as itis citric acid based:

    http://www.ilfordphoto.com/products/...ndry+Chemicals

    I assume you want to try this because it doesn't smell. Ilfostop is virtually odourfree. I can only smell it if put my nose about an inch away, and it is not that bad smelling...

    Tom

  8. #8
    Photo Engineer's Avatar
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    For all practical purposes, Citric Acid can be used alone.

    PE

  9. #9

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    I use 1 tablespoon of citric acid per liter of water when printing and it seems to work just fine. I get it from The Chemistry Store: http://www.chemistrystore.com/Chemic...tric_Acid.html

    Richard Wasserman

  10. #10

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    Quote Originally Posted by Photo Engineer View Post
    Sour salt is citric acid. Kosher salt is not. Almost all Sour Salt on the shelves here is Kosher.

    Citric acid can be associated with up to 3 counter ions which can render it increasingly less and less acidic. The pure acid is quite acidic, but addition of sodium ions render it more and more alkaline as the acid forms the sodium salts. Usually in a stop bath you buffer it with sodium citrate at a pH from 4.5 to 6.5 by the addition of alkali such as sodium carbonate or sodium hydroxide until it reaches the desired pH.

    PE
    Is there any practical value to buffering? Perhaps it increases the capacity? SB-8 exhausts rather quickly IIRC.

    The SB-8 formula is 15 grams of Citric Acid and water to make 1 liter. How much sodium carbonate (which I've got) would you suggest as a buffering agent? I don't own a pH meter.

    Thank you.

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