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Thread: Is Chrome Alum and Potassium Alum The Same?

  1. #1

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    Is Chrome Alum and Potassium Alum The Same?

    I have a formula that calls for Chrome Alum as a hardener.

    I have some Potassium Alum on hand and I wanted to check if these two chemicals are effectively used for the same purpose?

    Thanks in advance.

    Larry

  2. #2
    Vaughn's Avatar
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    Re: Is Chrome Alum and Potassium Alum The Same?

    I believe the Potassium Alum (potassium aluminum sulfate) will act slower than the Chrome Alum (Chromium(III) potassium sulfate).

    I have only used it on its own (not in a formula) as a gelatin hardener and help clear carbon prints.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  3. #3
    Tin Can's Avatar
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    Re: Is Chrome Alum and Potassium Alum The Same?

    One more question

    Is Food Grade ALUM as bought in US stores, usable as hardener?

    I tried it once with J Lane Plates, but couldn't tell and stopped.
    sin eater

  4. #4
    Nodda Duma's Avatar
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    Re: Is Chrome Alum and Potassium Alum The Same?

    Chrome Alum and Potassium Alum are not the same.

    While they both harden, chrome alum works faster and also aids adhesion to glass.
    Newly made large format dry plates available! Look:
    https://www.pictoriographica.com

  5. #5

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    Re: Is Chrome Alum and Potassium Alum The Same?

    Thanks for confirming. It seems that Chrome Alum is a little hard to come by at this time...

    Anyone know of a source in the USA that has some in stock?


    Quote Originally Posted by Nodda Duma View Post
    Chrome Alum and Potassium Alum are not the same.

    While they both harden, chrome alum works faster and also aids adhesion to glass.

  6. #6
    Vaughn's Avatar
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    Re: Is Chrome Alum and Potassium Alum The Same?

    Quote Originally Posted by Tin Can View Post
    One more question

    Is Food Grade ALUM as bought in US stores, usable as hardener?
    I quickly checked via google -- mixed answers...seems to be confusion as to what Alum is!
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  7. #7

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    Re: Is Chrome Alum and Potassium Alum The Same?

    Food grade will be generally potassium alum or otherwise sodium alum. Both should act as a hardener, but you'll need more of it than chrome alum to reach the same degree of hardening, or hardening time needs to be extended. A friend of mine used food grade alum for making hypo alum toner, which worked fine. Different qpplication of course!

  8. #8

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    Re: Is Chrome Alum and Potassium Alum The Same?

    Sigma Aldrich carries it. This is th 98% grade https://www.sigmaaldrich.com/catalog...g=en&region=US

  9. #9
    Tin Can's Avatar
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    Re: Is Chrome Alum and Potassium Alum The Same?

    Thanks for the responses

    Food Grade is found in the baking section at my local Kroger

    Online they add it is Kosher and good for dying fabrics!

    $1.99 can 2.37 oz UPC: 0001111000309

    As a child I was given chunks of Alum for mouth cold cores, yet haven't that problem since
    sin eater

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