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  1. #11
    Photo Engineer's Avatar
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    Erik;

    I have no idea. I have to say, based on few experiments, that I doubt that what you wish to do is possible.

    PE

  2. #12
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    Quote Originally Posted by Erik L View Post
    ...but doesn't seem to have many practitioners in the alt photo world - there must be a reason...
    I wouldn't be so certain, yet. Just because no one uses CMC gum as a substrate is not necessarily because it won't work, but because hardly anyone does original experimentation. You know of it because you're a potter, but I'd bet that most alt processors don't know what it is (I certainly didn't before PE mentioned it to me privately).

    The only way to be sure is to try it yourself and evaluate the results.

    I'd encourage further exploration.

  3. #13
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    I came upon this old post and did a little more searching, had some results to share.

    From this PDF (p.24) for AQUALON®.

    The effect of trivalent cations on CMC solutions can be controlled and used to advantage where gelation is desired. Gels of varying texture can be produced by careful addition of certain salts of trivalent metals, such as aluminum. Gradual release of aluminum ions to a CMC solution will result in uniform crosslinking of the polymer molecules between carboxymethyl groups. Gradual release of aluminum ions can be accomplished by using a slowly soluble aluminum salt such as monobasic aluminum acetate, AlOH (C2H3O2)2; soluble salts such as aluminum sulfate, Al2 (SO4)3, in combination with appropriate chelating agents; or insoluble salts such as dihydroxyaluminum sodium carbonate (DASC), Al(OH)2OCOONa, followed by in situ formation of the soluble acid form of DASC.

    Properties of CMC gels depend on many factors. In general, the stiffness of a CMC gel increases with:

    - An increase in CMC concentration
    - An increase in CMC molecular weight
    - An increase in the concentration of trivalent metal ion.
    - A decrease in solution pH.

    Techniques for producing CMC gels by crosslinking with trivalent metals are discussed in more detail in Aqualon Bulletin VC-521 and Bulletin VC-522.


    I tried looking for these bulletins, to no avail. But at any rate, there appear to be methods for crosslinking / hardening CMC gums. The nice thing about this gum is that it's easy to work with and doesn't cold set like gelatin; so in some sense it might be more convenient to work with. Who knows though.. just putting info in the right places in hopes that someday it'll be useful to someone.

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