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  1. #1

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    gum bichromate help..

    I ordered a gum bichromate kit from bostick and sullivan and I am unsure of mixing ratios and such. Does anyone print using B&S gum supplies?
    Does the gum arabic or potassium dichromate need to be mixed with water before mixing them together? If so what is the water to chemical ratio? Any help would be so appreciated!

  2. #2

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    If I were you I would get Christina Anderson's book on alt processes. It has all you ever wanted to know about gum printing. I hear a rumor that she is soon going to publish a book dedicated entirely to gum printing.
    I'm not sure about the B&S kit. They are great folks, but I have no experience with that kit. There should be instructions with it. If there are not, contact B&S.
    The various ingredients are not expensive if you buy them seperately. That's what I would do.
    Good luck,
    Steve
    www.scdowellphoto.com

  3. #3
    sly
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    I ordered the B&S kit last summer. I was surprised when it arrived with no instructions. The links on their website to gum info didn't work either. I emailed 2ce asking for advice, and recieved no answer. I was surprised as I had recieved instructions with pt/pd supplies, and responses to questions when I started with alt prints.
    I have Anderson's book and have figured out, I think, appropriate ratios. The dilutions she uses are not all the same as those provided by B&S. I haven't done any printing yet. I just sized paper tonight and hope to get to printing soon.
    What info, if any do you have so far?

  4. #4

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    More information, maybe?

    Hi, I haven't seen the Bostick and Sullivan kit so not sure what questions I need to answer. If the gum and dichromate arrived as liquids, then they're ready to go as is. If the dichromate arrived as powder, then it needs to be mixed with water, but it depends what dichromate (potassium or ammonium) how much water you'd need to use.

    I'm very surprised there are no instructions. I think for a while they were sending instructions by Stephen Livick (or was that Photographers' Formulary... maybe). Anyway, any instructions would give you a place to start. No two sets of instructions will be the same; the gum process is infinitely flexible and a great range of different combination of ingredients and materials work fine. That's the good news; the bad news is that different gum printers' methods are all very different, and looking at different instructions, or listening to a discussion between gum printers, can be very confusing.

    I'd be happy to answer any specific questions.

    P.S. if you're just looking for a set of basic instructions for gum printing to get you started, here's my outline of how I print gum:

    http://www.pacifier.com/~kthayer/html/method.html
    Katharine
    Last edited by Katharine Thayer; 11-19-2008 at 02:34 PM. Click to view previous post history. Reason: Add P.S.

  5. #5

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    thanks katherine!
    They did arrive in liquid form so that makes things a million times easier. B&S have been really great in helping me, I'm just a little eager to get started. Do you know how flexible gum bichromate is as far as the material that it will print on goes? I am thinking about using foam core, not sure if I should size and/or harden, or if this is even necessary.. or even possible to gum print on.

  6. #6

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    Michelle, I've never tried printing on foam core. Just off the top of my head, I'd say the main problem with it would probably be that the emulsion would tend to soak into the porous material, so yeah, I'd say you should probably size it. There's only one way to know for sure, and that's to try it without size to start, then you'll know if it will print without sizing. But I'd say the probability is pretty high that it wouldn't. That's a challenging material to start with, but it might work really great, and I like the spirit that just dives in; that's the kind of spirit that tends to succeed with gum printing. The people who want to be able to predict every step of the thing before they even start, often get so bogged down in testing this or that aspect that they never get around to making gum prints.

    Gum is pretty flexible so the flexibility of the foamcore shouldn't be a problem. Foamcore isn't any more flexible than paper, is it? You can roll up a gum print on paper without hurting it at all, though it's not something I'd do just routinely. Good luck, let us know how it goes!
    Katharine

  7. #7

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    Your website is amazing. Thank you Katherine

  8. #8
    sly
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    Yes, it's great! Thanks for posting the link!

  9. #9

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    You're very welcome.

    P.S. I just noticed, re-reading the thread Michelle, that your use of the term "flexible" referred back to my earlier use of the term to describe the versatility and adaptability of gum, and on my first quick read I thought you were referring to the physical flexibility of the hardened gum itself. I apologize for misreading, and yes, the flexibility of gum does extend to the material it's printed on; you can print gum on just about anything, though as we discussed sometimes it requires special preparation.
    kt
    Last edited by Katharine Thayer; 11-20-2008 at 08:51 AM. Click to view previous post history. Reason: clarify



 

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