Gum arabic

Discussion in 'Alternative Processes' started by stephen_gray98, Oct 4, 2011.

  1. stephen_gray98

    stephen_gray98 Member

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    I've been using the Photospeed gum dichromate kit and have run out of the 'gum' part and so ordered some 'Roberson & co' Gum arabic. It's thinner than the kit one and I have found that the colour is not clearing so well from the paper and wondered if it is likely to be the gum at issue here ?

    SPG
     
  2. Mike Wilde

    Mike Wilde Member

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    Gum arabic is widely variable. I work my solutions up from a dry powder. It takes a few days to rehydrate, and mixing is a pain.

    I use it only sparingly, occasionally, so I am willing to deal with the hassle.

    Plus, with no preserver, I also use it to put essential oils into an emulsion with a sugar syrup when making up home brew soda flavourings.

    I bought my dry gum arabic supply from an essential oil supplier.


    .
     
  3. pjbtx

    pjbtx Member

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    Hello Stephen:

    Although I do not use the brand of gum you indicate (Roberson), I have seen work from other artists who do use that particular gum. I suspect the gum is fine. You might try different pigments—OR—back off on your exposure a bit—OR—rework the density of your negatives—OR—put a bit of ammonia in the wash to help clear the print.

    If you want a thicker gum solution, try heating the gum over very, very, low heat to evaporate some of the water out from the gum. Hope that helps.

    I do find it a bit unnerving to give advice over the web since I have nothing visual to go by, no before and after shots to examine, and no video giving me an idea of your working technique. So this is just general advice based on 23 years of gum printing. You can see my work and articles at alternativephotography.com.

    Cheers

    Peter J. Blackburn
     
    Last edited by a moderator: Oct 5, 2011
  4. Loris Medici

    Loris Medici Member

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    FWIW, powder gum mixing instructions:
    Prepare 1 parts powdered gum and 2 parts water (all by weight, some use 1 + 3 - it's up to your taste...), pour the water in a large and deep vessel that can be capped, put the preservative (I use sodium benzoate, 1g per 100g of dry gum - I think that's overkill, but doesn't hurt. Others use thymol or similar, don't have a clue about the amount they use...) into the water and mix (if miscible that is; sodium benzoate is - i think thymol is only soluble in alcohol...), pour the gum onto the water, work the gum into the water with a plastic spoon or something, then take a hand mixer and work the mixture for a couple of minutes (it will froth a lot!), cover the vessel to eliminate evaporation and wait overnight, then filter the solution through cheesecloth to its final container. Your gum solution is ready, enjoy! :smile:

    Regards,
    Loris.
     
  5. stephen_gray98

    stephen_gray98 Member

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    Thanks for all the info ! In the end instead of throwing the print out, I ran a foam brush over the print in the water and hey presto the image was clear (after 3 runs). For some reason this gum needs a helping hand to clear whereas the gum in the Fotospeed kit did not. I was suprised that the brush did not remove all the print and seemed to work fine so I hope it works the same on the other layers :pouty: I'm beginning to realise that one small change makes a big difference in the workflow.
    If I run out, I'll try making my own next time as per the instructions above !

    SPG
     
  6. Loris Medici

    Loris Medici Member

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    Good luck! BTW, I actually use a "hand blender" (with the blade "head") not hand mixer! (I'm not too familiar with English terms for kitchenware...)
     
  7. GumPhoto

    GumPhoto Member

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    Loris, I've looked far and wide and I cannot find any powdered gum like that available in Instanbul! Everything else is crap by comparison. so your instructions, I'm afraid, are wasted on those of us in the US. I've gone back to using the cheap black stuff from Daniel Smith. But I really do miss mixing up that good powdered stuff. I've saved an inch-worth just to show people how "good gum" is supposed to look.
     
  8. Mike Wilde

    Mike Wilde Member

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    Try essential oil vendor, and soap making supply outletsas potential vaible sources of gum arabic powder.

    Those folks need a way to get the oils into suspension, rather than left floating on the surface of the final kettle batch.
    This is where the spray dried african and arabian acacia tree gum powder is used.
     
  9. Hexavalent

    Hexavalent Subscriber

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    A pharmacist might have dried gum - it's often used in compounding, sometimes under the name "Acacia".

    You can concentrate liquid gum, by precipitating it with methanol, draining off the water and re-dissolving. This process also 'cleans' the gum somewhat. I've used this technique to turn low quality litho/plate gum into something quite usable.
     
  10. Loris Medici

    Loris Medici Member

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    Really? I feel sorry for you then... (It's tough not being able to source the materials one likes - I always feel put aside when it comes to paper for instance; I don't have any local source for any paper that works well with iron processes!)

    Don't you have "food grade" powdered gum arabic there in the States? (Mine was so; maybe that makes the difference?)


     
  11. R Shaffer

    R Shaffer Member

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    How about the powdered stuff that Bostick & Sullivan sells? It is expensive. I'm just curious as I use their 14 baume and I am very happy with it.
     
  12. GumPhoto

    GumPhoto Member

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    Sorry, I guess I haven't tried it. If its from B&S, though, I'm sure it must be good. I wish I had read this yesterday - I just placed an order with them!

    I like using the powder stuff because I can make it super-thick. Basically, I force as much into solution as I can get. No idea what the baume is, but it is essentially a saturated solution, if that term can be used for a colloid.
     
  13. michael9793

    michael9793 Member

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    Peter I have read your work on that site and want to say thank you for all the work you put into it. I'm going to start doing 4 color dichromate printing and your advise was very helpful. I have been printing Pl/Pt for a long time and need something a little different to spark some new interest. The thing is I have been shooting in B&W for 40 years and looking for color work is also a new challenge.
    regards
    Michael Andersen.