Gum quality

Discussion in 'Hand Coated Wet Prints' started by Nicole Hagesteijn, Sep 13, 2015.

  1. Nicole Hagesteijn

    Nicole Hagesteijn Member

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    The last couple of weeks I have been trying to make gum prints, but the gum would not come off. ( not even when using water instead of Kbichromate and not exposing before developing. ) I have been experimenting a lot and now think my conclusion must be that the gum I bought is not fit for gum printing. I am posting here, because I can hardly believe this conclusion to be the right one; does that exist?
    When I dissolve 300 gram of this gum lumps ( very different in size and color) in 1 liter water I end up with a gum solution that has a viscosity of >>>>50 Baume instead of the 12.5 - 14 that should be. I have to add another liter of water to reach the needed viscosity. But then apparently I have a solution that is different in some way from the one needed?
    Has anyone have similar experience with gum lumps?
     
  2. pschwart

    pschwart Member

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    Hi Nicole. There are bound to be some experienced gum printers here. Trying a commercially prepared gum is going to be the simplest way to test this hypothesis. You should be able to get a small bottle from any place selling art supplies. Where did you source the gum you have been using?
     
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    Nicole Hagesteijn

    Nicole Hagesteijn Member

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    gum supplier

    since I live in the Netherlands I purchased my gum from a paintproducing windmill ( really, I am not making a joke )
    It is called Verfmolen de Kat ( paintmill the cat) Maybe gum for paint can be of lower quality?

    Indeed I will try commercial gum when I encounter the same problems with the gum I ordered today. But when that high quality gum also will give these problems I will have to reconsider my workflow as well I guess.
     
  4. pschwart

    pschwart Member

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    Problem-solving is a huge component of alt printing :smile: Using a prepared gum makes sense, especially while you are learning the basics -- you will get a more consistent product, and this will eliminate a lot of variables that can create frustrating problems. Once you have a reliable workflow, you can play with more advanced techniques, but you will have a baseline you can use to better evaluate the results. If a prepared art gum doesn't solve the problem, then there is still work to be done ...
     
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    Nicole Hagesteijn

    Nicole Hagesteijn Member

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    Hoi Philip,
    From Christina Andersons book I got the impression that commercial gum could vary quite a bit in quality as well and for that reason she advises powder or lumps.
    I thought: buying hashab acasia senegal gum must be the surest way to consistent quality. I understand from you, this is not the case?
     
  6. pschwart

    pschwart Member

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    Nicole,
    In "Alternative Processes Condensed" Christina suggests starting with premixed gum (Photographer's Formulary, Daniel Smith, Bostick & Sullivan -- sorry, all in the US), and mixing your own as you become more experienced. I think this is good advice for any alt process -- focus on the basics, then move on to more advanced techniques after you have developed a reliable workflow. If all is well using a premixed gum, then you experience problems mixing your own, you will know that is likely the source of the problem. Best to eliminate frustrations when learning a process. Start with techniques and materials that are known to work, and experiment later. About quality: I would expect packaged products like gum and pigments to be consistent, though quality can vary by brand. This is less true of papers -- these often get reformulated with no notice, and the changes can have a significant impact on alt printing.
     
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    Nicole Hagesteijn

    Nicole Hagesteijn Member

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    Hi Philip,
    Thank you for helping me. I received the new gum lumps, did get a beautiful Amber colored syrup and coated two cyanotypie images with transparant yellow. The gum came off in the highlights !!!!!
    I am in contact with the provider of the bad gum because I want to know if he can explain this big difference.
     
  8. pschwart

    pschwart Member

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    That's good news, Nicole. You probably won't get a satisfactory answer as to why the first gum was spontaneously hardening, but at least you have confirmed the problem and found something that works.
     
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