Shopping list for Gum Bichromate; chems, paper, ?starch?

Discussion in 'Alternative Processes' started by Jeremy, Nov 28, 2004.

  1. Jeremy

    Jeremy Member

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    After working with some cyanotypes over palladium I want a little more control and more color options so gum here I come.

    I'm not worried about the brushes and pigments as we have many art stores locally here in the Dallas/Fort Worth area, but the chemicals are a little bit more troublesome.

    I figure there are only 3 things I need to get:

    250 bloom gelatine
    ammonium dichromate
    40% glyoxal solution

    I might be able to find the gelatin in the area, a source may have already been found for the ammonium dichromate, and Bostick & Sullivan has the glyoxal already in 40% solution (after looking at some of the health issues I don't want to deal with it in powder).

    Does anyone have some suggestions in the amount to order for my first time? I was thinking 250g of ammonium dichromate, 250mL of the 40% glyoxal solution, and 500-1000g of gelatine to keep the costs lower for this first order (want to make sure I like the results before stocking up).

    As for paper, I know Clay recommends Whatman's, but I have a lot of stonehenge rising around--has anyone use it for gum and/or gum over palladium?

    Finally, I read in John Carroll's Photographic Facts and Formulas (1976 edition) that:

    "The paper may also be sized with a fairly thick paste of laundry starch instead of the gelatin, and some workers prefer this method." (p313)

    But that's all it says, does anyone have any further info on this method of sizing? I work at a dry cleaners so I can take all the starch I need free.
     
  2. Jeremy

    Jeremy Member

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    kind of funny, but I completely forgot to add the gum to my shopping list!

    Would 500mL of the 14 baume solution from bostick and sullivan be enough to get my feet wet?
     
  3. smieglitz

    smieglitz Member

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    Jeremy,

    500ml gum will go a long way. I'd recommend potassium dichromate rather than ammonium because I think ammonium tends to stain more. Of course, others will debate that but my experience says it is so. 250 gm dichromate will also go a long way.

    My favorite papers for gum are Fabriano Artistico 270#, Strathmore Aquarelle 140# CP, and Winsor & Newton 90#HP. The B&S ossein is good. Glyoxal is debatable...some evidence that it causes yellowing over time. Plus it is nasty. I'd go with formaldehyde if you have the proper ventilation, personal protection equipment and means of disposal. Glyoxal is pretty nasty but since it doesn't irritate as much as formaldehyde, the tendency is to think it ain't bad and I'm afraid some workers handle it carelessly. You might also investigate alum hardeners as an alternative. They are not as effective but my recent tests show they can be adequate for gum printing. I refer to the hardening bath made by Sprint for their rapid fixer as an alternative hardener.

    You might also try canvas hide glue as a size. Works for me unhardened.

    You say you are set on pigments but let me recommend Daniel Smith or Linel watercolors. They are very pure without fillers that can mess up gum emulsions.

    As a final tip, I usually use gum to dichromate in the ratio of 2 parts gum to one part dichromate solution for the base coat. For highlights the ratio can be more like 1:1. And, too much pigment in the mix causes flaking but not staining as is commonly believed. You want a thick gum coat that sets quickly in order to prevent staining from the pigment having too much time to soak into the paper.
     
  4. donbga

    donbga Member

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    Hey Joe,

    Could you post a gun tutorial on gum printing here on Aug? You had some great posts on the B&S Web Board before it got wiped out.

    Don Bryant
     
  5. Kerik

    Kerik Member

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    Jeremy,

    A few thoughts from my experience with Gumovers:

    Avoid glyoxal for hardening. Too many issues with yellowing. I use formaldehyde and it works great. Just use the proper personal protective equipment. Don't know about the paste starch sizing.

    I use both ammonium and potassium dichromate, depending on what I'm doing. I get less contrast and more speed from amm. than pot. I have no problems with staining with either compound.

    As for paper, I've not done gumover with Stonehenge, but my gut feeling is that it would not be the best due to it's absorbency and I've not checked its dimensional stability (ie shrinkage). I get great results with Fabriano Artistico Extra White 140 lb hot press (I also use Rives BFK and Whatmans if I want more texture). Both the artistico and whatmans are very stable w/o the need to preshrink. BFK I usually pre-shrink twice before printing.

    I use the powdered gum that B&S sells and mix it myself at 300 gm/liter. I add a bit of sodium benzoate as a preservative.

    I've had good luck with pigments from Winsor & Newton, Schminke, Daler-Rowney, Daniel Smith, Linel, etc. Be sure to get the highest grade of each brand and not "student grade".

    For coating the gum, I use 6-inch smooth white foam rollers from any paint or home improvement store. You will use up a bit more materials with this approach, but the coatings are perfectly even and smooth every time and the materials are relatively cheap. Brushes work fine too, but I really prefer the rollers.

    Kerik
     
  6. donbga

    donbga Member

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    Kerik,

    I tried the white foam roller technique a couple of weeks ago and got tons of bubbles with my coating, what should I do to prevent that?

    Thanks,

    Don
     
  7. donbga

    donbga Member

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    Jeremy,

    M. Graham watercolors are very high quality tube watercolors and can usually be purchased for less than $5.00 for a 15ml tube. They have no fillers and use pure gum acacia, these aren't student grade watercolors, BTW. I purchased the entire color set from an art vendor on e-bay and ended up paying less than $4.00 a tube. Granted there are probably some colors I will never use but it still represents a very good bargain. I've also used Sennelier and Winsor Newton and been very pleased with both brands. OF course regardless of brand, some colors will stain and fade more readily.

    I have a friend here in Atlanta that purchased some cheap student grade watercolors in tubes, what a disaster those turned out to be for her.

    Don Bryant
     
  8. smieglitz

    smieglitz Member

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    Thanks for the nice comment Don.

    A gun tutorial? "Hey Joe. Where you goin' with that gun in your hand?" Hmmm. Forcing people to use my gum printing method at gunpoint? I'll think about it. You know there actually was an article advocating "gum control" in one of the early issues of the World Journal of Post-Factory Photography.

    Seriously, I'd be happy to share my experience with gum printing and do an extended post here if I can concentrate on it long enough to write it all down. I've really had some splendid results lately with the methods and materials I'm currently using although some of what I would recommend is at odds with other things you might read in books or on the web. I'm having an exhibit opening Friday and the end of semester is closing in so it will be a few weeks before I have time to write such a post. In the meantime, I'd be happy to answer any questions and I'd also direct people to the gum articles and images on the unblinkingeye.com site by Sam Wang and Christine Anderson. They have it all together. There are also some great gum images on the web by Keith Gerling at
    http://www.gumphoto.com/

    All these people are regular contributors to the alt process list.
     
  9. Jeremy

    Jeremy Member

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    Kerik, I did 2 hot water soaks with the stonehenge and didn't have any registration issues with it for cyanotype over palladium so I will just try it out--the only reason I'm asking is that I've got ~40 sheets sitting here :smile:

    How many times can you use the foam roller before having to replace it? Or after washing is it good until you accidentally take a chunk out of the foam?
     
  10. Jeremy

    Jeremy Member

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    Joe,
    Thanks for your post, it reminded me that I could use pot dichro and I still have ~99g left from a 100 gram bag to get me started.

    I also support a longwinded post or article (not too sure how to submit one, but it shouldn't be difficult) summarizing your method of gum printing.
     
  11. donbga

    donbga Member

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    Joe,

    Any information you could share would be great, I'm sure it would be worth the wait.

    Don
     
  12. rhiannonc

    rhiannonc Member

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    I've done sizing with starch. First, I shrink the paper in hot water. After the paper has dried I soak it for 5 to 10 minutes in a 1:3 mix of starch and water and let it dry again. I get the starch from the super market- StayFlo starch. All my friends use this method to size also, and it works better than a spray starch. Most of us have had success with our gum prints using this method of sizing.
     
  13. Gustavo_Castilla

    Gustavo_Castilla Member

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