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  1. #31
    holmburgers's Avatar
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    Quote Originally Posted by Hologram View Post
    I just had a look at FR 886,716. Gum is not mentioned there. The colloids listed in that patent are: gelatin, methyl cellulose and PVA/methyl cellulose.
    Methyl cellulose, aka carboxy methyl cellulose or CMC gum is a commonplace ingredient for ceramicists and is used in glazes. It'd be fantastic if DAS and CMC gum could potentially used in a gum-bichromate like process. I'm curious to know more about Kees' synthetic colloid as well.

    Also, does anyone know if PVA refers to polyvinyl acetate or polyvinyl alcohol?? I would assume PV-alcohol (Elmer's glue), but I'd like to be sure.
    Last edited by holmburgers; 02-24-2013 at 06:45 PM. Click to view previous post history.
    If you are the big tree, we are the small axe

  2. #32

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    Quote Originally Posted by holmburgers View Post
    Methyl cellulose, aka carboxy methyl cellulose or CMC gum is a commonplace ingredient for ceramicists and is used in glazes. It'd be fantastic if DAS and CMC gum could potentially used in a gum-bichromate like process. I'm curious to know more about Kees' synthetic colloid as well.

    Also, does anyone know if PVA refers to polyvinyl acetate or polyvinyl alcohol?? I would assume PV-alcohol (Elmer's glue), but I'd like to be sure.

    Hi, I could not resist to do some quick tests with DAS and methyl cellulose. A fairly thick 2,5% methylcellulose solution was 1:1 mixed with standard 3% DAS. Mixed in some lampblack watercolorpigment. This mix was applied on a gelatin sized and hardened watercolor paper. It was difficult to apply an even coating, much more difficult than with gum. After some testing I found out that a 15 sec (!) exposure under a bank of UV TL was sufficient. The methylcellulose shows a very heavy stain after exposure. The print can not be developed in cold water, nothing happens there. I found out that a rather warm bath or even a stream of warm water (±40°C) like with carbon worked well. So, yes it works!

    When speaking of PVA I allways refer to PolyVinyl Alcohol, available under various brand names. I'm using Mowiol. Polyvinylacetate (PVAc) is very different and not suitable for pigment/colloïd printing because when dry, as far as I know, it is not water soluble anymore. It can be used as a sizing for paper. PVA works with DAS but not that good in my testing. I have found very good hardening and extemely high sensitivity with some polyvinylpyrolidones (PVP).

    Kees

  3. #33
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    Awesome Kees, thanks for doing the experiment!

    CMC gum is an oft overlooked material I feel, and here you've shown that it has potential for printing processes. It's cheaper than dirt and fairly easy to work with. It doesn't set like gelatin, which is both a good thing when you consider you don't need heat, and a bad thing when you realize it has to dry flat.

    Thanks too for clarifying the PVA issue.
    If you are the big tree, we are the small axe

  4. #34

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    Quote Originally Posted by gmikol View Post
    Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

    Best of luck...

    --Greg
    I suspected as much and having spent a few days (Far too short in my opinion) with Kosar's Light Sensitive Systems I even have some insight as to why. Though having read Kosar I think it may be possible to implement a carbro-like process by producing a dichro or diazo based process that is sensitive to visible light. Then you would either print on dichro/diazo coated paper and after exposure marry it to tissue (A la a mariotype) or expose the sensitized tissue directly in the enlarger. Unfortunately DAS doesn't seen to be in the class of diazonium compounds that are or can be made sensitive to visible light but until I can find such a compound I can experiment with it and try to dye sensitize dichromates.

    As an aside if anyone hasn't already read Kosar buy, borrow or steal a copy. It is a fount of fascinating information and potential new paths of inquiry.
    Last edited by Orioes; 03-10-2013 at 06:43 PM. Click to view previous post history.

  5. #35

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    Hi
    Is there still a group purchase option available for this DAS sensitiizer?
    I am looking to purchase 1KG if possible.
    thanks
    David

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