Titanium dioxide pigment sensitizing?

Discussion in 'Alternative Processes' started by menglert, Jun 24, 2007.

  1. menglert

    menglert Member

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    Hi,

    Would anyone happen to know a method of sensitizing titanium dioxide pigment and processing it?

    This is only a thought and I'm looking to get some input with it. I figured maybe it could be used as another method of making b&w prints.

    Thanks,
    Martin
     
  2. Katharine Thayer

    Katharine Thayer Member

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    Add a little gum arabic to it and sensitive it with ammonium or potassium dichromate (in other words, make a gum print from it). But you'd have to print it on black paper and use a positive to print it with rather than a negative, if you're going to make a black and white print with it.
    Katharine
     
  3. menglert

    menglert Member

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    Thanks for the info. I may be looking into this.

    -Martin
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    It depends on whether it is Rutile or Anatase IIRC, but TiO2 can be made light sensitive and can accept pigmented images. Many years ago, Kodak and others made color images from TiO2 by transferring the pigments to an exposed, charged surface.

    Internally, it was called Electrocolor. I cannot remember a single thing about how it worked though.

    PE
     
  5. Katharine Thayer

    Katharine Thayer Member

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    From the sources available to me (the best source would be Color Index International, but it's not available to me online since I'm not willing to pay the subscription fee) it seems that the titanium dioxide pigment that I assume Martin is talking about, Titanium White (PW6), is Rutile. I'm curious how that changes anything.

    Like any other pigment, Titanium White can be added to dichromated gum arabic (and for all I know to dichromated gelatin as well, since I notice in another thread Martin is asking about carbon and carbro processes) to express a photographic image, but since it's white, it's not much good on white paper. Some gum printers print it on black paper, through a film positive, but the effect is nothing like the usual black and white photo.

    I'm curious what prompted the question in the first place?
    kt
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    TiO2 is light sensitive itself and can form an image through electrostaic charge and light exposure. IDK the details, but I have seen some beautiful full color images made this way.

    PE
     
  7. AgX

    AgX Member

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    So you mean not only white on black in contrast to black on white Xerogaphy, but also without using a charged light-sensitive drum etc., but using the light-dependend chargibility of the pigments?

    I got some literature on electrophotography. Shall look it up the next days.
     
  8. Jeremy

    Jeremy Member

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    Katharine,

    Any suggestions on a black paper to print on? I've been curious about printing positive white images these last few months.
     
  9. Katharine Thayer

    Katharine Thayer Member

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    Hi Jeremy,
    The only paper I've actually tried is Arches Cover Black, which works okay if you size it well (I sized it with acrylic medium) but I didn't like the coarse texture of it, so I was working on finding a smoother paper, before I got busy with some other project and never got back to it.

    At first I tried coloring regular hot-press watercolor paper black with black ink, but that didn't work at all. If the ink was really waterproof, then it made a slick rubbery surface that the gum wouldn't stick to, and if it wasn't really waterproof, then it came off when I started coating the gum emulsion onto it.

    Then someone suggested Stonehenge paper which comes in black, and I ordered a couple of sheets but have never got around to trying it. That's the paper I'd suggest starting with. Even though I've not used the black myself, I have printed gum on white Stonehenge, and found it a good enough paper for gum. It's $1.87 a sheet in the Daniel Smith catalog, look under Rising Stonehenge. Good luck, and sorry for such a long answer to such a short question,
    Katharine
     
  10. Katharine Thayer

    Katharine Thayer Member

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    PE,
    Are you saying that both Rutile and Anatase are photosensitive, or is this the quality that depends on which form it is?
    kt
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    IIRC, one is and one is not. But this is a matter of degree, again IIRC.

    It has been since about 1970 since I saw any of this in practice. There are loads of EK patents on this in that era.

    PE
     
  12. menglert

    menglert Member

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    Thanks for all the excellent info thus far from everyone. Honestly I didn't expect so many responses. The idea came about because I was reading about the different metal salts used for Alt printing and wondered if titanium had something to offer. Then came across the pigment. Thus, I thought it might be fun to play around with.

    -Martin
     
  13. z-man

    z-man Member

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    pigments and photosensitivity

    suggest that you get with a good comercial custom silk screen shop and find out what does and doesnt work

    years ago when i was a photomechanical artist in the nyc adv biz i worked with AGA-Afordable Grafics Associates, run by a 6 ft 6 in latvian by the name of Ugis -if you can find him you will get your questions answered

    i worked in the boston adv biz and worked for Identicolor-multiple sensitised layers each custom colored and built up one on top of the other on a transfer sheet so that they could be rubbed down on to the mocked up packageing used in a presentation-lets say coumbo yogurt-so you do 6 different color versions of the same design

    i can tell you that each pigment can increase or decrease the sensitivilty of an emulsion and that each different vendors version of a standard pigment is different

    these are uncharted waters and you must do this for yourself and find out what works with what you got-and the next time you re up all your times and proportions will change

    buena suerte
    y
    vaya con dios
     
  14. fparnold

    fparnold Member

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    For the purpose of oxidation chemistry, there's a lot of recent literature on using anatase thin films/nanoparticles sensitized with catecholates chemisorbed to defect (5-coordinate) sites on the surface. These are UV sensitive, and maybe you could use this trait to essentially bleach out the pigment where the negative is transparent. This is being used to make self-cleaning windows, amongst other apps.

    If you have access to an academic library, I'd start with the ACS journals such as J. Phys. Chem. This reflects my bias (chemist), as I find the physics journals hard to read and a little too abstract. Look up articles in the last 2-3 years by Larry Curtiss for a start.
     
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  15. smieglitz

    smieglitz Subscriber

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    Jeremy,

    Here's a link to a gum bichromate print experiment I did on Arches Cover Black a few years ago. IIRC the print was made with a layer of titanium white pigmented gum followed by a layer pigmented with DS Interference Blue. I uploaded it to the hybridphoto.com site since it was printed from an inkjet negative.

    Joe