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  1. #1

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    Cyanotype on Transparency Film

    Cyanotype diapositives seem to be currently of interest: if a flexible substrate (plastic film) is acceptable, rather than a rigid one (glass), then I'd recommend trying the transparency films (e.g. from Pictorico or PermaJet) intended for making d*g*tal negatives - they take aqueous iron-based sensitizer solutions very well, and the zeolyte coating holds the image nanoparticles without 'bleeding'.

    Six years ago, when I was testing cyanotype negative-making in camera, I also made one or two diapositive contact prints on Pictorico OHP transparency film coated with my New Cyanotype sensitizer. Tonalities were very good, the only problem was in laying down the coat evenly: my usual glass rod coater was impossible, suffering horrible friction on the ceramic-treated surface of the film. A squeegee or foam brush was better - but the example below still shows obvious imperfections. See attached scans, which were made in transmission mode.
    I have long been meaning to try PTFE for a spreader rod ...

    One thought about using plastic film as a substrate for alternative printing: it is presumably (I haven't tested) much more dimensionally stable than cellulose paper under wet processing - so might prove useful to those who favour multiple coating and developing for their image-making. If it works for new cyanotype, there is no reason why it should not also work for platinum, palladium and other siderotype processes. It also has the advantage that it can be used 'out of the box' with no pretreatment at all.

    Mike
    Attached Thumbnails Attached Thumbnails Cyanodiapos003.jpg   Cyanoneg002.jpg   Cyanoneg003.jpg  

  2. #2

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    I have wondered if you could make true contact printed cyanotype slides using ink jet transparency media, but was worried that it might not have enough "tooth" to hold the solution, and also how it would hold up in the projector. You appear to have solved mystery one for me, now I am going to have to mount a piece of this stuff, draw on it and drop it in the projector and see what happens. This could be a really fun way to make slides that would be quite unique. Thanks.
    "Would you like it if someone that painted in oils told you that you were not making portraits because you were using a camera?"
    "Shouldn't it be more about the joy of producing and viewing the photo than what you paid for the camera?"

    Me

  3. #3

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    I've tried this too, but watched as the blue image ultimately flake and run off the sheet in the final wash. Any notes on how you got it to stick?

  4. #4

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    Mike,
    It is a pleasure! I have known about your work for many years, but never befor had direct contact. A number of years ago, I was working with Pt/Pd with an open mind for anything transparent. I did try Pictorico OHP among other brands of inkjet transparencies. I had huge problems with even coating. Foam brushes and glass tubes left streaky, uneven coatings. The best I did was to dip coat the transpalency film in a troth of Pt/AO. This an expensive way to go! Even then, the results were poor as regarding even coating.
    Since then I have "fallen in love" with glass and no longer have an interest in imaging on plastics.
    Regards,
    Bill

  5. #5

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    Greetings, Bill, and thank you for sharing your experience of coating Pictorico with Pt/Pd sensitizer. It seems to take and hold these iron-based processes well. But I'm still a devotee of fine paper so, like you, I'm not very interested in printing on plastic, either, but there is something pleasantly subversive about printing a 19th Century process on a 21st Century material!

    I thought it worth mentioning here in case someone is keen enough to follow it up with more testing. The coating unevenness we both experienced is more painfully evident because we are viewing the densities in transmittance - when normally lighting an image in reflectance, any unevenness tends to be 'buried' in the depths of the paper. It should be feasible to coat with cyanotype by total immersion - but I agree this gets highly uneconomic for Precious Metal sensitizers! Maybe I'll put this back on my agenda.

    Having now dug out my notes of 6 years ago, I found that a Teflon (PTFE) rod makes an acceptable coating instrument for Pictorico - provided one can get it straight enough - smooth and clean with no friction. I also see that I made a New Chrysotype on Pictorico - which came out a neutral, slightly bluish black - quite different to the result on paper. Whatever the surface coating is (one manufacturer says "ceramic"), it is quite a different substrate to cellulose for making siderotypes, possibly due to a very different concentration of adsorbed water and the (presumed) absence of sizing agents. Best wishes,
    Mike

  6. #6

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    Hi again,
    I should also mention that, with Pictoico Tansparency Film, absorption of Pd/AO is so fast that, if the sensitizer is poured onto the film, about half of it will be absorbed immediately, leaving a dark place where the puddle was. This is why I went to dip coating. But that has to be done quickly and evenly, hard to do by hand.
    Bill

  7. #7

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    Have found some new and interesting information over the past week in my search for polymers that will actually strongly adhere to acrylic or PETG sheets and how inkjet coatings work on non porus surfaces. I came across several companies that do a lot of engineering and development work concerning formulations of inkjet coatings.

    A company called Internatiional Specialty Products has some very interesting products and a great PDF document on specific formulations for inkjet coatings to be used on different types of substrates

    http://online1.ispcorp.com/en-US/Pag...40&prdId=72439
    http://online1.ispcorp.com/Brochures...nkjetguide.pdf


    Another company is W. R. Grace & Co. which also has products specifically targeted at the inkjet coatings.
    http://www.grace.com/EngineeredMater...o/Default.aspx

    The experiences demonstrated with coating Pictorico and how fast it absorbes the photo emulsion may be due to the percentage of hydroscopic nano particles in the coating. If a custom coating could be made that had a slower absorbtion rate to allow hand coating, which would be really nice product to have.

    Cheers,
    David

  8. #8

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    Many thanks for those links, David, they provide some insight into what constitutes these absorbent surfaces, which I feared might be totally shrouded in commercial secrecy. Colloidal, porous, silica hydrogels, eh? Possibly with some addition of aluminium oxide/hydroxide (the mineral Boehmite). All rather different from our much-loved - but (to judge by recent posts here and elsewhere) very wayward - cellulose papers!

    Another possible answer to our uneven absorption problem, that Bill describes, might be to increase the viscosity of our coating sensitizer solutions - by adding some hydrophilic polymer, such as the PVP (polyvinylpyrrolidone) which we now know is used to bind the silica coatings themselves.
    Good wishes
    Mike

  9. #9

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    Quote Originally Posted by Mike Ware View Post
    Another possible answer to our uneven absorption problem, that Bill describes, might be to increase the viscosity of our coating sensitizer solutions - by adding some hydrophilic polymer, such as the PVP (polyvinylpyrrolidone) which we now know is used to bind the silica coatings themselves.
    Mike, Happy to share with the community and hopefully get into the hands of those that having a stronger chemistry background than I do. Besides why should the inkjet folks have all the fun.

    I wonder if silica itself could be used in the sensitizer solutions to increase the viscosity. I have samples of colloidal silica, fumed silica, PVP, PVP-P(Crosslinked PVP) coming this week so and will be having fun with new experiments to work on over the next few weeks.

    My personal hope is that the learnings from the inkjet industry can also be applied as an alternative to gelatin sizing for paper.

    Cheers,
    David

  10. #10

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    Quote Originally Posted by DPVisions View Post
    My personal hope is that the learnings from the inkjet industry can also be applied as an alternative to gelatin sizing for paper.
    Cheers,
    David
    I'm delighted to learn that you're going to experiment with C19th processes on C21st materials! It will be interesting to see how porous silica behaves as a substrate.

    Gelatin is certainly bad news for platinum printing: as a polypeptide (protein) it contains aminoacid groups that bind strongly to Pt(II) and make it very difficult to reduce to Pt metal. This is discussed on my webpages. Willis avoided gelatin-sized papers for his platinotype, and used alum-rosin sized papers (as now used in Weston Diploma Parchment). The modern internal sizing agent used in most papers is alkylketene dimer (AKD), which seems compatible.

    Mike

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