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  1. #11

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    First round of testing is complete. Working with synthesized amorphous silica porous silica gel and polyvinyl butyral is was able to get a very nice cyanotype image onto plexiglass/acrylic.

    The silica in this case when dried is white so the coating on the plexiglass has a slight bit of transparency to it. There is one issue that needs to be resolved is that the silica does not maintain an even dispersion within ethanol, so I need to figure a way to do that.

    A 9" square plexiglass sheet was coated with the PVB mixture as if pooring collodion and excess was drained off. Once the plexiglass was dry 1.5ml of cyanotype emulsion was brushed on with very little excess emulsion once soaked in by silica.

    Attached is a transparency scan of the image and the darker spots and bumps/flakes are excess silica from uneven dispersion.

    Putting this into a window or backlight it really glows!!!
    Attached Thumbnails Attached Thumbnails cyanotype - plexi.jpg  

  2. #12

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    A delicately fascinating image, David. It reminds me of some of those plots from chaos theory as well as insect wings. Congratulations on this new technique.
    1.5 ml over 9" square is a specific coating volume of almost 29 ml / square meter - quite comparable with the amount for coating cellulose paper.
    Was this a 'traditional' cyanotype formulation? Can we see a step tablet test next time?

    Mike

  3. #13

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    Mike, you are very close in the origins of the image. It was generated from a IFS or Flame Fractal. For anyone interested the application is called Apophysis. I like to use fractals with extremely fine lines and detail to help evaluate print detail.

    Attached a sample digital step wedge and a 31 step film wedge from a plexi plate that did not coat as evenly but I think still works as a demonstration, mid tones are a bit flat which can be improved in coating and a curve tweak.

    I am following the traditional cyanotype formula and after initial wash to a quick rinse in peroxide to speed of oxidation.

    Cheers,
    David
    Attached Thumbnails Attached Thumbnails cyanotype - plexi2.jpg  

  4. #14

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    David - you might be interested to note that a similar parallel development of using 'fumed silica' to improve the performance of alkaline-buffered papers for palladiotype is currently being reported here:

    http://lists.altphotolist.org/piperm...st/003948.html

    Personally, I never use alkaline-buffered papers in the first place.

    In the 1960s-70s, the major suppliers, Andrews Paper & Chemical Co. Inc., listed dispersions of colloidal silica (a Monsanto Co. product registered as "Mertone") as precoat preparations for blueprint paper, and I think silica was used in one of the Huey Company's most successful blueprint papers (No. 347-6) used for pictorial purposes. The Technical Bulletins nos. 5 & 24 of the Andrews Co might repay investigation - if you can find copies.

    "There's nothing new under the sun!"

    Mike

  5. #15

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    Mike - Appreciate the heads up on the other effort and additional information. Looks like I need to start following the Alt-Photo list and B&S Fourm. Interesting concept of rubbing/polishing fumed silica onto the paper surface.

    The boxes of goodies has arrived, including 500ml of aqeuos colloidal silica stabalized at a pH range of 4 - 7 so that will be fun to try out with the PPVP.

    Cheers,
    David

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