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  1. #1
    holmburgers's Avatar
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    Photogravure on rubber to make photographic stamps

    Howdy,

    I'm thinking about the possibility of making photographic stamps, and ultimately, color separation stamps. It could be like a poor man's version of dye-transfer printing.

    The steps would be similar to typical photogravure except that instead of etching a copper plate you'd have to find a suitable chemical to "etch" rubber.

    I know nothing in this realm of chemistry, but does anything come to mind that might be suitable? What dissolves rubber?

    Sure this is a hare-brained idea, so feel free to crush my dreams if there's cause to do so, but I'd greatly appreciate any constructive comments.

    Thanks,

    Chris 'holmburgers' H.

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    Thats interesting, can't wait to hear more

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    Rubber stamps are made by impressing with heat and pressure a rubber sheet into a mold which is the reverse of what you want. There must be a rubber stamp manufacturer close to you which could give you a better description of the process.
    Richard

    Why are there no speaker jacks on a stereo camera?

  4. #4
    holmburgers's Avatar
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    Well I understand how stamps are made, but that's not exactly what I'm interested in doing. I'm proposing a method to produce them thru photographic means. However, perhaps heat would have to play a role. (acid maybe?)

    Like in photogravure, you'll apply the image to the rubber either on a gelatin tissue, gum emulsion or something like this, and then develop with whatever chemical will eat away the rubber where there is less of the gum/gelatin/bitumen (I have no idea really), etcetera etcetera.

    Alexhill.... I can't wait to hear more myself

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    I know a lot of people who hand-carve rubber stamps, as opposed to using the vulcanized commercial offerings. photogravure implies tones, not solid prints, which is what stamping produces. I have seen some incredible tonality done by approximating a half-tone effect by carving, but it cannot be too fine or the ink blocks the detail.

    A process clear/black image and a UV curing medium might work. If you can find a way to do that, then adjusting the image (posterize to 2-3 levels) would give you a set of stamps for registration printing. That's possible by hand carving, but a lot of work.
    I feel, therefore I photograph.

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    Schlapp's Avatar
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    Isn't there a light sensitive film one can get? Not sure how one would 'etch' the rubber tho

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    holmburgers's Avatar
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    It seems like the light sensitive part would be easy, just need what grahamp said, a "UV curing medium". I don't know much, but would gum bichromate (minus pigment) be suitable? Admittedly, I don't know enough to be throwing around terms, but I know enough to say that it would require a emulsion that hardens in proportion to the exposure it receives. Then you could wash/develop it away, exposing the rubber to allow the etchant access.

    As for etching rubber, I have no idea, but it seems like any number of things would eventually eat thru rubber. However, if a chemical/acid can eat thru rubber, will there be a 'UV curing medium' that can withstand it? That is the key question I s'pose.

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    Boxcar Press sells photo sensitive plates that are plastic-backed or steel-backed polymer printing plates. If you expose them through a transparent positive, you can ink them, wipe them and print them as etchings (photogravure.) If you expose them through a negative (and a half tone screen) they can be inked with a roller to print the raised image. Either way you will get a positive. The thickness of the polymer and the detail you get are functions of many different things, but it's a pretty straightforward process, if not a simple one. Four plates, exposed through negative color separations and printed with Black, Cyan, Magenta and Yellow, will give you a color image. Voila! You will have re-invented the printing method used by print shops all over the world for much of the 20th century.

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    photo gravure and rubber plates

    I wonder what you are trying to create.If it is true gravure then you have chosen the technically more difficult of all the graphic arts printing processes. Letter press plates had raised metal images that accepted ink. Lithography were stones and later metal plates the accepted ink on the image and the image was transferred by contact the paper Offset lithography the metal plate accepted ink in the image area only the non image area accepted water ( actually a very specific solution called a fountain solution) which was then transferred to blanket usually a rubber type material which then transferred the image to the printing paper .Gravure also called intaglio printing ,the image was receded in the metal call cells and the paper pressed in to it to .Roto gravure were gravure plates spun at high speed and the ink literally thrown onto the paper Roto gravure required both a halftone image and a continuous tone image to get the correct depth in the cell for the ink. It was a highly complicated and specialized operation.. Until web presses were introduced it was the best way to do high speed printing .When webs were introduced they were capable of 70,000 impressions per hour. The average offset press normally peaked out around 10 to 15,000 iph.
    Rubber printing plates used letterpress type plates to form the image ,and as I remember it required an intermediate step to get a reverse depth .Perhaps a film positive was used to create the engraving and the rubber plate pressed directly from that .It was a long time ago that I worked in it .
    Good luck with your project.

  10. #10
    holmburgers's Avatar
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    whitey, thanks for the reply. Your description is encouraging and indeed I found these photopolymer plates on the web after my last post. So, is the half tone screen the key to getting continuous tone? I read the autobiography of F.E. Ives who invented/pioneered the photogravure process (IIRC) and he talked extensively about half tone screens. Hmmm, I think I will have to give this a try!

    rmolson, thank you as well for the overview. I guess I said 'photogravure' for lack of a better understanding on my part of the different processes, but basically I'm interested in this type of printing but looking for a simplified/affordable method. Ultimately, I just want to get into tri-color printing.

    I'm also toying with the idea of using etch-at-home copper circuit boards. Normally you draw the circuit with an acid-resist pen and then etch in acid, but perhaps the acid-resist pen could be replaced by this elusive UV curing medium Just a thought....

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