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Re: [PPLetterpress] Re: printing images on polymer plates

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  • Harold Kyle
    For intaglio work, desktop transparency positives are adequate for processing photopolymer plates, but for the typical letterpress work, you¹ll need real film
    Message 1 of 5 , Jul 6 7:34 AM
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      For intaglio work, desktop transparency positives are adequate for
      processing photopolymer plates, but for the typical letterpress work, you¹ll
      need real film negatives. We have customers using Pictorico on photopolymer
      for intaglio, but Pictorico only works because they are producing positives.

      Letterpress plates need negatives, and only a silver emulsion film will have
      an adequate density. You can get real film at a local service bureau. Your
      experiments in desktop negatives will likely be costly (the plates aren¹t
      cheap) and error-prone.

      When you ask about ³continuous tone,² I imaging you¹re thinking of using
      stochiastic or random dot screening for your artwork to give this effect.
      From what I¹ve seen, continuous tone work on photopolymer works best with
      intaglio printing. If you¹re printing relief, it¹s much more predictable for
      you to use a halftone to create tonal images. The DPIs that you could use
      (with film) range from 85 to 150, with 100 being average. The higher the
      DPI, the more likely the plate will plug up with ink and print muddy.

      Good luck!
      Harold


      >> > Laser Printer? Inkjet?
      >> >
      >> > Has any one used Pictorico to print transparencies for this purpose?


      Boxcar Press
      Fine Printing / Digital Letterpress Supplies
      Delavan Center / 501 W. Fayette St. / Studio 222 / Syracuse, NY 13204
      315-473-0930 phone / 315-473-0967 fax / www.boxcarpress.com



      [Non-text portions of this message have been removed]
    • Ludwig M. Solzen
      Liz Real continuous tone reproduction in print, still has to be invented. There have been numerous experiments, however, to accomplish a similar effect—in
      Message 2 of 5 , Jul 7 4:45 PM
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        Liz

        Real continuous tone reproduction in print, still has to be invented. There
        have been numerous experiments, however, to accomplish a similar effect—in
        fact, all halftone (or autotypical) reproductions are such an attempt.

        The best results you get with intaglio printing, because of its intrinsic
        quality of taking and adding ink gradually, and hence printing at different
        densities at a time. That is, the screen dots—which (in conventional offset
        and letterpress halftones) otherwise build the image and its different tones
        of grey—in an intaglio screen are in no way relevant to the image itself:
        they are just there to help to keep the ink where it should be while inking
        (cleansing) the form. They do not show up in the print—or only a
        little—because the (dampened) paper, soaked with the ink of all those tiny
        dots, compensates for the screen. So, the smaller your dots, the better.

        The traditional way of making a heliogravure (which is the proper term for a
        photographic intaglio reproduction), is by exposing a sheet of paper, coated
        with a light sensitive emulsion, through (1) an intaglio screen, (2) the
        continuous tone photo positive one wants to reproduce. Afterwards this sheet
        is transferred unto a copper plate, which is subsequently washed and etched.
        The process is difficult and cumbersome and I am still looking for the exact
        formula for the emulsion. I did some promising experiments, though, with
        photopolymer plates.

        You could use aquatint resin powder for the screen, in case you had the
        right emulsion and would use copper — the resin cannot be applied unto a
        photopolymer plate, of course. Sure, you could scan an aquatint screen and
        use this scan as your ‘handmade’ intaglio screen. Too, you could use yet
        another type of screen. You cannot just use the printer’s screen, or one you
        apply in PhotoShop to the image, doing only one exposure afterwards. I made
        a typical intaglio screen, being composed out of little black squares, as
        tiny as the raster elements of the output device, about 21 µm, at a
        resolution of 3600 dpi, with one square being one pixel. Real litho film,
        that is. I could have output the screen myself, as well, on my 600 dpi laser
        printer, in which case the resolution of the digital image should have been
        600 ppi. The resolution is fine enough and lots of easier to handle while
        exposing than the 3600, but homemade transparencies are simply not dense
        enough for being used as a stop-out raster screen. If you do, make sure you
        print them with a laser printer, not with an inkjet.

        The inkjet, you could and should use for the second film needed, your image.
        This should be printed fine enough, e.g. with Pictorico, an Epson or yet
        another device yielding photorealistic images. Too, you could directly use
        your wash drawing made on a transparency or glass plate. If you would prefer
        to print a digital image, make sure it complies to the requirements which
        apply to all graphic imagery: proper ppi (2×lpi of output raster screen),
        right contrast, correct grey balance &c. The blacks (shadows) should be
        maximum 75 percent, the highlights minimum 5 percent. Best print grey or
        composite grey, that is no separated or other colour images. If you would
        use a laser printer, first convert your image to a 1bit-TIFF bitmap, using
        PhotoShop’s ‘Diffusion Dither’, at the highest resolution of your printer.
        (Inkjet screens are always stochastic, those of laser device are never (?).
        With ‘Diffusion Dither’ you delude the printer and have the software do the
        ‘stochastic’ RIP.)

        First expose the photopolymer plate through the raster screen film you made
        or got from your service bureau. (You can use this screening film over
        again, so worthwhile to have one made on real dense film indeed). Only after
        that, expose the plate through the transparency print of your image.
        Exposure times, as always, should be tried out. Now process the plate as you
        would for letterpress: wash out, dry and post-expose. Ink and print as a
        normal intaglio plate on your hand press.

        If you would still have some questions, I’m always pleased to be of service.

        Sincerely,

        Ludwig
      • Elizabeth Gross
        Real continuous tone reproduction in print, still has to be invented. There have been numerous experiments, however, to accomplish a similar effect—in fact,
        Message 3 of 5 , Jul 8 8:22 PM
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          Real continuous tone reproduction in print, still has to be invented.
          There
          have been numerous experiments, however, to accomplish a similar effect—in
          fact, all halftone (or autotypical) reproductions are such an attempt.

          The best results you get with intaglio printing, because of its intrinsic
          quality of taking and adding ink gradually, and hence printing at
          different
          densities at a time.

          Elizabeth Ann Gross
          Deer Tree Press
          eahalegross@...

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        • Mark Attwood
          Liz, I too do mostly hand printed lithography, and some letterpress on a vandercook, and I think if you are looking for ways to get great washes, that
          Message 4 of 5 , Jul 12 2:07 AM
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            Liz,

            I too do mostly hand printed lithography, and some letterpress on a
            vandercook, and I think if you are looking for ways to get great
            washes, that lithography, possibly using photo plates is the way to
            go. Letterpress just doesn't like tonal stuff! I have done some photo-
            litho stuff that we scanned in, and output stochaistic positives in 2
            greys and a black that worked really well, and looked "continuous
            tone" although it wasn't.

            Mark Attwood.
            The Artist's Press



            On 6 Jul 2006, at 05:23, eahalegross wrote:

            > I have just opened Deer Tree Press in Philadelphia, PA USA
            > Hello All. I print hand lithography from stones and aluminum
            > plates, letterpress - I have an
            > SP20, and monotypes including over-sized prints on a very large
            > etching press.
            >
            > My questions have to do with how to output negatives to give (the
            > impression of) continuous
            > tone prints using photo polymer plates.
            >
            > I want to make a ppplate using a wash drawing as the starting point.
            > I thought I could scan the drawing and then print it out as a
            > transparency.
            > How high a DPI can I use. Do I have to turn it into a bit map or
            > can I expose an aquatint
            > screen onto the plate over the image? Particular curves in Photoshop?
            >
            > Laser Printer? Inkjet?
            >
            > Has any one used Pictorico to print transparencies for this
            > purpose? It produces a half-tone
            > with very small dots with Inkjet. It appears that there is no dot.
            > (They are used a lot for
            > contact negatives for Non-silver photography.)
            > Thoughts or sources would be appreciated.
            > Thanks, Liz deertreepress
            >
            >
            >
            >
            >
            >
            >
            >
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