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Re:Processing plates by hand

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  • mossgate
    I have only had a few months experience with photopolymer plates but have found the experience fun, simple & successful. I come from the intaglio perspective
    Message 1 of 12 , Dec 4, 2002
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      I have only had a few months experience with photopolymer plates but
      have found the experience fun, simple & successful. I come from the
      intaglio perspective so this might be subject to further comment by
      letterpress folks. I recently purchased a somewhat neglected
      Vandercook SP-15 but haven't yet had the time to get it up and
      running
      to see how my present technique translates to letterpress.

      For one thing, I am using the type of photopolymer plates that are
      exposed to the sun..."sun plates." I was taught to do my exposing on
      sunny days only, which up to this point I have done. Not a practical
      method for commercial purposes.

      I place my photopolymer plate on a piece of masonite that I backed
      with felt. I place the plate emulsion side up onto the felted
      masonite
      and place my transparency emulsion side down onto the emulsion of the
      pp plate. I place a piece of 1/4 inch glass over the transparency
      and
      clamp the whole thing on four sides.

      I throw a towel over the glass and pull it off once I'm outside and
      ready to expose. Use a watch with a second hand or stopwatch.(Make
      sure no lint, hair, or whatever is sitting on the glass....) I
      expose
      for between 1 minute and 20 seconds to 1 and a half seconds.

      I rince the pp plate under the kitchen faucet using cool to luke warm
      water for only one minute gently scrubbing with a soft bristle brush.
      I then blot the plate with newspaper which leaves no lint and removes
      potential watermarks beautifully.

      I then leave my plate in the sun for several hours before letting dry
      inside for another 24 hours.

      I get very fine detail from my photo images.

      I find that making a transparency that has moderately "thin" blacks
      helps keep the pp plate from washing out(etching)too deeply thus
      holding too much ink when one goes to make an intaglio print. Maybe
      this is not a problem with relief printing.

      Best thing to do is print test strips to understand how exposure time
      and the intensity of the transparency's blacks effect plate detail
      and the printing outcome.

      I have been purchasing my steel backed sun plates from Daniel Smith.
      I'd love to find pp plates elsewhere at a competative price.

      Aurora Oberloh
      Phoenix, AZ
    • Gerald Lange
      ... Hmmm, interesting. This is a problem with relief but in a different way. Would a longer exposure in the sun compensate for thin blacks in regard to the
      Message 2 of 12 , Dec 5, 2002
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        >
        > I get very fine detail from my photo images.
        >
        > I find that making a transparency that has moderately "thin" blacks
        > helps keep the pp plate from washing out(etching)too deeply thus
        > holding too much ink when one goes to make an intaglio print. Maybe
        > this is not a problem with relief printing.
        >

        > Aurora Oberloh
        > Phoenix, AZ

        Hmmm, interesting. This is a problem with relief but in a different
        way. Would a longer exposure in the sun compensate for "thin" blacks
        in regard to the deep etch? Normally the longer the initial exposure
        the shallower the relief will become as the structure begins to fill
        in. Are you suggesting less contrast when you say "thin" blacks? Photo
        images tend to be problematic with relief. Difficult to capture the
        detail in the processing since it requires longer exposure while also
        then having to deal with the problem of the shallower underlying
        structure during printing. Would a shorter exposure with less contrast
        in the grays possibly resolve this?

        Gerald

        Gerald
      • mossgate
        ... blacks ... Maybe ... Photo ... also ... contrast ... First, let me make a correction. I said I exposed my plates for one minute and twenty seconds to one
        Message 3 of 12 , Dec 5, 2002
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          --- In PPLetterpress@y..., "Gerald Lange" <bieler@w...> wrote:
          >
          > >
          > > I get very fine detail from my photo images.
          > >
          > > I find that making a transparency that has moderately "thin"
          blacks
          > > helps keep the pp plate from washing out(etching)too deeply thus
          > > holding too much ink when one goes to make an intaglio print.
          Maybe
          > > this is not a problem with relief printing.
          > >
          >
          > > Aurora Oberloh
          > > Phoenix, AZ
          >
          > Hmmm, interesting. This is a problem with relief but in a different
          > way. Would a longer exposure in the sun compensate for "thin" blacks
          > in regard to the deep etch? Normally the longer the initial exposure
          > the shallower the relief will become as the structure begins to fill
          > in. Are you suggesting less contrast when you say "thin" blacks?
          Photo
          > images tend to be problematic with relief. Difficult to capture the
          > detail in the processing since it requires longer exposure while
          also
          > then having to deal with the problem of the shallower underlying
          > structure during printing. Would a shorter exposure with less
          contrast
          > in the grays possibly resolve this?
          >
          > Gerald
          >
          First, let me make a correction. I said I exposed my plates for one
          minute and twenty seconds to one and a half seconds....that should be
          ..."to ONE AND A HALF MINUTES."

          Beat me with a wet noodle if I'm halucinating, but the less time you
          expose the pp plate the shallower the "etch" will be.

          Everything I do with intaglio would have to be reversed for relief.
          Where shallow plates work best(for me)for intaglio, deeper etched
          plates would be better for relief. Where my inked areas print from
          the depressions of the plates, in relief the ink is on the surface of
          the raised areas of the plate. (I'm just figuring this out in my own
          head.) So first I'd have to reverse my black and white areas on my
          transparency.

          Next, with detailed high contrast line art, I still don't know that
          I'd go with totally intense black. I am getting theoretical now,
          which isn't good, because I know there are folks out there who do
          photopolymer plates on letterpresses quite often and know more than I
          do. But what I feel comfortable saying is that in my experience with
          "sun plates," I haven't ever exposed for more than one minute and
          thirty seconds and have received a deep enough etch for relief. It is
          a matter of whether intense black or a black that looks more like
          purple gray on the transparency would better allow for more detail to
          survive.

          I reduce my black intensity in Photoshop using the "levels" filter
          before printing to a transparency.

          I still would not rince for more than a minute....at least with the
          brand of sun plate sold by Daniel Smith. I do not know who
          manufactures those plates.

          Taking into account variability in the kind of artwork and personal
          preference, test strips are the way to go.

          Aurora Oberloh
          Mossgate Private Press
          Phoenix, AZ
        • Gerald Lange
          ... Hi Hmmm. Works the opposite with relief. The underlying structure begins to grow upward (shallower) as the exposure time lengthens. Seems odd but that s
          Message 4 of 12 , Dec 5, 2002
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            >
            > Beat me with a wet noodle if I'm halucinating, but the less time you
            > expose the pp plate the shallower the "etch" will be.
            >

            Hi

            Hmmm. Works the opposite with relief. The underlying structure begins
            to grow upward (shallower) as the exposure time lengthens. Seems odd
            but that's the way it apparently works. The molecular connections
            between the unexposed and exposed areas of the photopolymer begin to
            link. A process called halation. Useful for halftones and other fine
            detail as the supporting structure is better. The halation process is
            halted by post-exposure. In the old days of photopolymer you needed to
            "back-expose" to ensure the bottom of the plate became an
            anti-halation layer. All sheet based photopolymer now comes all ready
            prepared in this manner. At least that's my understanding of it.

            Maybe there is a washout difference here? If you washout a fine detail
            for too long, such as for instance, a separated rule, it will begin to
            erode at the anti-halation layer.

            I know we are discussing processes that are essentially the reverse of
            each other but this does not make sense to me. Unless, of course,
            everything I think I know about this is completely wrong. Its happened
            before!!!

            Gerald
          • riverrider2
            Thanks to all who replied. The response was decidedly mixed regarding the merits of hand processing. Some fully advocating it, while others advising against
            Message 5 of 12 , Dec 6, 2002
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              Thanks to all who replied. The response was decidedly mixed
              regarding the merits of hand processing. Some fully advocating it,
              while others advising against it. Being the dedicated DIYer that I
              am, I'm going to start by having my plates professionally done, then
              experiment with easy graphics to see how well I can make them on my
              own. If it works, I save money and have unlimited tiem flexibility.
              If not, I trash a few plates. I'll have fun either way.

              Steve
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