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Re: [PPLetterpress] Interesting thread at Typophile

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  • Harold Kyle
    ... I had posted into this typephile.com discussion asking Gerald a question which apparently got lost in the 130 posts (interesting discussion, by the way).
    Message 1 of 5 , May 9, 2004
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      On 5/6/04 5:51 PM, "Gerald Lange" <bieler@...> wrote:
      > Of possible interest to some of the members here is a current thread at
      > http://www.typophile.com/forums
      > on Transitions from metal to digital

      I had posted into this typephile.com discussion asking Gerald a question
      which apparently got lost in the 130 posts (interesting discussion, by the
      way). Since the question I asked is probably more relevant to the
      PPLetterpress list, I have Gerald's permission to try striking it up again
      here.

      Gerald had mentioned that photopolymer creates gain of 5% from the original
      artwork, but to my surprise he credited the platemaking process rather than
      the presswork with the increase. I take this to mean that a 1 point line is
      actually 1.05 points on the actual plate.

      The main reason I objected was my experience printing the same plate on
      coated and uncoated paper. Noticeable gain results when the plate has
      sufficient ink and pressure to transfer to the uncoated paper. When
      registered to the film negative on a light box, the artwork appears more
      heavy than the neg under magnification. However, the artwork of the proof
      pulled on coated paper appears to be the same size as the film exactly.

      Theoretically, the 5% gain during platemaking means that a 10 point line is
      10.5 points, which strikes me as counter-intuitive. Wouldn¹t gain in the
      platemaking gain be absolute, and not vary depending on the thickness of the
      line? I'm curious why a 10 point line would increase 0.5 points while a 1
      point line would increase only 0.05. Wouldn't the plate would become convex
      from such gain? This logic would also frustrate halftones, as 5% gain in a
      200 line screen is a big problem.

      At this point, I'm still somewhat curious the origin of this 5% number. But
      I'm especially curious to what extent Gerald and others believe in ink gain
      occurs on press, and how that compares with the gain that occurs during
      platemaking (if such a thing exists!).

      Thanks,
      Harold

      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
    • Regis Graden
      Harold, I don t believe there HAS to be a 5% gain, or for that matter any gain, between the neg and the polymer plate. There CAN be a very slight gain between
      Message 2 of 5 , May 9, 2004
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        Harold,

        I don't believe there HAS to be a 5% gain, or for that matter any gain,
        between the neg and the polymer plate. There CAN be a very slight gain
        between the "art" and film. There definitely is gain between the plate and
        the paper printed, depending on many factors.

        My humble thought,

        Regis

        ----- Original Message -----
        From: "Harold Kyle" <harold@...>
        To: <PPLetterpress@yahoogroups.com>
        Sent: Sunday, May 09, 2004 1:03 PM
        Subject: Re: [PPLetterpress] Interesting thread at Typophile


        On 5/6/04 5:51 PM, "Gerald Lange" <bieler@...> wrote:
        > Of possible interest to some of the members here is a current thread at
        > http://www.typophile.com/forums
        > on Transitions from metal to digital

        I had posted into this typephile.com discussion asking Gerald a question
        which apparently got lost in the 130 posts (interesting discussion, by the
        way). Since the question I asked is probably more relevant to the
        PPLetterpress list, I have Gerald's permission to try striking it up again
        here.

        Gerald had mentioned that photopolymer creates gain of 5% from the original
        artwork, but to my surprise he credited the platemaking process rather than
        the presswork with the increase. I take this to mean that a 1 point line is
        actually 1.05 points on the actual plate.

        The main reason I objected was my experience printing the same plate on
        coated and uncoated paper. Noticeable gain results when the plate has
        sufficient ink and pressure to transfer to the uncoated paper. When
        registered to the film negative on a light box, the artwork appears more
        heavy than the neg under magnification. However, the artwork of the proof
        pulled on coated paper appears to be the same size as the film exactly.

        Theoretically, the 5% gain during platemaking means that a 10 point line is
        10.5 points, which strikes me as counter-intuitive. Wouldn¹t gain in the
        platemaking gain be absolute, and not vary depending on the thickness of the
        line? I'm curious why a 10 point line would increase 0.5 points while a 1
        point line would increase only 0.05. Wouldn't the plate would become convex
        from such gain? This logic would also frustrate halftones, as 5% gain in a
        200 line screen is a big problem.

        At this point, I'm still somewhat curious the origin of this 5% number. But
        I'm especially curious to what extent Gerald and others believe in ink gain
        occurs on press, and how that compares with the gain that occurs during
        platemaking (if such a thing exists!).

        Thanks,
        Harold

        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



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      • Gerald Lange
        Harold I went back through my notebook to see if I could verify this. My initial thinking, as I mentioned, was that this might have been something to do with
        Message 3 of 5 , May 9, 2004
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          Harold

          I went back through my notebook to see if I could verify this. My initial thinking, as I mentioned, was that this might have been something to do with older liquid photopolymer. I did find the technical measurement term for this, "minimum optical density." This, of course, is varied by plate thickness, hardness, formulation, etc. Dmin for short. Dmin has been used by the proponents of filmless plate processing as one of the measures of its superiority. Their other claim, which is much more intriguing, is that photopolymerization is clarified with oxygen. Apparently, without the obstruction of film (and vacuum sheet) more oxygen can get to the photopolymer during processing, providing more fidelity to the image. Don't have much information on this yet. I suppose the imaging device is a tad expensive.

          But I don't disagree that gain is part of the printing process. I think I mentioned that as well, at some point, in the Typophile thread. We all know, through simple observation, that there can be substantial gain in letterpress, whether metal or photopolymer. My comment was intended to say that there was also some measurable gain to the plate prior to presswork. Quite frankly, I'd be more surprised if there wasn't some sort of variable than if there was none at all.

          I'm not certain how that up to "5%" is measured in terms of image gain, at least in the way you have speculated (non-uniform gain), which I don't quite understand. I would think it would be a uniform gain. But since surface area size itself does to some extent control relief patterning, and because there is a certain non-uniformity to that (it's called "wicking" variance I think), could very well be, don't know for sure.


          Gerald


          --- In PPLetterpress@yahoogroups.com, Harold Kyle <harold@b...> wrote:
          > On 5/6/04 5:51 PM, "Gerald Lange" <bieler@w...> wrote:
          > > Of possible interest to some of the members here is a current
          thread at
          > > http://www.typophile.com/forums
          > > on Transitions from metal to digital
          >
          > I had posted into this typephile.com discussion asking Gerald a question
          > which apparently got lost in the 130 posts (interesting discussion,
          by the
          > way). Since the question I asked is probably more relevant to the
          > PPLetterpress list, I have Gerald's permission to try striking it up
          again
          > here.
          >
          > Gerald had mentioned that photopolymer creates gain of 5% from the
          original
          > artwork, but to my surprise he credited the platemaking process
          rather than
          > the presswork with the increase. I take this to mean that a 1 point
          line is
          > actually 1.05 points on the actual plate.
          >
          > The main reason I objected was my experience printing the same plate on
          > coated and uncoated paper. Noticeable gain results when the plate has
          > sufficient ink and pressure to transfer to the uncoated paper. When
          > registered to the film negative on a light box, the artwork appears more
          > heavy than the neg under magnification. However, the artwork of the
          proof
          > pulled on coated paper appears to be the same size as the film exactly.
          >
          > Theoretically, the 5% gain during platemaking means that a 10 point
          line is
          > 10.5 points, which strikes me as counter-intuitive. Wouldn¹t gain in the
          > platemaking gain be absolute, and not vary depending on the
          thickness of the
          > line? I'm curious why a 10 point line would increase 0.5 points
          while a 1
          > point line would increase only 0.05. Wouldn't the plate would become
          convex
          > from such gain? This logic would also frustrate halftones, as 5%
          gain in a
          > 200 line screen is a big problem.
          >
          > At this point, I'm still somewhat curious the origin of this 5%
          number. But
          > I'm especially curious to what extent Gerald and others believe in
          ink gain
          > occurs on press, and how that compares with the gain that occurs during
          > platemaking (if such a thing exists!).
          >
          > Thanks,
          > Harold
          >
          > 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
        • Harold Kyle
          ... I finally got a chance to speak with my technical support at Jet about this. I should mention that he answered his phone in a Biergarten in Dusseldorf. I
          Message 4 of 5 , May 12, 2004
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            On 5/9/04 7:14 PM, "Gerald Lange" <bieler@...> wrote:
            > We all know, through simple observation, that there can be substantial gain in
            > letterpress, whether metal or photopolymer. My comment was intended to say
            > that there was also some measurable gain to the plate prior to presswork.
            > Quite frankly, I'd be more surprised if there wasn't some sort of variable
            > than if there was none at all.

            I finally got a chance to speak with my technical support at Jet about this.
            I should mention that he answered his phone in a Biergarten in Dusseldorf. I
            think he was enjoying Drupa! I asked him about shrinkage or expansion of the
            polymer during processing, and responded with several points:
            - You can never have a plate match exactly the film, there will always be,
            if only at a microscopic level, some variance.
            - During the washout process, the plate's surface expands as it absorbs
            water. The drying process removes this water and serves to restore the plate
            to its original size. A plate that isn't dry enough would be larger than the
            original film's artwork and a plate that's too dry would be smaller--it
            would have contracted.
            - Provided the plate has been dried to the manufacturer's specifications,
            the plate should actually contract slightly. Imperceptibly slightly. He gave
            the example that a 1% dot on a halftone screen would, on the plate, be more
            like a 0.99%. The difference in size is 0.01%.
            - Many other variables are at play, including the color of the plate, its
            thickness, etc. When he gave numbers, he was speaking about the Jet 94FL and
            Jet 94SB.

            So that's Jet's take on the issue. I would be interested to hear how this
            compares to what other manufacturers say. In the meantime I'll tentatively
            plan to sleep more easily!

            Harold


            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
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