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How to convert 3M - UV exposure unit

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  • Erik Desmyter
    ... The UV lights in my 3M UV exposure unit are Philips TLD 15W05 . Are these correct UV lights for letterpress photopolymers (somebody told me the frequency
    Message 1 of 4 , Aug 22, 2001
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      Harold Kyle wrote:
      > All this to say that if you care about the quality of your (expensive)
      > photopolymer plates, you should not use an exposure unit for alt-process.
      > You need a vacuum and you should try to use kreene, which will minimize
      > light distortion. I sell the kreene at $1 per square foot. Kreene needs to
      > be replaced periodically because it loses its plasticity and can soil up.
      > Oh, and I also have a few extra vacuum pumps laying around

      The UV lights in my 3M UV exposure unit are "Philips TLD 15W05". Are these
      correct UV lights for letterpress photopolymers (somebody told me the
      frequency could be wrong)?

      If I would convert the unit I can take out the existing glass plate very
      easy and then would have to go for the kreene & vacuum stuff. What distance
      would you typically have between UV-lights and the kreene?

      (For new listmembers you can see the unit at http://groups.yahoo.com/ (with
      your Yahoo! ID and your password) and then go to PPLetterpress were you will
      have access to the Photo Album of this list).

      Rgds,
      Erik
    • Harold Kyle
      ... An lighting and electrical store with be more authoritative than me, but I use Philips TL series lamps in my platemaker. Mine are TLK and a different
      Message 2 of 4 , Aug 24, 2001
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        >
        >
        >
        >The UV lights in my 3M UV exposure unit are "Philips TLD 15W05". Are these
        >correct UV lights for letterpress photopolymers (somebody told me the
        >frequency could be wrong)?
        >
        An lighting and electrical store with be more authoritative than me, but
        I use Philips TL series lamps in my platemaker. Mine are TLK and a
        different wattage. TLDs will most likely work for you.

        >If I would convert the unit I can take out the existing glass plate very
        >easy and then would have to go for the kreene & vacuum stuff. What distance
        >would you typically have between UV-lights and the kreene?
        >
        The platemakers I have seen have had 1.5 to 2 inches distance between
        the lights and the plate. Too close, and the shoulders of reverse type
        etc. will fill in; too far and the shoulder will be too vertical and
        weak. No one has ever really confirmed this belief of mine, though. Have
        people had luck with other distances?

        Your conversion is more of an overhaul. You'd have to add quite a bit of
        hardware to make it work with kreene and a vacuum. As long as we're
        converting platemakers for polymer, you might find it easier to convert
        an old offset platemaker by replacing its light source with the fixtures
        in your contact frame & kreene. Just a thought.

        Harold Kyle

        --
        ~ ~ ~ ~ ~ ~
        Boxcar Press
        Fine Printing and Binding ~ Digital Letterpress Supplies
        640 Fellows Avenue ~ Syracuse, NY 13210
        www.boxcarpress.com
        ~ ~ ~ ~ ~ ~
      • Gerald Lange
        Dear Harold This is exactly what happens during photopolymerization. With longer exposure times the photopolymer begins to fill in (just the opposite of what
        Message 3 of 4 , Aug 24, 2001
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          Dear Harold

          This is exactly what happens during photopolymerization. With longer
          exposure times the photopolymer begins to fill in (just the opposite
          of what you would common-sensical presume). Reverses and solids
          require less exposure, thus are given more vertical strength.

          But what is interesting here (in your statement) is the possibility,
          with one of these units, of being able to mechanically modify exposure
          rates independent of exposure time!!!


          > The platemakers I have seen have had 1.5 to 2 inches distance between
          > the lights and the plate. Too close, and the shoulders of reverse type
          > etc. will fill in; too far and the shoulder will be too vertical and
          > weak. No one has ever really confirmed this belief of mine, though. Have
          > people had luck with other distances?
        • Joel Benson
          Just to backtrack a bit: I m attracted by rumors of machines available cheaply. Could someone tell me what a generic name or description might be for a
          Message 4 of 4 , Aug 24, 2001
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            Just to backtrack a bit:

            I'm attracted by rumors of machines available cheaply. Could someone
            tell me what a generic name or description might be for a "convertable"
            UV exposure unit? I'm looking for some names (or model types) or terms
            I could use to describe what I am looking for when calling a used
            equipment dealer or perusing ads. I am familiar with the units made
            specifically for photopolymer, but not with the other machines used by
            the other printing industries.

            Joel Benson
            Dependable Letterpress
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