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[PPLetterpress] Re: Exposure/washout units

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  • Harold Kyle
    Tom, I had thought, much like you do, that hand-washing would be accurate than machine washing--until I recently switched over to a machine washout. I
    Message 1 of 14 , Oct 4, 2001
      Tom,

      I had thought, much like you do, that hand-washing would be accurate
      than machine washing--until I recently switched over to a machine
      washout. I purchased the machine for better exposure and for
      convenience, but didn't anticipate better washout.

      In fact, the machine washout produces noticeably better plates. The
      main advantage to the machine is its evenness of pressure. You don't
      need to check the plate periodically for unwashed areas because the
      whole plate washes out at the same rate. Corners took notoriously
      long to wash out by hand; now, I don't have to worry about overdoing
      the washout in the center. This isn't such a problem on type, but a
      10% or 5% screen in the middle of your plate will suffer from
      excessive washout. Because its pressure is constant, it doesn't tend
      to wash away isolated dots as easily.

      Since the machine brushes are larger, they also get the plate out of
      the water sooner. Some plates, especially the large (say, 11x17)
      ones, had to remain underwater for 10+ minutes to wash out with a 4x8
      brush. Leaving them underwater so long can cause delamination of the
      plate. Oh, and the machine brushes don't have hard plastic corners
      that can scratch the surface of your plate.

      Handwashing works. Telling the difference between a machine washed
      plate and a hand washed plate (by someone who has excellent
      technique) would be impossible on most small plates. But for large
      plates or ones with isolated dots, light screens, or very small text,
      machine washing works much better.

      Harold Kyle
      www.boxcarpress.com
    • typetom@aol.com
      Thanks Gerald, Your description of the washout machine action is about as I imagined, having only seen one not in operation. My washout time is presently quite
      Message 2 of 14 , Oct 4, 2001
        Thanks Gerald,
        Your description of the washout machine action is about as I imagined, having
        only seen one not in operation. My washout time is presently quite a bit
        longer than others have mentioned, perhaps because I use a very soft brush
        and only very gently agitate. Obviously still some room for experimentation
        here, but my results now are quite consistent and it seems possible to
        control it by hand washing.

        My first question was probably simpler than your answer: just that the plate
        references (such as MK or MLD) don't tell me much unless I am using the same
        source for plates, I think. Would the MK152 be the same as the MS152 I get
        from Gene Becker? Maybe I just need to go back to the various notes Gene gave
        me to see if the answer is there. Similarly, I have had some difficulty
        making comparison with materials supplied by NA Graphics, because the names
        differ. So I thought it might help if I say Gene Becker's Miraclon MS152
        rather than 152 or MS152....

        Regarding toxicity, it sounds like it's a question of skin sensitivity rather
        than poison or carcinogin. I have hand-washed maybe 40 sheets (A3 size,
        297x420 mm = 11x15? cut to innumerable smaller plates) over six years or so.
        No gloves. No noticable skin reaction, no other problems at all (except an
        occasional cut from the sharp edge of the metal backing, of course). I do
        keep the water running slightly (to keep the temperature constant) so maybe
        the concentration is low. Or maybe I'm just not sensitive. So far, it seems
        to me remarkably benign. The very slight odor from unexposed material also
        seems inconsequential to me. UV light, of course, is bad for the eyes (and
        skin as well, I think).

        Best regards, Tom

        Tom Parson
        Now It's Up To You Publications
        157 S. Logan, Denver CO 80209
        (303) 777-8951
        http://members.aol.com/typetom
      • Frank Cabral
        Hello Tom, The orbital washout unit has been the only way I have been able to produce consistently good plates efficiently. The time factor is very important.
        Message 3 of 14 , Oct 4, 2001
          Hello Tom,
          The orbital washout unit has been the only way I have been able to produce
          consistently good plates efficiently. The time factor is very important.
          About twenty years ago, when the photo polymer was just entering the
          market, I was told by salesmen that the plate could be exposed in the sun
          and washed out in a sink with any brush. I spent what seemed and endless
          amount of time discovering only that there are many variables. I built
          things, converted things, nothing I did seemed to have the same results
          twice, or that the plates were just not good enough. I like process, but I
          was always off task trying to find a solution.
          While not quite a glorious epiphany, the machine allowed me to make
          accurate plates, in a short time with not so much guess work. I only had to
          pay attention to the orientation and density of the negative, the suction
          of the vacuum table, cleanliness of the kreene, monitor the wash out, water
          temperature, drying and final exposure to harden the material. The process
          is simple and consistent (generally).
          I like to examine the plate during washout to check that as much
          material has washed away as possible but not so much as to weaken its
          structural integrity , (small bits of the design, or letters that break off
          during printing that you don't notice until you are finished).
          Gerald has a good explanation of the washout process.
          I think Monotype had much more exacting details built into their
          production, and while success at times seems atmospheric the documentation
          they provided would allow you some success. There are just so many pieces
          to pull together and each one requires complete attention to detail.

          If you contact me off list I can send you some plate processing
          instructions for Miraclon/Rigilon, this is the MLD made by Toyoba. They
          also recommend it for crash printing, hot stamping and for pantograph
          masters. I have only used it for letterpress printing.

          Regards
          Frank
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