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152[PPLetterpress] Re: Exposure/washout units

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  • Harold Kyle
    Oct 4, 2001

      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
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