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42RE: [PPLetterpress] contact frames

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  • Joel Benson
    Aug 24, 2001
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      "Any hints on increasing success with hand washout?

      Katie Harper
      Cincinnati, OH"

      I've only hand-washed a few plates, when the motor in the washout
      machine I was using was broken. I just laid the plate face down on the
      brushes and rubbed, and it worked, but I remember it did weaken the
      small stuff (periods) and I had to re-do at least one of them.

      The thing I noticed is that when you expose your image or type or
      whatever, the polymer is not hardened all the way down to the backing
      material. It is only in the post-exposure that the shoulders and the
      under layers of the type/image are hardened. Consequently, during the
      washout, the shoulders of the type are weak, and easily washed away.

      I think the hardened face of the type protects the shoulders from the
      brush when the bristles are oriented close to 90 degrees to the face of
      the plate and only lightly and evenly touching. This precise
      brush-plate contact is harder to maintain by hand, so it is easier to
      undercut your printing surface, allowing things to wash away or get
      substantially weakened.

      The only hint I can offer is light, careful brushing. However, I can
      think of two possible experiments; perhaps someone has already tried
      these and can comment on their results. First, does washing with cold
      water increase resistance to the bristles, allowing the shoulders to
      hold up better? Second, does the thinner plate material hold up better,
      because the initial exposure may harden closer to the backing material?
      The stuff I use is .028 or something, but I know it comes thinner, like
      .020 or some such. Maybe that makes a difference.

      Now my brain is going to be stuck all day on trying to think of a
      homemade jig for holding the plate flat and light against the bristles!
      If I think of something good, I'll post plans!

      Joel Benson
      Dependable Letterpress
      San Francisco
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