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Re: [PPLetterpress] shadow printing problem - advice??

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  • nagraph@ekiva.net
    By setting too hard I mean that the roller(s) are riding the type/printing surface with too much pressure, or expressed another way, that an ink stripe if
    Message 1 of 7 , Dec 25, 2007
      By setting "too hard" I mean that the roller(s) are riding the
      type/printing surface with too much pressure, or expressed another way,
      that an ink stripe if measured on the plate rather than a roller setting
      gauge is too wide. When using anybody's base and plate system, a roller
      setting gauge is a relative gauge only and not the final decision maker.
      The only product I'm aware that is truly accurate to .918 + or - .0005 is
      new foundry type. Since you are using a commercial plate and base system
      with an intermediary of an adhesive to keep the plate attached to the
      base, I can almost guarantee that an accurate stripe on a roller setting
      gauge is only a close approximation of where you want to be, so the final
      determination of roller setting should be what the rollers actually ink on
      a mounted plate. I don't know if you use a roller seting gauge or not, but
      take that into consideration.

      Another source of a hard roller setting are rollers that have hardened
      past their relative letterpress softness of around 16 for composition to
      18 to 22 for synthetic rubber. When we measured the rollers on all the
      presses at the S.F. Center for the Book last week, all were at 27 and
      above on a durometer scale with some around 40 or higher. A hard roller
      does not transfer ink that well, and as it ages, there tend to be surface
      irregularities that may not be detectable to the eye. Thus a cold roller
      will not work as well as a warm roller, especially as it ages. Not seeing
      the situation at hand, these are at best somewhat educated guesses about
      your problem.


      > fritz,
      > yes i usually use just 2 rollers, but put the third on when this problem
      > arose and it didn't seem to make a difference. i also use the bare
      > minimum of ink so as to keep my colors consistent from one run to another.
      > i am not sure what you mean by "rollers set too hard", that may be a
      > solution if you can clarify?
      > thanks, jill
      > nagraph@... wrote: While the other
      > suggestions as to the remedy for your problem are
      > worthwhile and valid, I'm concerned about "The ink also tends to
      > build up and move around on the text as well." That may imply too much
      > ink coupled with too tight or hard a roller seting to the plate. Adding
      > ink to alleviate a ghosting problem will aggravate it, and rollers set
      > too hard will strip more ink off each roller, and you are using all three
      > rollers? All too many C&P users use but 2 rollers, not thinking the
      > reasoning through for 3 rollers. Any 2 roller press, even Miehle
      > Verticals and Heidelbergs, even with vibrators, work at an inking
      > handicap on certain forms with only 2 rollers.
      > Fritz
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