"Snow" in ink - Picking or Blinding issue?

Discussion in '1-Color and 2-Color Offset Presses' started by agreer, Apr 7, 2010.

  1. agreer

    agreer New Member

    Joined:
    Apr 2010
    Messages:
    4
    Location:
    Salem, Oregon, USA
    Hi,

    We're working with a 2-color Heidelberg GTO press and one of the units is picking or blinding - it looks like snow in the colored areas. Here is a list of the press specifications we've already checked:

    • Water pH - 4.5
    • Ink Rollers - 1/8" Stripe
    • Kompac - 5/32" Plate Ink Stripe
    • Tried Ink Tack Reducer with no change
    • Blanket is at specifications

    Can anyone shed some light on what to do? We're out of ideas.

    Thanks!
     
  2. Litho

    Litho Member

    Joined:
    Mar 2010
    Messages:
    39
    Location:
    Rochester, Ny
    how is your paper? did you cut it or did you get it already cut down? it could be paper dust from a bad blade. try fanning out and wiping the edges of your lifts with a lightly wet cloth. are you able to close your blanket or does the layout prevent it? if you cant close it without roll ups try applying rubber rejuv to the blanket. it will harden your blanket enough to close it more but you gotta reapply it every few lifts. does the problem still appear when you change stocks?
     
  3. JP 59

    JP 59 New Member

    Joined:
    Apr 2010
    Messages:
    2
    Location:
    East Coast
    Might try weakening the ink to carry more ink film to the sheet. Add 10-15% extender. Good luck!
     

  4. marker

    marker Member

    Joined:
    Apr 2010
    Messages:
    35
    Location:
    florida
    almost sounds like your over loading the ink train and adding too much water to compensate. try a roller swipe and adjust if needed. you should check rollers and blanket for glaze. wipe down with vinegar and type wash in hot water mixture. check packing between plate and blanket. if you do not use underlay packing (plate or blanket) the blanket my be the wrong thickness by even a few 1,000`s.
     
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