Water marks through image area

Discussion in '1-Color and 2-Color Offset Presses' started by MrBafner, Mar 24, 2010.

  1. MrBafner

    MrBafner Member

    Joined:
    Aug 2009
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    Location:
    Australia
    On our shinohara 66IIP we every image has water streaks going through the entire image. They are very fine going in the same direction as the rollers, and not on every print. It was happening on bond and card.

    We replaced the superblue and printing on bond stock is now perfect.

    Printing on card we have the problem. The engineer says its something to do with the plate / chemicals ... we run Alcofree at a temperature around 8deg to 13deg C.

    Have tried different types of plate cleaners, gums, and different speeds.

    In fact when we speed the press up the water problem is worse. We have adjusted the % on the pod and still no good on the gloss card.

    We don't get this problem on bond or gloss paper. Any suggestions?
     
  2. turbotom1052

    turbotom1052 Senior Member

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    Location:
    Vermont
    my first suggestion would to be to keep cutting the water speed down till you just start to dry up. then increase water slowly till the dryup goes away. then you will know that your printing with minimum water. keep us posted!!!
     
  3. RichardK

    RichardK Senior Member

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    Location:
    Derby, UK
    Stop the press and check if there are corresponding streaks on your rubber dampener rollers.

    Check your forme and or metering roller are matt with a delicate 'nap' not smooth and shiny. If the latter then it's time to recover them.

    If the streaks run from grip to backedge then it's almost certainly worn or badly set dampeners (check roller nip widths are within manufacturer's guidelines...it wouldn't hurt to check your inkers either)

    The issue will show more on cmyk builds of dark solid areas in particular PMS 429 and reflexy blues. On absorbent stock like bond and offset the problem won't be as obvious as on coated art.
     

  4. MrBafner

    MrBafner Member

    Joined:
    Aug 2009
    Messages:
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    Location:
    Australia
    Yep, played around with the dampeners and it seemed to have fixed the problem.

    Thankyou for the help, mush appreciated. We will definately know this for future times.

    Cheers
     
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