Metallic ink with DOP plates

Discussion in '4-Color Offset Presses +' started by wiscowi, Jul 25, 2022.

  1. wiscowi

    wiscowi Member

    Joined:
    Jun 2019
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    Location:
    wisconsin
    I was wondering if anyone knows the trick to printing metallics with DOP plates. We had this problem with our Heidelberg QM's and now when I just ran this 2 color job on our Hamada b452a we had the same issue. The issue is the metallic ink creates a ghost image of what the other color is printing and sensitizes the non metallic plate. So when I just ran this gold and black job the black would slowly sensitize and start printing with the metallic, and even after cleaning the plate with conditioner it will still come back after a couple hundred sheets. I've tried increasing the fountain solution, running extremely wet, and adding adding alcohol but nothing seems to work. We've never had this issue back when we used to run poly plates and no one here really has any ideas of what else to try so I thought I would ask here, TYIA.
     
  2. NotAGooner

    NotAGooner Senior Member

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    Location:
    UK
    Don't know anything about Hamadas and I know metallics should go down first but have you tried switching units?
     
  3. wiscowi

    wiscowi Member

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    Jun 2019
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    13
    Location:
    wisconsin
    My first set up had the metallic and black switched between the 2 units but I felt like the black was slowly contaminating the gold because after about 400 sheets the gold wasn't the same hue anymore. The press shares a common impression cylinder between units 1&2 and 3&4, I'm guessing next time I'll have to try maybe putting black in 3 and the gloss varnish in 4 and leave gold all on its own.
     

  4. Jack liston

    Jack liston Senior Member

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    Sep 2019
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    Location:
    Connecticut
    Good idea you should have better results.
     
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