Ink density and water level

Discussion in 'Ink' started by Printand, Jan 3, 2017.

  1. Printand

    Printand New Member

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    Jan 3, 2017
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    Greece
    Hi everyone,

    We have noticed that sometimes eventhough the densitometer reading is the same, the color gets darker. I have been investigating this for a little bit. I feel like this might have to do with water level. The other day, we changed our fountain solution as it got dirty during printing. With the fresh solution, we were using less water. We continued printing the same job and the color was very similar to what it was before the fountain solution change but the density reading was higher. Is there a correlation in between? Any help will be appreciated.

    Thanks.
     
  2. turbotom1052

    turbotom1052 Senior Member

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    over emulsified ink on a presses roller train will tend to print with MORE dot gain as the ink tends to loose tack, as it becomes water logged. If your dot gain is higher than it should be images will tend to look over inked while running the same density as read by your solid patches. This makes a good case for quality fountain solution and regular maintenance and replenishment of your solution as conductivity rises. I do not believe a mid week draining and flushing of the circulation system would be excessive. Are you monitoring your conductivity daily? If not you should!!! Swap that dirty solution out as needed to be able to print with minimum dampening. A good indicator would be to think about swapping it out when you find yourself running the dampener speed up higher than usual.
     
  3. Hman1956

    Hman1956 Member

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    Location:
    commack NY
    I disagree with changing the fountain solution weekly. we run 2 KBA 106's one UV and the other Con. inks. we are a folding carton printer running 24/6 we print high end Pharma/cosmetic work.
    when we see a rise of 1000 um ( that takes about 2-3 months) we change the flo-clear filters, turn off the feed and run the tank down. we have found the by changing the fount you go from one extreme to the other and so will you print characteristics. but by just running the tank down and letting it refill it will bring the conductivity back in like.

    just my take on it.

    Bill
     

  4. turbotom1052

    turbotom1052 Senior Member

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    Bill curious to know if you have auxiliary filtration above and beyond the filtration supplied with the press. There are high end systems out there that will do wonders for extending the life of the fountain solution. These systems come at high end price too. Also are you using an auto dump system?
    There also is the issue of paper!!! If your doing high end Pharma work then Ill bet you are fortunate enough to get a quality sheet to print on. Its often when your a commercial printer and printing on lots of crap that you see the sharp rises in conductivity. My reason for a weekly change of solution is so as to never get the conductivity through the roof. The recovery from a slightly high reading on a Friday night and the fresh batch startup conductivity on a Monday morning is not such a jump.
     
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