Density Values changed when substrate is dry

Discussion in '4-Color Offset Presses +' started by assman, Jul 19, 2007.

  1. assman

    assman New Member

    Joined:
    Feb 2007
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    Hi,
    I recorded all density values at C=1.40 M=1.40 Y=1.30 K=1.80. These are the values I used when Art Card is being printed. However, the values changed drastically when the substrate is in dry condition and obviously the colour vary from the first piece. How do I rectify and control the wet and dry issue? Thanks in advance.
     
  2. Stu

    Stu Member

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    Dec 2006
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    get a densitometer with a polarising filter
     
  3. mrheidelberg

    mrheidelberg Senior Member

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    Jan 2008
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    Location:
    United Kingdom
    Hi,

    Obviously some substrates vary as to how much ink they soak up so allowances can and sometimes have to be made. A good surfaced art paper generally won't change that much.

    Regards.
     

  4. turbotom1052

    turbotom1052 Senior Member

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    Location:
    Vermont
    There is nothing shy of on press testing, under your companies specific conditions, that will allow you to get an ACCURATE handle of what is commonly referred to in the industry as "dry back". Its well known that a high gloss art paper will offer the least amount of dry back, with a very porous uncoated sheet offering the most. This is why my suggestion would be to test various stocks with the inks your company regularly uses, under the same repeatable conditions. Record the density readings you get on all colors just as the sheet is coming out of the presses delivery. Check them same readings the next day, after the sheet has fully dried and record the readings. The difference between the 2 readings would be what you could reasonably expect when printing the tested inks, on the tested paper, on the tested press, on the testing day.
     
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