process Density and Dot gain questions

Discussion in '4-Color Offset Presses +' started by verbena, Apr 22, 2007.

  1. discountprintingservice

    discountprintingservice Senior Member

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    Oh, one other benefit I remember at that time was to reduce ink consumption & cost as black usually cost less per pound vs. cyan, magenta & yellow
     
  2. DanRemaley

    DanRemaley Member

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    The biggest advantage is the limit of color variation on press, since the size of the y-m-c dots are decreased, they vary less on press. ALL color copiers use GCR in their workflow.
    Yes, the 'common' blanket is a challenge, more because of contamination of colors, GCR will help as you said. I have a X-rite 530 for $1800 if anyone needs one.
     
  3. DanRemaley

    DanRemaley Member

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    The CORRECT sequence for process color work is K-C-M-Y, years ago when there were TURE research facilities like GATF an PIRA, they tried EVERY sequence and found that this is the best for the overprint colors of Red/Green/Blue. I don't make the rules - I just follow them!
    Dan
     
  4. maxpower

    maxpower New Member

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    The only way to know your correct densitys is to print to a standard, like iso 12647-2, they have a specified lab colour value for each colour, so it can change quite a bit with different machines and inks, once you get that, then you calibrate the plates to get the correct dot gain, in the case of iso 12647 its the same for MYK and higher for black, have a read of this document and you will get the idea mediastandard_2006.pdf
     
  5. DanRemaley

    DanRemaley Member

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    Good discussion- I just posted in the 4-color forum about grey balance printing.
    Study’s were made at PIRA (England)
    Best color sequence is C-M-Y (K can be first or last).
    The reason? M/Y gives excellent ‘reds’
    C/Y would yield excellent ‘greens’ BUT poorer ‘reds’ - humans are more sensitive to Reds!
    The grey balance is achieved at standard densities with dot gains at or near K-22 C-20 M-20 Y-18.
    As a “formula” C/M are the same Y is 2 less! (ie- C/M 18 Y-16 - lighter - C/M 22 Y-20 - darker).
    Free consulting (I’m retired)!
    danremaley@comcast.net
    412.889.7643
     
  6. DanRemaley

    DanRemaley Member

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    Here’s my take-
    All of the ‘color decisions’ are made prior to press! Pre press separates the image and decides grey balance & dot gain. Photoshop separations have 20% midtown gain.
    You will have to check with pre-press and work with them to develop plate curves for your press.
    The “secret” to printing 4-color is controlling grey balance at the correct gain - we do that with plate curves and density/dot gain measurements. The press can only print what’s on the plate!
    No dots, too big or small dots are a problem! Ha and we ‘blame the pressman!!
     
  7. DanRemaley

    DanRemaley Member

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    I found this old poster that has some information (attached). I also have all the dot area values for the entire tone scale - call me if you like 412.889.7643
     

    Attached Files:

  8. DanRemaley

    DanRemaley Member

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    Here is a quick and easy way to print to Grey balance at press (you'll need help from pre-press though). You can change the "wanted" numbers for midtown gain but this will be a great starting point. Let me know . . . Oh - and the uncoated is beautiful!!
     

    Attached Files:

  9. Sid Wilkins

    Sid Wilkins Member

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    Density or reflective density should be in the range of 0.00 and 3.00 points for printing applications.
     
  10. DanRemaley

    DanRemaley Member

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    Density is usually measured "absolute" (including paper) and in the U.S. - Status 'T'. Run sequence is K-C-M-Y (Black can be first or last) - Reason is that the "color" of the 'RED' trap color is better with M-Y. "GREEN" trap is better with C-Y but "RED" is much worse and we are more sensitive to Reg than Green. I have an excellent book that explains this but you will have to contact me off line- danremaley@comcast.net
     

  11. DanRemaley

    DanRemaley Member

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    Attached is a way to print to grey balance at press. Measurements are Status 'T" and absolute (including paper). Call with questions:412.889.7643.
    You'll need help from pre-press and a rip that has 4-channels Y-M-C-K to enter the supplied "wanted" values.
     

    Attached Files:

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