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CMYK Printing - Dot Gain/Curves

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  • CMYK Printing - Dot Gain/Curves

    Hi,



    I am fairly new to the printing industry. As the graphic artist at my company, I have to be familiar with pre-press techniques. We have been having some issues with printing CMYK.

    I need to go in and adjust dot gain percentages.



    Does anyone have any information on how to go about doing this?



    Thanks!

  • #2
    Re: CMYK Printing - Dot Gain/Curves

    Why do you think you need to make dot gain adjustments and in which application(s) do you intend to make those adjustments?

    best, gordo

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    • #3
      Re: CMYK Printing - Dot Gain/Curves

      I think first of all u need to say what issues you have ?

      "in the world" we have three real standards -

      what is known as ISO (which a lot think of as European) 50% on plate = 64% and

      then there is G7 (US version) 50% = about 68%)

      ink densities on coated papers are about the same K 1.7 C and M 1.4 and Y 1

      and finally yours the printer .

      With ISO we tend to proof to ISO and then match the proof on press

      With G7 (I will let a G& expert tell u what they do)

      With your standard - you most likely match the proof to your presses and the clients complain.

      so we need to know what is the problem
      Peter

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      • #4
        Re: CMYK Printing - Dot Gain/Curves

        If you need to set up DOT gain at your company to be applied to your plates what you need to do is first get the INK and Press companies involved to find out what the optimum ink densities or LAB values should be for each ink as well as getting the presses set back to an optimum playing feild.
        Also get the press manufacturer to tell you what the optimum dot gain should be for your presses, they will probably also help you set it up(heidelberg did with our presses).
        Then you should run a Linear set of plates using a calibration test form from your press supplier on a quality stock to the settings supplied by the ink manufacturer and get a reading of what your current dot gain values are. Then depending on the workflow software you are using you will need to enter in the current dot percentages from the linear test as well as the target values that you should be getting when a job is printed and that will create a curve that is to be applied to your plates.
        What you don't want to do is apply the curve to the raw or ripped files as you should always leave these as supplied to you.
        1 important thing to keep in mind when running this test is you need to make sure that you have good clean neutrals when printing the linear plates as this is a good veiwng point of how well the colours are trapping and that the INK densities or LAB values are correct. When you re doing the same calibration test after you apply the DOT gain curve to the plates make sure that the neutrals are still a neutral colour and that there is NO shift in colour, if there is make sure the densities or LAB values are correct and if they are you might have to adjust 1 or more of the dot gain curves to correct this problem.
        As you can see this is a long process and should involve all possible parties to help in this process. At aour company we do DOT gain recalibration or checks on our presses every 2 years and we treat it as a HIGH QUALITY job and spend all the time possible in getting it right.

        Hope this helps you in undersatanding what it takes to create a dot gain curve. It will probably be a struggle to get the printers at your company involved but it is a benefit to the compant in the long run.
        Aslo if you can what you want to do is see if you can put in a ICC calibration strip that your Proofing device suplier can use to create an ICC press profile to apply this to your proofers to help get them to match more accurately to the press so you can supply the client and the print room with a more accurate proof making every one happy and your life easier.

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        • #5
          Re: CMYK Printing - Dot Gain/Curves

          In Photoshop, you "Convert To Profile" under "Edit". You need to have the correct color settings in place for what you want to convert to (per your paper and press). I know that when we convert from RGB to CMYK for Web Uncoated, the difference is dramatic, AND it looks more like it will print. Also, Total Ink Coverage should be addressed.... if this is too high for the press/paper, the end product will look muddy.

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