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  • implementing G7

    Hi all....

    i need information Before implementing G7 in flexo presses, what are the steps involved?
    any one to known solution please reply...

    thank
    Edited by: ananth on Feb 19, 2008 9:04 AM

    Edited by: ananth on Feb 19, 2008 9:18 AM

  • #2
    Re: implementing G7

    Hi,

    Here the steps that most of our flexo users adhere to:

    1. Get a spectrodensitometer if you do not have one already.

    2. Establish the press curves grey balance of all your presses using the appropriate software. You wish to get the same results on all your presses. See PerfX Press Curves at http://www.podintegration.com/POD%20...%20Curves.html

    3. Get a professional Profiling Software. See PerfX Color Management Pro at http://www.podintegration.com/POD%20...rfX%20Pro.html

    3. Profile each of the presses

    4. Profile each of the proofers

    Your wish to have your proofer to match your presses to reduce or eliminate re-runs due to different color perception. Using numerical values your final product should match exactly the proof approved by your client.

    5. Apply the profile to your files, or place your profiles on your rip.

    or use hot folder automation to apply profiles to your incoming jobs. See http://www.podintegration.com/POD%20...%20Server.html


    Mimimum and maximum dot can be set to both press curves and ICC profiles. You will still have to do some correction on the files to cover special cases, but normally you should be able to get excellent results.

    Comment


    • #3
      Re: implementing G7

      The approach to the methodology itself can be common to other processes, but the intricacies of flexography and the variables involved (plates, sticky-back, anilox, ink viscosity, impression, ect) are what make this a challenge. Also, given that you don't arbitrarily adjust density, you will likely be more reliant on plate curves to acheive gray balance. Therefore, it is very important that an average response of the pressrun be used for curve creation...not just one sample (this is true for other printing processes, but I think more so for flexo).

      Maybe everyone's favorite flexographer Bill Whitfield is out their and can comment?

      Comment


      • #4
        Re: implementing G7

        Greetings,

        Favorite flexographer, interesting title. Michael is correct in stating that there are many variables that need to be considered when doing press tests of any nature, especially using the G7 methodology. A gentleman I know that does press optimization for a major flexographic plate manufacturer once told me that he stop counting when he got to 70 different variables.

        That said, my advice is that you invite to the press runs all vendors that cover the print process, including prepress, that you are not knowledgeable about. You will also need to contact your ink company and discuss their familiarity with G7. I have worked with 4 popular flexo ink companies and none were aware of G7 until I mentioned it.

        I think the G7 methodology has been very helpful and I would recommend the purchase of IDEALink to help determine the curves. I have also found that averaging press runs is a must to smooth out the curves that I see from my press runs. This averaging can be done by measuring multiple sheets or by the use of averaging software. If you decide to do it by measuring make sure you have a target and a measuring device that will not force you to measure in spot mode. Life is just too short for that. The number of sheets to average is open to debate and I feel can only be discovered after a few press runs.

        One of my most challenging tasks, much to my surprise, has been to get presses to run evenly across the web in reference to density (Lab values) and TVI. Press operators seem not to be instructed as a QC check to be concerned about evenness across the web, even though we in prepress have been placing QC graphic elements on both sides of the web for many, many years.

        Be sure to take very thorough notes as the G7 methodology takes a few press runs to get final results and you want to make sure all press components, the ones that Michael noted, are the same from run to run. Good luck, it can be done!!

        -Bill-

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        • #5
          Re: implementing G7

          Gentlemen,

          You are absolutely right about the fact that there are a lot of variables in flexo printing.

          This being said, my intention was to give some quick guidelines in reply to a post that was quite generic.

          Our profiler allows to average 4 samples on each device. Also Press Curves can be adjusted according to grey balance. You can have a look at this software at: http://www.podintegration.com/POD%20...%20Curves.html

          However as color management seems to be more a concern than before, I find it refreshing to have good exchange of thoughts on this matter.

          Cheers

          Comment

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