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Trouble color matching blues & purples - offset CMYK, G7 methodology, GRACoL 2013

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  • #16
    Originally posted by gordo View Post

    I don’t agree. The first thing to do is establish your manufacturing’s current condition relative to your defined targets. That will help narrow down what you should try.
    Otherwise you’re like a drowning person flapping their arms uselessly thinking that at least they’re trying something.
    Also known as 'grasping at straws'. Knowing what you're dealing with is the first step towards a successful solution.

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    • #17
      Prepress lables,

      In what way do the blues/purples on the proofs differ from the offset printing? (lacking cyan, lacking magenta, weaker/stronger in proofs, or what)
      What rip are you using to color manage the proofer?

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      • #18
        The purple colors are made from midtown (40-50-60%) areas of Mag/Cyan, they are the most difficult to control because of dot gain.
        i would measure the mid tone gain of your “good” profile sheets & compare the gain of your current sheets. You will have to add a color bar that contains Solid&50% patches of each color. I would also add a grey patch too (50C-40M-40Y). Felix Brunner has it right saying 70% of color shifts are because of dot gain - only 10% caused by SID”.
        So what do we measure?
        Call with any questions 412.889.7643

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        • #19
          If you are working with Gracol2013, I recommend contacting Idealliance or a G7 expert and have them walk you through this.
          "Tinkering" with your proofing is a nono and same goes for playing with your ink densities on press.
          Is you customer using the correct icc profile and are his or her proofs color correct for the destination/production paper (certified to a corresponding standard)?
          You yourself should first of all be proofing to Gracol2013, corresponding to the paper you are about to print on, so you know your target colors, otherwise you might as well switch off the lights before you start printing. The icc profile used by your customer needs to be correspond to your output curves, adjusted for output according to Gracol 2013 - and then there is the press of course.

          Do you know if your standard densities are correct - M1 LAB values once dry, according to the current ISO 12647 standard?

          Best regards

          Ingi

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          • #20
            Is this problem solved?
            If not, we will need you to answer the questions that have been asked by everyone.

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            • #21
              Gentlemen,

              Some information I hope of interest and value.


              Regards, Alois.

              Bright Magenta Page 1 043.jpg
              Bright Magenta Page 2044.jpg








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              • #22
                Originally posted by roger View Post
                Is this problem solved?
                If not, we will need you to answer the questions that have been asked by everyone.
                prepress labels
                You are so bad!

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                • #23
                  We did redo the press curve after I posted this thread--sorry for the delayed response. We've been running to a standard set of ink densities, and having a better time than before. We'll keep an eye on it.

                  Gordo, if you're still reading this--would the Curve4 software we're using for curves give you all the info you're requesting?

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                  • #24
                    Originally posted by prepress labels View Post
                    We did redo the press curve after I posted this thread--sorry for the delayed response. We've been running to a standard set of ink densities, and having a better time than before. We'll keep an eye on it.

                    Gordo, if you're still reading this--would the Curve4 software we're using for curves give you all the info you're requesting?
                    Not really. This is what I asked for:
                    what are your SIDs measured dry?
                    what are your solid ink Lab values measured dry
                    what are your RGB % trap values?
                    what are your RGB trap Lab values?
                    have you plotted/charted your dot gains? If so can you share?
                    (I'll add - what are your dot gains in 10% increments for each color when printed with uncurved plates?)
                    are you using the same instrument to measure in prepress and pressroom?

                    Ideally you'd also have taken photo micrographs of the halftone dots and also confirmed that they are consistent across the sheet.

                    A doctor doesn't recommend medication before doing a check on your current health status. Symptoms are noted, however, they may not determine the course of medical care. In like fashion, before applying "fixes" to the press, IMHO, it's prudent to do an audit of its current condition. That can help identify where the problem actually lies and suggest a solution.

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                    • #25
                      Originally posted by DeltaE View Post

                      prepress labels
                      You are so bad!
                      LOL. My original question to Prepress labels is in regards to differences between GRACoL 2006 and 2013. In my opinion, the differences in cyan + magenta in blues are huge and his using 2013 as the proofer target could be the sole cause of his proof to press problem.

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                      • #26
                        Maybe I misread somewhere, but let me ask you this...
                        Is your designer set in SWOP v2 or GRACoL 2013 in their design apps?
                        Is you offset press trying to match SWOP v2 (or other than GRACoL 2013)?

                        If your file is built with CMYK images in a software whose color space is SWOP then unless those images are tagged they'll come in to your epson and hello there welcome to gracol! At that point your colour has most likely visibly changed. The color spaces from design to proofer to press must match if any sanity is to be had.

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