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Overall red heavy on press

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  • Overall red heavy on press

    I am trouble shooting an issue our shop's been experiencing with for a while. Our onscreen color correction looks great, our color proofer looks fairly close, but when our 4-color jobs are run on the press they're coming out noticeably red heavy. The press operator has had some success when running the red at a lower density, but that's not a solution. I'm a bit stumped as to what my be causing this discrepency. Any tips or steps in the process that I should be checking/correcting would be very much appreciated.

  • #2
    Re: Overall red heavy on press

    It could be
    the colour magenta you use - ink manufacturers buy pigments all over the place
    the colour sequence - in relationship say to the blue - so you could try swapping sequence.
    In the UK we have real calcium issues with magenta which scales up the rollers - we descale them every week.
    Of course it could that your proofing is wrong - so if you could call back a job you have printed and see what that now looks like on the press.
    I am sure u have ckecked that the magenta isnt doubling - so I will rule that one out.
    Its unlikely to be your Magenta plate if you are using CTP - unless you have aspecial Magenta curve incorrectly applied.
    I would think you have checked damp, blankets and imnpressions - so I will rule those out

    The first thiing I would do is measure the 50% tint patch on the Magenta and Cyan and make sure they are what I expect them to be. THat easily rules the plate out/

    Next swop sequence - that will eliminate damp, blankets any,movement in the grippers which would cause doubling and any other mechanical issues with the press.

    If I still have the same problem then I may try a diffrent ink set or batch of ink (if I had one on site I may do this first)

    My last resort would be to call back a previous job and put is back on press

    Hope this helps



    • #3
      Re: Overall red heavy on press

      What type of press and plate output devices are we talking here?


      • #4
        Re: Overall red heavy on press

        This sounds like a problem with the monitor and proofer not simulating the press output, as Peter suggests above check mid tone patch, if it falls within reasonable tolerance then plate and unit are probably ok, Run a job up to standard weights, check TVI and trapping values if all ok and proof does not match re-calibrate proofer to match press output. I would be very suprised if the ink were the cause but without seeing printed sheet im guessing. Fingers crossed the red unit shows high TVi.


        • #5
          Re: Overall red heavy on press

          I have output to both our in-house CTP unit, Heidelberg Quicksetter 400 and had a second party output film that we've stripped and plated ourselves. Each job experiencing the color issue has been printed on our Heidelberg GTO 52.


          • #6
            Re: Overall red heavy on press

            If you have used three output devices and they give the same results then it suggests its the press espescially as earlier you said moniter and proof were ok. Is it a four colour GTO?


            • #7
              Re: Overall red heavy on press

              It is a 2 color press.


              • #8
                Re: Overall red heavy on press

                Seems like you need to finger print your press first, then use a color management workflow to line up with your proofer and press to one standard profile like SWOP or GraCOL. CGS have something call Press Matcher, it may help you to solve your color matching problem. Talk to them!


                • #9
                  Re: Overall red heavy on press

                  From what you say its must be the proofers , the ink or you have a doubling problem which you cant see .

                  Firstly I think we must ask how did you arrive at the colour of your proofs.

                  Was it from a press run or just a profile you were told to use.(remember that with a two colour you are printing wet on dry )

                  <<< You have checked your densitometer I AM SURE>>>

                  The second is what sequence are you printing

                  I am sorry that it goes on


                  It would be also good to know what your skies and fleshtones look like - its a good guide red skies and red faces may show us more


                  • #10
                    Re: Overall red heavy on press

                    Good morning, 2shoff \\\\Much good advice to this point, but let's start at the press (where color correction should start)
                    \\Measure a gray patch printed on press with your densitometer. Is it gray? (all 3 color components +/- 0.03 of eachother?) My guess is no. If that's the case, you'll need to get to the bottom of why on-press color is shifted. To do this:

                    1) Make sure your plates are giving you the percentage you're after. When you ask for 45%, is it 45%? If not, start there.
                    2) Next, determine how much gain there is on press. If you're not getting the output specified by your standard (Gracol or SWOP or whatever) then you'll have to make an adjustment in your platemaking front-end.
                    3) Now that your press is printing to whatever objective, independent color standard you have chosen, address your proofing system, if necessary.

                    You are printing to an industry standard, right?

                    Why color would change from "then" to now is a question of standards. Did you change ink? Is this job a different halftone frequency? Has someone been fudging your RIP? What kind of color management is embedded in the job? (And are you stripping it out?)

                    Good luck and let us know how it goes!



                    • #11
                      Re: Overall red heavy on press

                      what sequence do you print, and which colours print wet on wet,

                      Edited by: Paul Green on Jan 17, 2008 8:56 AM


                      • #12
                        Re: Overall red heavy on press

                        Ok, a two color press has an extra degree of dificulty.
                        You absolutely need to fingerprint that press.
                        You have to establish press curves to make your plates.
                        You must run your color to your "perfect' densities.
                        If you have the right dot-gain curves on your plate image and if the pressman runs to density then, your will have good product.
                        Trying to run your magenta/cyan press run onto a black/yellow first run will only get you into trouble if you are not using established curves and densities.


                        • #13
                          Re: Overall red heavy on press

                          all points so far a valid but if you have a standard already set (even if not fogra 39 or iso 12467 then re profiling may not be something you want to jump towards as repeat jobs may prove troublesome, i would print cyan first then magenta second, it might make things less red, then black and yellow. i know from experience its faster to print in different sequences but if your having colour issues its the only way forward. If your already trying this then you have no option but to chose a less pigmented Magenta e.g Stelin hostag or go down the TVI curve route. the second is the more sensible option but as earlier if you have customers happy with a product you supply with consistent results then your stuck between a rock and a hard place. I know form experience that some times its best to stick to what customers expect. they do pay our wages.


                          • #14
                            Re: Overall red heavy on press

                            Thanks everyone for your excellent input. In checking our calibration, it looks as though we've been having a really high amount of dot gain with the Magenta and Yellow.


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