5 Replies Latest reply on Sep 22, 2015 4:04 AM by RuthK

    OPM1 / Overprinting

    RuthK Level 1

      Not sure if this is the correct forum.


      I use InDesign and send files to printers several times a week and rarely have any problems. Recently I received a printed item back from the printer. There was black text (100%K) on a yellow background (50%Y) and the text has knocked out the yellow background a bit so it has a bit of a white outline. I have never had this before.


      When I raised this with the printer they said that the text was set to overprint and therefore it didn't print correctly. And I should turn overprint off and resupply. They sent me a screenshot with Enfocus Inspector with the Overprint Mode set to Illustrator OMP1.


      I have sent the same file with the same PDF settings to the same printer multiple times without issue, and I don't ever remember having to change the overprint settings manually.


      Just looking for advice really, whether I can challenge this, and how to avoid this problem in the future.


      Thanks in advance!


        • 1. Re: OPM1 / Overprinting
          Peter Spier Most Valuable Participant (Moderator)

          The printer told you turn overprint OFF for black type? Run.


          Lots of poorly trained prepress techs have their RIPs set to ignore overprints by default, and the knockout could only have happened if the applied overprint was ignored.

          • 2. Re: OPM1 / Overprinting
            Willi Adelberger Most Valuable Participant

            Peter is right. InDesign overprints Black by default. If you want to avoid overprinting black you have to create your own black swatch. But normal text is always overprinted if black, only huge sizes are knocked out.

            • 3. Re: OPM1 / Overprinting
              G. Singelmann Level 3

              FWIW: The Illustrator overprint mode controls if  process colours can overprint or not. If it is set to 0 overprinting only happens with spot colours.

              In other words: Black text over yellow background needs the OPM set to 1.

              Which it is by default when you export from indesign.


              Overprinting is not the same as "mutliply". Meaning: If your text as a yellow value of anything but 0, that value will be used, which can also result in trapping problems.

              Therefore another explanation for your print result would be some colour management gone wrong, i.e. they somehow converted your pure black to a black with some value in the yellow channel.


              The recommendation to turn overprint OFF is quite mad though.

              • 4. Re: OPM1 / Overprinting
                RuthK Level 1

                Thank you everyone.


                So in short my file was supplied correctly. I thought this was the case but I didn't want to be too arrogant and wanted to check. I checked the file supplied and I had definitely supplied the text as 100K


                Let's hope they refund or reprint my job.



                • 5. Re: OPM1 / Overprinting
                  RuthK Level 1

                  Just to update you - the printers have absolutely insisted that I must turn overprint off in order to have my file correctly reprinted (!!??) and also suggesting an alternative that I set my 8pt, script black text to rich black (again, !!??)

                  I don't understand it as they've printed so many jobs correctly before.


                  They are absolutely convinced I'm wrong and I don't know how to persuade them, but I'm guessing someone in the studio somehow turned overprint OFF and therefore a slight misregistration has caused a white outline.


                  So annoying!