6 Replies Latest reply on Jul 30, 2016 11:37 AM by SimonLinden

    Two different blacks in PDF-file

    SimonLinden Level 1

      I have designed a book with two colors: black and PMS 369C. I sent it to the printer just before going on holiday expecting no problems with it. But they returned to me saying that it has two definitions of black and they can't print it as two colors. They couldn't give me any more information than that however.

       

      The book is made in indesign and has some vector images drawn in Illustrator. To get more nuances of the PMS color I mixed it with both white and black, I believe it's called overprint when mixing with black and I've only done that once before so it's quite possible that it is the cause of the problem. I must admit I have little understanding of color profiles but I think it's possible that the black I used in the Illustrator files is defined differently than the basic [black] swatch I used in InDesign. What is the correct way to define black for these kind of print jobs? And more importantly is there a simple way to remove one of the blacks in the PDF file and replace it with the other?

       

      I'm attaching a screenshot from Acrobats output preview that might help.

      overprint-issue-1.png

      The output preview reveals that there is one spot color black, but the process black is also used on other instances. Does it matter which one I use as long as I just use one of these blacks? Since I'm not using CMYK it seems counterintuitive to use 0,0,0,100 for black, but maybe it's alright?

      I don't understand the ink manager but I saw that I can replace a spot color with an ink alias. If I set it to process black would it solve the problem? If it's that easy I don't understand why the printer would bother telling me to fix it rather than just doing it themselves?

       

      But I suppose it isn't that easy. I should be able to fix it by editing each illustration in illustrator, it seems like deleting the K=100 swatch will revert any instance of that color back to 0,0,0, plus whatever tint percentage of K=100 was used. But there's probably a better way, either by fixing it directly in Acrobat or upon exporting from InDesign. Any suggestions?

        • 1. Re: Two different blacks in PDF-file
          Peter Spier Most Valuable Participant (Moderator)

          Use only one black, and the process black is OK.

          1 person found this helpful
          • 2. Re: Two different blacks in PDF-file
            SimonLinden Level 1

            Thanks. And using ink manager to replace the black spot color with process black will solve it? I found that this could be done when exporting from indesign as well. I looks alright in the output preview, only one black there now. So I'll send them the files and see if its ok.

            • 3. Re: Two different blacks in PDF-file
              Peter Spier Most Valuable Participant (Moderator)

              Should be fine.

              • 4. Re: Two different blacks in PDF-file
                rob day Adobe Community Professional & MVP

                I don't understand the ink manager but I saw that I can replace a spot color with an ink alias. If I set it to process black would it solve the problem? If it's that easy I don't understand why the printer would bother telling me to fix it rather than just doing it themselves?

                It is easy to alias you K=100 spot color to process black, but I can understand why your printer doesn't want to take the responsibility especially when you are using overprints to mix colors. To Alias or force the K=100 to Process black:

                 

                Screen Shot 2016-07-30 at 12.42.38 PM.png

                 

                You could also use your K=100 spot as the black and use preflight to find all instances of process black and change them. Here I have a rule that doesn't allow any process color with a maximum of 2 spot colors. When I choose that rule as the preflight profile it flags one error where I have a rectangle filled with process [Black]—the other black rectangle is spot:

                 

                Screen Shot 2016-07-30 at 12.41.56 PM.png

                 

                To get more nuances of the PMS color I mixed it with both white and black,

                You have to be careful with using overprinting for spot color effects—some printers won't allow custom overprints. InDesign has a Mixed Ink feature that lets you build swatches with mixes of spot colors. Mixed colors are not color managed so the results can be unreliable—you wouldn't ant the design to depend on color subtly.

                1 person found this helpful
                • 5. Re: Two different blacks in PDF-file
                  rob day Adobe Community Professional & MVP

                  I found that this could be done when exporting from indesign as well. I looks alright in the output preview

                  Double-check your overprint colors in AcrobatPro and let your printer know they shouldn't override them.

                  1 person found this helpful
                  • 6. Re: Two different blacks in PDF-file
                    SimonLinden Level 1

                    Thanks for the detailed answers. I'll use the ink manager since it's quicker but good to know about the preflight option as well. About overprint - I appreciate the warning. there's always more to learn.