I am creating print PDFs from InDesign that contain Illustrator files. Most of these Illustrator files have black outlines used. When you create a fresh outline with 100% black, it’s not set to overprint. And apparently Indesign doesn’t give it the overprint attribute either even if “Overprint Black at 100%” is checked, because it’s from an embedded file.
So, the print PDFs, in PDF/x-1a standard, have all the black strokes in knock-out mode when I check through the Output Preview.
Now, the only option left is for me to use the “overprint black” option from Edit Colours of Illustrator for hundreds of illustrations and then save and export fresh Indesign PDFs.
Shouldn’t black automatically be set to overprint in these software?
What do the pros do in such situations?
Black is a special swatch in InDesign. It can’t be deleted and it can be set to Overprint Black at 100%. Sadly, this is not the case in Illustrator, where Black is just the name of a swatch.
Note that only the specific swatch Black can be set to overprint. If you manually make a CMYK(0, 0, 0, 100) swatch, it will knock-out instead.
When the Illustrator files are placed in InDesign the black lines are not recognized as Black, but CMYK(0, 0, 0, 100).
Neither InDesign nor Illustrator should automatically overprint black in my opinion. What if you wanted the opposite? When placing object on top of each other in real life they normally cover each other (unless they are transparent). Setting black to overprint is a special technical “trick” for print.
Now that you’ve made this mistake, you are probably not going to make it in the future, but what to do now?
I see only two solutions:
Do what you’re doing: Open every single file and correct the error. It’s tedious, but he upside is that your files are fixed for good.
Use some kind of pdf editing software on the final pdf. I use Enfocus Pitstop Pro at work. It’s a plugin for Acrobat Pro which provides all sorts of editing capabilities. Maybe you have access to something similar?