How to convert CMYK in a PDF to black and retain the spot color

[DW Eppler]

I have a 600 page PDF that contains CMYK text and line art and a spot color for some of the text. I need to convert all the CMYK text and line art to 100% black, while keeping the spot color. How can I do that (preferably in Acrobat Pro)? (The job was done in InDesign.)

[Luke Jennings3]

In your sample page, the black text is 100% black and the red text is 100% PMS 220U. The crop marks however are registration (100% of all used colors). Some digital printers charge per color, so I'm assuming you want to change the crop marks to 100% black. You can easily do this with a preflight profile (Tools> Print production> Preflight> Fixups). If there are other 4C black elements in your document, you can use another preflight profile to map the specific color to black only. If you don't need the crop marks, you can place the PDF into InDesign using the place multipage PDF script and export to a new PDF without crop marks. 

Here is a link to a related topic:

https://community.adobe.com/t5/acrobat-discussions/how-to-convert-color-image-to-black-in-acrobat-dc...

[DW Eppler]

Thank you, Luke! That was very helpful!

However, your report that the black text is, in fact, 100% Black has prompted another question: How can I tell that it's 100% Black?

I used Output Preview, with Output Intent: U.S. Web Coated (SWOP) v2, since that's what the PDF was created with), and Simulate Overprinting checked. With Preview set at Separations, 5 colors are listed--CMYK + the spot color (see CMYK + Spot.png). If I turn off the spot color and black, the text still appears as CMY (see CMY only.png.) Not until I turn off the C, M, & Y does the text disappear. I assumed that meant the "black" text was actually CMYK.

What settings do I need in Output Preview to confirm that the black text is 100% Black, with no other colors? Or do I need to go somewhere else in the Acrobat menu to find this information?

I have several "red-letter edition" jobs like this, which need to contain only black + the spot color (so we don't get charged for 5 sets of plates!), so learning how to do this is quite important to me.

Thank you for your help.

[Luke Jennings3]

That's odd. I'm using the same settings in Output Preview, but the type is clearly black only here. I assume your version of Acrobat is up to date. Do you have another PDF with black only text you can check using Output Preview? You may need to reset your Acrobat preferences, if no one else has any better suggestions.