How can I convert Pdf from RGB to CMYK, keeping font color 100% K while working in Illustrator?

When I try to open the document in Illustrator and I convert to CMYK the black text converts to rich black, but to set up for Offset printintg I need the text to be only in Black (100%K).

  • 2
    Can't you just select the type and reset it to 100k?
    – Scott
    Commented Apr 10, 2015 at 16:46
  • What is on the pdf? Text only?
    – Fannie
    Commented Apr 10, 2015 at 17:19
  • why don't you replace re rich black swatch the the black K 100% ?
    – hsawires
    Commented Apr 10, 2015 at 17:30

3 Answers 3


If you have Acrobat Pro, you can run a Fix-up on the pdf to convert the color space to CMYK.

When you set-up your Fix-up there is a checkbox to Preserve Black Objects that will convert black text to 100%K.

  1. open up a RGB .pdf you want to convert
  2. File > Document Color Mode > CMYK converts your RGB pallete to CMYK
  3. Swatches pannel > Add Used Colors adds every color swatch your document uses Add Used Colors
  4. file swatches used in document are now present in your swatches panel Used Color Added to swatch panel

  5. select the color swatch you want to convert to 100%K, be sure to set 'Global' checkbox active this makes the color change in the entire document enter image description here

* color shifts occur
** from time to time swatches from inside of groups or compound paths aren't added properly, so make sure to ungroup everything before you add/modify swatches
*** your document may have a variety of rgb blacks, so it will output a variety of cmyk blacks during rgb>cmyk conversion, in this case you have to make sure every black is 100%K black. if you have several black swatches to convert to 100%K, name conflicts might occur, so you should assign a different name in each case*

**** you may have to double check that every black is 100%K, just hit Add Used Colors a couple times until zero swatches are added to your pallete. if you change newly added swatches to 100%K and they continue to add, this means some swatch is assigned to an element inside of group or compound path, which prevents you from globally affecting it


For those without Acrobat Pro: I wrote an Illustrator script for this purpose:

Flatten Black.jsx
Flatten Black.jsx Demo

See my answer on a similar question: How to batch convert RGB to CMYK and have black mapped to 0%C, 0%M, 0%Y, 100%K (NOT rich black!)

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