Prevent a B&W document from separating to CMYK

If your B&W document separates to CMYK, then there must be color in there somewhere. Perhaps you're using a "rich" black (with CMYK values) or the Registration swatch instead of the Black swatch. Or maybe there are phantom (hidden) color objects.

To find and remove unwanted color:

1. Choose Select All Unused in the Swatches palette pop-up menu.
2. Click the Delete Swatch button . If any swatches other than None, Paper, Black, and Registration remain in your Swatches palette, you know there's color somewhere in your document.
3. Drag unwanted color swatches to the Delete Swatch button. If the color is being used, the Delete Swatch dialog box displays.
4. Choose Black from the Defined Swatch menu, and then click OK.

InDesign will remove the swatch and apply Black to any objects that were using it. Scan your documents for these objects (make sure all the layers are showing), and then delete them.

Additionally, you can confirm color usage in your document prior to exporting it to PDF by using the Preflight command. And it's also a good idea to ask your print vendor for their B&W printer profile. Install this file on your computer (in a location specified by your operating system) and you'll be able to select it from the Destination menu on the Output panel in the Export Adobe PDF dialog box, or from within the Print dialog box if you choose to print to PostScript and then distill the file.