Illustrator colour models

[Adrian]

Hi!

We have just sent a specimen of a job we're working on to the printer as PDF files, and there seems to be a problem. It's a two-colour job, with mono (line or greyscale) illustrations. The printer is saying that (some of) the illustrations are CMYK and that this is a problem. We have looked at one of the illustrations in Illustrator CS2, and the colour mode is indeed CMYK. But it has only two options: CMYK and RGB. If we convert the eps illustration to greyscale in Illustrator, the converted illustration still has the CMYK colour mode. Common sense tells me (I'm not an Illustrator expert!) that it must be OK for the illustration to be in CMYK colour mode and be grayscale, and that it should therefore print in black only. Is the printer (who is in Spain, and with whom we are not in direct contact!) reacting to a "label" of some sort in the eps illustration file, or is there something more sinister going on here?

Best wishes, Adrian