My experience with printing high quality black and white prints is to pick "greyscale" in the advanced print setup. The R210 will then use the black cartridge for the black plus a mixture of cartridges for the shades of grey. It will also show you which cartirdges it will use. A very nice touch!
I presume for a picture that is just hard black and white, the printer will only use the black cartidge. However, the R210 will attempt to reproduce as precise a print as it can, so any level of grey will bring the colour cartridges into play, just check in advanced settings. I hope that helps.