[gbl08ma]

I know that when the color heads on my printers are obstructed, black text will often come washed out (as if you printed in economy mode, or worse). I have looked at black text, printed with my newer Epson, with a magnifying glass, and I can see a few color dots near the edges of the text (these are not photocopies, it's text documents printed in B&W mode). I suppose it works a bit like anti-aliasing in some font rendering systems.

I'm not sure how B&W inkjet printers solve it, but it's probably by spending more ink to avoid the wash-out. As other people pointed out, some color printers allow for printing with just the black cartridge in. I don't have one of these to compare, so it's possible the text doesn't look as crisp on these because of the lack of "anti-aliasing".

I suppose part of the reason for this limitation to apply to some printers but not others has to do with the business model (ink is expensive and for some brands/model lines it's the main source of revenue), and perhaps the technology used - some printers have disposable headers on the cartridges themselves, and others (like the printers I own) have non-disposable headers, which basically means the printer is ruined if ink dries up in the headers. This may be why some printers require the cartridges, even if empty, to be in, so the headers are not as exposed to the air.

Unfortunately manufacturers don't like to give extensive explanations (see my business model point above...), but on user forum threads like [0] and [1] there are some suggestions for why things are the way they are.

[0] http://www.tomshardware.co.uk/forum/224699-28-print-black-co... [1] http://superuser.com/questions/409473/how-to-print-in-black-...