Does anyone know what would cause the following effect on a black and white printout? Scenario: color inkjet printer - wasn't used for almost 6 months - I ran built-in maintenance modes a half dozen times each - color printouts look just fine. These aren't actually printouts but copies, though printouts do the same thing.

Black ink cartridge bad or the head for the black ink is partially blocked?

Don't be so sure. Look at a color printout closely. See if the black ink in the color printout is actually behaving the same way.

This might be tough, because the point of a four-color additive printing process is that if you combine Cyan, Magenta, and Yellow at 100 percent strength, you get a color that is nearly black anyway, and the black ink is only there to reinforce it and make for richer dark shades.

Anyway, if you're sure that's not it, if you're sure the black ink head is behaving correctly for color prints, then check and see if there is some kind of a "paper" setting in the printer driver that controls the type of paper. If you put in glossy color-print paper, and select glossy paper in printer driver, that's a different way of applying the ink than plain paper printing black and white. Maybe it's just a setting in the printer driver.

And, of course, make sure you're not putting special one-sided paper into the printer upside down...

What brand printer is this anyway? Epsons are notorious for having their heads and ink feed tubes getting gummed up if you don't use them for a long period of time. Not fun or easy to fix though. HP integrates the mechanism into their cartridges so you just replace the cartridge.

Tony - I understand what you're saying, I was just saying the color printouts look just fine to indicate that the color cartridges don't have the same issue as far as I can tell. On the color printouts I made I looked and couldn't tell if the black was having issues.

Trevor - this is an HP, but it's a fairly old one where it doesn't appear that the heads are integrated into the cartridges. Sorry, I can't remember the model.

Thanks for the help folks. They're going to live with the current operation for now, as plain black text looks just fine. It's just when there's a field of black that it's noticeable.

AFAIK, HPs have always had the heads in the cartridges. Have you tried swapping out the black cartridge?