After about a year of using the 7800, I've been suspecting that there is a lot of ink remaining in the 220ml cartridges after they are declared to be "ink out" by the machine. I've measured about 25 ml left on all cartridges except the Light Black, which likes to leave 45ml. It seems to me this is quite excessive. Epson tech support told me up to 20% "is possible."
Is this typical? If so, it strikes me as pretty egregious design flaw. I know there has to be a little ink left to prevent air getting in the lines, but this much?
I wonder how HP and Canon handles this?