OM2 said:
pigment? dye? what's the difference!
My understanding is that pigment ink tends to have better longevity than dye ink. If you are a pro selling photos to people who expect the pictures to be fade resistant, you should use pigment ink.
I believe that dye ink tends to be more colorful and vivid. It tends to resist print-head clogs better than dye ink, which makes it much easier to work with. If you print a lot, with few days between print sessions, then my reading indicates you might be ok with pigment. Otherwise, dye ink will have far fewer clog problems.
My impression is that a natural progression is to start with a dye based printer, and if you get to the point of printing a lot, and wanting/needing archival longevity, you eventually get a pigment based printer. I believe the latest Epson printers like the 3880 have coated nozzles so clogging is less of an issue.
sorry for my ignorance
(i'm a refill master wannabe - just started - just about to refill my first ink cartridge for my mp640!!)
We all were at first. Refilling is pretty intimidating when starting. With a great resource like nifty-stuff, I tend to be the opposite of the A. Lincoln quote:
"Better to remain silent and be thought a fool than to speak out and remove all doubt."
I think it is foolish to not ask questions, especially at first when everyone understands you are a newbie. However, I know I have been guilty of asking questions out of laziness when I could have done my own research with Google, or better, searching on nifty-stuff.
The mp640 looks like a nice, fairly modern all-in-one. I'm not that familiar with the 221 dye carts it uses. I believe there is a resetter for it. I believe I read somewhere that the ink capacity is less than the BCI-6 and CLI-8 carts, which would be a liability if you do quite a bit of printing.
I'd suggest updating your profile to show what printer you have, and where you are located.