Give this web site a try, they have some good information
its for Cannon
I refill my Epson cartridges and the last time the printer started messing up I loaded both sides with an empty cartridge loaded with water and ran the clean utility. The key here, is that the ink is water soluble. My Epson 400 Stylus might have a few more years left in it.
As for a supplier, I use $3 for a b&w and $4 for a color cartridge isn't bad, and they are fast on delivery.
I have had the best sucess with refilling a cartridge one time only. Twice seems to be asking for trouble. So not only do I buy cheap cartridges, I refill them--I'm just saving some money so the wife can go out and spend it, go figure
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FYI: For those of you with an HP printer, the cartridge and print head are an all in one unit. Whereas the Epson they are separate