Refilling ink cartridges is false economy. The HP cartridges have the print head built in, and the head is only designed for a certain life span, thus you're putting ink in a cartridge with a worn out head, which is like trying to put racing fuel in an engine with leaky valves and piston rings; it ain't gonna help. Also, most printer manufacturers formulate their own inks to match their papers, and refilling ink cartridges with unknown ink can lead to very erratic printing results, especially if you're dealing with graphics and photo printing, where quality is important.