HP Deskjet 1050
I have just fitted my HP Deskjet 1050 with an external supply of ink. The ink goes into the HP original cartridges via 4 flexible tubes. To do this, I had to block the air holes found under the sticky label on top of the ink cartridge. After doing that, you must open the airhole in the 4 bottles of ink, which are stored neatly in a box.
This made me wonder, what forces the ink out of the cartridge and onto the paper?? Air I suppose?? How is it pumped into the cartridge??