The HP DeskJet F4100 printer uses the HP #21 black ink cartridge and the HP #22 tricolour ink cartridge. After you have refilled the cartridges, you will want to reset the ink levels. The printer will continue to alert you that the ink cartridge is out of ink if you do not reset the levels. You can trick the printer into thinking that you have inserted a new ink cartridge instead of the same cartridge.
Flip the ink cartridge over so that you can see the bottom copper contacts. Do not touch these contacts with your fingers. Make sure that the contacts are towards the bottom of the cartridge when the ink cartridge is facing you.
Use scissors to cut two pieces of tape that size of one of the copper contacts.
Place the first piece of tape on the last contact in the second row from the left on the black or colour ink cartridge. It will be the seventh contact.
Place the ink cartridge in the printer. The printer will perform an alignment. When the alignment is done, remove the cartridge and flip it over again with the contacts at the bottom facing you.
Place the second piece of tape over the top contact in the second row from the right. It will be the sixth contact for the black ink cartridge. For the colour ink cartridge, place the piece of tape over the top contact in the last row on the right, which is the fifth contact. Place the ink cartridge in the printer and another alignment will run.
Remove the cartridge from the printer after the alignment is done. Make sure that you remove the sticky residue from the contact. Place the ink cartridge back in the printer. The ink level will now display full.