JR Inkjet Cartridge flush can help extend the life of your Old and New Style HP black cartridges.

Following the instructions for ink refilling but before refilling with ink, inject 10ml of JR Inkjet Universal Cartridge Flush into the cartridge. Cover the filling hole with tape and shake the cartridge to evenly distribute the flush. Remove tape.

Set the cartridge printhead on an absorbent surface such as a paper towel and allow the flush to drain from the cartridge through the printhead

Continue with the ink refilling process per instructions. Do this the first time you refill your HP Black Cartridge.