How to Fill HP 21 Ink Cartridges

By Catherine Johnson

  • Overview

    Frequently replacing your empty printer-ink cartridges is an expensive and inconvenient task. Refilling your ink cartridges is a simpler and more affordable option. By purchasing one of the many bulk printer inks that are now widely available, you can reuse your plastic printer cartridge several times. Extending the life of your ink cartridge in this way not only helps the environment, but also cuts down costs and provides the convenience of refilling your ink on demand. Here is how you can easily fill your black HP 21 ink cartridges in just a few steps.
    Refill your HP 21 cartridge saves time and money.
    • Step 1

      Turn on the printer. Lift the printer cover. The ink cartridges should be located in the center. Remove the HP 21 cartridge by snapping it out of its holder. Place it on the paper towels.
    • Step 2

      Using the edge of a sharp knife, peel the HP sticker off the top of the cartridge. There should be five small holes underneath.


    • Step 3

      Fill the syringe with 15ml of the pigmented black ink. Insert the syringe needle into the single hole located slightly away from the other four holes. Make sure the needle goes deep into the cartridge and reaches the bottom.
    • Step 4

      Inject the ink slowly into the cartridge. The sponge located on the inside should become full.
    • Step 5

      Remove the syringe and firmly reapply the sticker over the five holes.
    • Step 6

      Turn the cartridge upright, with the cartridge bottom facing downward. Hang the cartridge over some paper towels for several hours. Excess ink will drip from the bottom. Do not let the cartridge and paper towels touch each other.
    • Step 7

      Insert the bottom of the cartridge back into its holder in the printer and snap the top into place. Close the printer lid and paper tray.
    • Skill: Easy
    • Ingredients:
    • Syringe
    • Sharp knife
    • Black, pigmented ink: ACSI WJ1010
    • Paper towels
    • Tip: Run your printer's head-cleaning cycle several times before beginning to print.
    • Tip: Leave the cartridge to hang over the paper towels overnight for best results.

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