When you use the cartridge of the printer, canon for example, and the cartridge ink have empty, maybe you will discard this, whereas this cartridge still work if we refill the ink. Make the hole on the cartridge and just refill the ink.
By using the injection you can refill the new ink. The properties of the printer have an option that we can perform suctioning to make the ink down to the cartridge head and we can printing well. If this action not success, use the injection to pressing the ink down, look at the following image.
Press the injection so the ink out to the cartridge head. Check using the tissue is the result a like the image below this acition success.
After all steps above done please to plaster the hole alike the new cartridge.