If you know how to refill the ink in a cartridge yourself
, it would be useful. First of all, you should read the instructions given about refilling the cartridge. Ensure that you use the right ink for a particular cartridge. You should pump the ink into the cartridge by inserting the long needle from the refill bottle into the refill hole of the cartridge. However, while doing it, just make sure that the ink does not overflow. You must also remember to clean the injector tools completely when moving from one color to the other. If you don't do so, the colors would mix which would lead to tainting. You have to also make sure that the ink jet does not leak and the printer displays all the colors properly.
You can make online purchase of inkjet cartridges. There are several providers out there dealing in popular HP Inkjet and other cartridges.