Brother MFC 3100C Reset ink sensor

You just wrap each cartridge in a piece of black garbage bag,and tear a small hole in the bottom for the jet to poke through . just make sure that all sides are still covered by the bag and insert back into the printer as usual bag and all. the light sensor that reads ink levels thinks they are all full and won't give you an error.

just be careful not to run them completely dry or you will damage your print head.