The sponge in the cartridge has a certain period of service life, when the sponge repeated ink, release the ink process or has been used for some time, the sponge suction capacity will drop, the adding ink can not be completely absorbed by the sponge, The excess ink in the cartridge will increase the pressure on the nozzle, causing the ink to overflow from the nozzle, which is one of the reasons a lot of people think the ink will leak when just adding or the printing effect is better than after adding ink.