The present disclosure discloses a method implemented by a printer to control a fluid firing unit of a printhead, when said printhead is coupled to the printer, to operate according to any one of a normal printing mode and a recovery mode. According to the method, if the fluid firing unit is operated according to the normal printing mode, a first voltage is applied to the fluid firing unit to fire the fluid firing unit during a printing operation; and if the fluid firing unit is operated according to the recovery mode, a second voltage higher than the first voltage is applied to the fluid firing unit to clean the fluid firing unit.

A cosmetic handy ink-jet printer including an ink-jet head for ejecting an ink containing an inorganic pigment, an ink circulation device for circulating the ink, and a body deelectrification device for removing static electricity from a body of the printer. The ink circulation device includes an ink receptacle in which the ink is accommodated, and an ink circulation path through which the ink is circulated. The body deelectrification device is a capacitor or a grounded circuit.

A method for removing kogation, the method includes removing kogation accumulated on a surface of the upper protective layer by applying a voltage in a state where the upper protective layer is used as an anode electrode and a portion connectable to the upper protective layer via the ink is used as a cathode electrode, wherein removing kogation is performed under a first condition including applying the voltage over a first time, and then is performed under a second condition including applying the voltage over a second time longer than the first time.