Patent ID: 8371684

Claim:
A method of operating an ink jet printer comprising: providing an ink system comprising: a fluid tank comprising: a generally conically shaped side wall, the side wall sloping inwardly from a top portion to a bottom portion; and a bottom surface disposed adjacent the bottom portion of the side wall; an ink composition comprising pigment disposed in the fluid tank; a first fluid conduit disposed in the fluid tank and comprising an opening adjacent and above the bottom surface of the fluid tank; and a second fluid conduit disposed in the fluid tank and comprising an opening at a location above the opening of the first fluid conduit; and performing a mixing process comprising: conveying the ink composition into the second fluid conduit and out of the first fluid conduit into the fluid tank for a first period of time, wherein the first period of time is at least 30 s; and reversing the flow of the ink composition to convey the ink composition into the first fluid conduit and out of second fluid conduit into the fluid tank for a second period of time, wherein the second period of time is at least 1 min, thereby mixing the ink composition.