Abstract: A method for grinding colorant agglomerates with a grinding medium comprising a Group IIIB and/or a lanthanide element and a Group IVB oxide. The grinding medium has a grain size of less than about 1.35 microns, and results in the production of substantially pure colorant concentrates.

Abstract: Pressure is applied to a resilient seal around the venting portion of a print head while the nozzles are elevated in the vertical position above the ink, thereby forcing ink out of the nozzles and purging the in-flow paths of air.

Abstract: The invention is directed to an ink cartridge for use in printing an ink on a print medium with an electronic printer. The ink cartridge includes an ink disposed therein having a viscosity of between approximately 1.5 and 10 centipoise. An ink cartridge has an unfelted foam therein. The foam carries the ink and has a plurality of pores disposed substantially in communication with each other. The pores have an effective porosity of between approximately 60 and 90 pores per inch. The ink cartridge further has a printhead assembly disposed in fluid communication with the foam. The foam has an effective porosity, dependent on the viscosity of the ink, wherein ink is allowed to flow from the foam to the printhead assembly during periods of operation, and is substantially prevented from flowing from the printhead assembly during periods of inoperation.

Abstract: An ink-jet printer cartridge having a center reservoir chamber and two side reservoir chambers for holding inks of three different colors is provided with ink flow pathways of special configuration for connecting the reservoir chambers to exit ports at the print element. The ink flow pathways are provided with ridges extending along substantially their entire lengths so that air bubbles cannot completely block ink flow through the pathways. The ink flow pathways are disposed such that they have a vertical component of direction over their entire length and the pathways connecting the side reservoir chambers to exit ports include duct portions disposed at compound angles relative to the axes of the cartridge so that air bubbles, because of their buoyancy, will naturally tend to drift upwardly through the inclined ducts toward the reservoir chambers during normal usage, or drift toward the exit openings when the cartridge is inverted for priming.