Ink cartridge and method of printing using the same

An ink cartridge for use in printing an ink on a print medium with an electronic printer. The cartridge contains ink having a viscosity of between approximately 1.5 and 10 centipoise, held in an unfelted foam (18) having a multiplicity of pores (20) disposed substantially in communication with each other and having an effective porosity of between approximately 60 and 90 pores per inch. A printhead assembly (16) is disposed in fluid communication with the foam. The foam has an effective porosity, dependent on the viscosity of the ink, whereby ink is allowed to flow from the foam to the printhead assembly during periods of operation, but is substantially prevented from flowing from the printhead assembly during periods of inoperation.