Aqueous based jet ink

An ink composition suitable for ink jet printing operations, comprising a pigment, water, and a surfactant, said composition having a surface tension of less than 30 dynes/cm, a viscosity from about 1.6 to about 7.0 centipoises at 25.degree. C., an electrical resistivity from about 50 to about 2000 ohm-cm, and a sonic velocity from about 1200 to about 1700 meters/second, wherein the pigment is present in an amount from about 7% to about 15% by weight of the ink composition, the water is present in an amount from about 70% to about 90% by weight of the ink composition, and the surfactant is present in an amount from about 0.2% to about 0.8% by weight of the ink composition.

A method of printing cancellation marks on a stamp, comprising forming an ink composition comprising from about 7% to about 15% colorant by weight of said ink composition, from about 70% to about 90% water by weight of said ink composition, and from about 0.2% to about 0.8% surfactant by weight of said ink composition, said composition having a surface tension of less than about 30 dynes/cm into droplets, projecting a stream of the droplets to the stamp, and controlling the direction of said stream electronically so that the droplets form a printed image on said stamp.

The method of clam 9, wherein the colorant is a pigment.