Patent ID: 7501016

Claim:
A gray ink composition, comprising: an ink vehicle; a black pigment dispersed in the ink vehicle; at least two color pigments dispersed in the ink vehicle; an anionic dispersant: a) dispersed in the ink vehicle; b) associated with at least one portion of a surface of either the dispersed black pigment or at least one of the at least two dispersed color pigments; or c) combinations thereof; and an anionic surfactant which adsorbs to or coats at least one other portion of the surface of either the dispersed black pigment or at least one of the at least two dispersed color pigments; or combinations thereof; wherein the at least two color pigments include a cyan pigment having a pigment load sufficient to provide visible absorbance at peak maxima ranging between about 0.001 and about 0.1 at a 1:2,500 dilution of the ink:diluent; and at least one of a violet pigment having a pigment load sufficient to provide visible absorbance at peak maxima ranging between about 0.005 and about 0.2 at a 1:2,500 dilution of the ink:diluent, and a magenta pigment having a pigment load sufficient to provide visible absorbance at peak maxima ranging between about 0.001 and about 0.2 at a 1:2,500 dilution of the ink:diluent; and wherein the at least one other portion of the pigment surface adsorbed with or coated by the surfactant is different than the at least one portion associated with the anionic dispersant.