Patent ID: 8083338

Claim:
A radiation-curable ink-jet ink set comprising only one radiation-curable ink-jet black ink and at least three radiation-curable ink-jet color inks wherein the radiation-curable ink-jet black ink includes at least one black pigment, at least one color pigment, at least one surfactant, at least one photoinitiator and at least one radiation-curable compound, wherein the wavelength of the absorption maximum of the color pigment is located between 500 and 700 nm; wherein the at least one radiation-curable compound is a monofunctional or polyfunctional acrylate monomer; wherein the photoinitiator is present in an amount of 1-6 weight % of the total ink weight; wherein the ink-jet black ink is free of a fluorinated surfactant; wherein the ink-jet ink has a viscosity of less than 30 mPa·s at a shear rate of 100 s −1 and at 25° C.; and wherein the radiation-curable ink-jet black ink has a chroma C* of less than 1.5.