Patent ID: 8657944

Claim:
An ink-jet ink comprising an aqueous vehicle, a colorant, and a first and a second cationic species wherein: i) said colorant comprises a pigment stabilized to a dispersion in said aqueous vehicle with an anionic polymeric dispersant; ii) said first cationic species is Li + and has a molar concentration per unit weight of ink of M1; iii) said second cationic species is any member or any combination of members selected from the group consisting of Na + , K + , Rb + and Cs + , and has a molar concentration per unit weight of ink of M2; and iv) the molar ratio of the first cationic species to the total cation concentration (Mtot) satisfies equation 1 as follows: 0.20 <M 1 /Mtot< 0.45 (eq. 1) wherein Mtot is the cumulative molar concentration of the first and second cationic species per unit weight of ink (Mtot=M1+M2).