A number of ink-jet ink sets utilize water-soluble dyes, which are highly soluble in water, in order to achieve the right color gamut. Examples of patents that are directed to ink-jet ink sets for achieving the desired color gamut include U.S. Pat. No. 5,108,504, issued Apr. 28, 1992, to Loren E. Johnson et al and entitled "High Chroma Color Dye-Set for Use in Ink-Jet Inks Employing Polysaccharide-Containing Vehicles"; U.S. Pat. No. 5,143,547, issued Sep. 1, 1992, to William D. Kappele and entitled "Specific Dye Set for Thermal Ink-Jet Printing on Plain and Coated Papers"; U.S. Pat. No. 5,145,519, issued Sep. 8, 1992, to William D. Kappele and entitled "Specific Dye Set for Thermal Ink-Jet Printing"; U.S. Pat. No. 5,185,034, issued Feb. 9, 1993 and entitled "Ink-Jet Inks with Improved Colors and Plain Paper Capacity"; and U.S. Pat. No. 5,534,051, issued Jul. 9, 1996, to Hiang P. Lauw and entitled "Specific Dye Set for Thermal Ink-Jet Printing"; all of the foregoing cited patents are assigned to the same assignee as the present application.
However, many dye-based inks, after being printed, exhibit poor water-fastness. There is an increased demand by consumers on the permanence or durability of ink-jet print, including water-fastness, light-fastness, smear-fastness, smudge-fastness, etc. The purpose of the present invention is to improve the durability of water-soluble dye-based inks, especially the water-fastness, smear-fastness, smudge-fastness, and light-fastness, lumped together under the term "color permanence", of such inks.