PURPOSE: To prepare the title compsn. showing an excellent dispersion stability in an aq. system and a good light resistance by mixing and treating a specific sulfate of a rosaniline deriv. seqentially with specified amts. of a finely particulate hydrophilic silica, a cupric salt, and a styrenic copolymer.

CONSTITUTION: 100 pts.wt. sulfate of a rosaniline deriv. of formula I (wherein X1 to X4 are each H or 1-3C alkyl; and R1 and R2 are each H or phenyl optionally substd. by 1-3C alkyl) is mixed and treated with 10-50 pts.wt. finely particulate hydrophilic silica and 5-15 pts.wt. cupric salt (e.g. cupric chloride), and then further with an alkali-sol. styrene-acrylic acid or styrene-maleic acid copolymer of formula II (wherein R3 is H or 1-5C alkyl; R4 is H or carboxyl group; (m) is 1-5; and (n) is 6-30). Thus is prepd. the title compsn., suitably used for a printing ink, water-base coating material, etc.