Abstract: An organic solvent-based printing ink composition which comprises a cationic dyestuff of the indole class, an organic solvent, an organic acid which preferably is a resin acid, soluble in the organic solvent, and optionally an organic pigment. The cationic dyestuff is formed (in situ) from its carbinol precursor. The compositions show for example high color strength and excellent rheological properties and can be used in publication or packaging gravure flexographic, lithographic or letterpress printing processes.

Abstract: Pigment compositions comprising an organic pigment and a combination of at least two normally water-soluble coloured compounds (dyes) of opposing charge, i.e. of at least one anionic and one cationic dye are provided. The compositions impart improved rheology on non-aqueous pigment based printing inks and paints.