In conventional dry milling of C.I. Pigment Violet 23, the environment is heavily polluted by the necessarily formed dusts, the resulting noise and vigorous vibration during the milling process.
According to the invention, it has now been found that these shortcomings can be avoided by carrying out the comminution of the base pigment by aqueous-alcoholic milling in the presence of beads and selected pigment dispersants derived from dioxazine compounds containing basic groups, followed by a solvent finish.
Such a combination of the two abovementioned treatment operations even makes it possible to increase the capacity without the need for any other expensive investments for constructional modifications of the equipment. The pigment preparations produced in this manner simultaneously result in an improvement of the colorant in the paint and especially in nitrocellulose gravure printing upon practical application, in particular in an improvement of the gloss and a reduction in abrasiveness, compared with commercial grades known in this area.