Process for fine division of organic pigments

A process for the manufacture of finely divided organic pigments comprising the steps of spraying a coarsely crystalline crude pigment and/or a poorly dispersible prepigment in suspension form through nozzles to a point of conjoint collision in a reactor chamber enclosed by a housing in a microjet reactor to form a pigment suspension, wherein the microjet reactor has a gas entry side and a product and gas exit side, passing a gas or an evaporating liquid into the reactor chamber through an opening in the housing for the purpose of maintaining a gas atmosphere in the reactor chamber, and removing the pigment suspension and the gas or the evaporating liquid from the microjet reactor through a further opening in the housing by means of overpressure on the gas entry side or underpressure on the product and gas exit side.