Preparation of pigmentary form isoindoline

Abstract

A process for converting finely particled agglomerated crude isoindoline pigments of the formula ##STR1## where A is ##STR2## and B is the radical of an unsubstituted or substituted barbituric acid, or A and B are both such a barbituric acid radical, into tinctorially valuable pigmentary forms, wherein the crude pigment, which consists of primary particles having a mean size of .ltoreq.0.1 .mu.m, is subjected to shearing forces in water, and thereafter the aqueous suspension is heated at from 90.degree. to 160.degree. C. in the presence or absence of a surfactant and the pigment is isolated. Easily dispersible, low-hiding to extremely high-hiding pigments are obtained, which give brilliant colorations of improved lightfastness and fastness to weathering.

Dependencies are inferred from the claim text.