Process for the preparation of iron oxide black pigments having improved acid resistance and their use

摘要

Iron oxide black pigments having improved acid resistance are obtained by treating them in aqueous suspension for 30 minutes to 200 hours at pHs from 0.5 to 14 and temperatures from 20 to 100 DEG C. The pigments aftertreated in this way are suitable for the colouring of cosmetics, pharmaceuticals and foodstuffs.