An improved flatting agent comprising an inorganic hydrogel having a pore volume of at least 1.0 ml/g, an average particle size in the range 1 to 10 microns, and a particle size distribution such that when the flatting agent is dispersed in a coating, the fineness of grind is at least 4.75 on the Hegman scale. The inorganic hydrogel flatting agents of this invention are prepared by milling an inorganic hydrogel under controlled temperature conditions wherein a volatiles content of at least 40 weight percent is maintained, to produce inorganic hydrogel particles characterized by a pore volume of at least 1.0 ml/g, an average particle size in the range of 1 to 10 microns, and a particle size distribution such that when the flatting agent is dispersed in a coating, the fineness of grind is at least 4.75 on the Hegman scale. Also provided in accordance with this invention are improved coating compositions comprising a full gloss coating containing the above described flatting agents dispersed in the full gloss coating in from 3 to 15 weight percent loading on a solids basis.