Abstract: Low-silking iron oxide yellow pigments having improved color qualities are produced by a novel method which utilizes both precipitation process and the Penniman process. Pigments are nucleated and grown by precipitation to achieve multiplication factor of 2.5 to 7 and additional pigment growth is carried out by the Penniman process.

Abstract: Acidic liquids, such as galvanic electrolyte solutions for metal electroplating, contain a surfactant and a foam inhibiting agent which is a perfluoroalkyl-containing ester of phosphoric acid.

Abstract: Iron oxide particles containing at least 5% by weight of iron (II) content calculated as FeO are stabilized against atmospheric oxidation by a coating of at least one compound containing boron and those particles are useful as coloring pigments and magnetic particles in magnetic recording media.

Abstract: Spherical agglomerates of surface-stabilized primary particles substantially consisting of iron, having a BET surface of about 5 to 50 m.sup.2 /g, measured on the agglomerate, in non-pyrophoric form and having a bulk density of about 0.5 to 2.0 kg/l and an agglomerate diameter of about 0.5 to 10 mm are produced by(a) reducing in dry phase particles consisting essentially of iron oxide,(b) intensively dispersing the particles in liquid phase,(c) coating the particles with an inorganic and/or organic coating optionally containing corrosion inhibitors,(d) separating the particles from the liquid phase by evaporating the volatile components with a continuously rotating and simultaneously tumbling movement, and(e) subjecting the resulting granulates to a thermal treatment. The particles are especially useful for the production of magnetic recording media.

Abstract: A pigment of a magnetic metal or alloy thereof carrying, in about 0.2 to 30% of the weight of the metal or alloy, a coating of at least one member selected from the group consisting of an ortho-silicic acid ester, a hydrolyzate thereof and a condensation product thereof. Optionally it also carries a corrosion inhibitor. The coated pigment is produced by suspension of the untreated pigment in a liquid medium containing the ortho-silicic acid ester or derivative thereof, and optionally the corrosion inhibitor, followed by separation and drying at 50.degree. to 250.degree. C. The resulting pigment is non-pyrophoric and of high performance properties suitable for use in magnetic recording media.