Abstract: A process for preparing humidity-insensitive electrostatographic ferrite carrier materials comprising dry-blending ferrite-forming metal oxides, calcining the blended oxides to provide them with a saturation magnetic moment of about 6 to 30 electromagnetic units per gram, milling the calcined oxides in a slurry to reduce their particle size to about 0.8 to 1.6 microns while adding manganese oxide, copper oxide, and a sodium-free deflocculant to the slurry, pumping the milled slurry to holding/feeding tanks and adding a binder material to the slurry, spray-drying the slurry to form substantially spherical beads, screening the spray-dried beads, firing the screened beads in an ambient atmosphere at a temperature of up to about 2500.degree. F. for up to about 8 hours, deagglomerating the fired beads, and screening the beads to obtain ferrite carrier particles having controlled surface species and physical properties.

Abstract: Humidity-insensitive electrostatographic ferrite carrier materials having an average particle diameter from between about 30 to about 1,000 microns prepared by blending an essentially stoichiometric mixture of ferrite forming metal oxides, calcining the blended oxides to provide the blended oxides with a saturation magnetic moment of between about 6 to about 30 electromagnetic units per gram, milling the calcined oxides in a slurry to reduce their particle size, adding manganese oxide, copper oxide, sodium-free deflocculant, and water to the slurry to provide a slurry having about 80.