METHOD FOR PRODUCING IMPROVED ELECTROGRAPHIC DEVELOPER

METHOD FOR PRODUCING IMPROVED ELECTROGRAPHIC DEVELOPER A method for preparing a preconditioned dry electrographic developer comprising the steps of: a) intimately mixing together an unconsolidated mass of carrier particles, and an unconsolidated mass of resin based toner particles containing charge control agent in greater concentration than desired in the final developer, the concentration of said toner in the resulting mixture being less than desired in the final developer, such mixing being for a sufficient length of time and in such a way as to pack any pores of said carrier particles with toner, to scum the surfaces of said carrier particles with charge control agent, and to abrade the surfaces of said carrier particles; and b) introducing into and intimately mixing with said resulting mixture an additional quantity of resinbased toner particles containing charge control agent in about the same concentration as desired in the free toner in the final developer, said additional quantity together with the free toner present after step (a) bringing the concentration of free toner in the final mixture up to that desired in the final developer. Mixing desirably is accomplished by tumbling in a rotating container.