Abstract: The invention describes silver halide packet emulsion grains or crystals that are conventionally precipitated using gelatin of a given isoelectric pH, surrounded by a layer of gelatin-grafted-polymer particles wherein the grafted gelatin has a different isoelectric pH and the said gelatin-grafted-polymer particles are optionally chemically bonded to the gelatin surrounding the silver halide microcrystals. Such packet emulsions can form the basis for a mixed-packet color photographic system.

Abstract: This invention describes the composition and method of preparation of heteroflocculated packet emulsion clusters containing a light sensitive and selectively photosensitized silver halide emulsion particles and particles of photographic agents such as dye-forming coupler particles. The silver halide emulsion particles are associated with a layer of adsorbed peptizing gelatin with an isoelectric pH of P.sub.1 and the grafted gelatin of the gelatin-grafted-polymer particles comprising the photographic agent has an isoelectric pH of P.sub.2 such that P.sub.1 is different than P.sub.2. At least one of the peptizing and grafted gelatins is an isoing gelatin which is sufficiently derivatized to remove ionic groups thereof such that approaching the isoelectric pH in an aqueous solution of the isoing gelatin causes massive heteroflocculation.

Abstract: A method of preparing a monosize silver halide emulsion of which most of the silver halide crystals are of the twinned octahedral type is provided. An aqueous solution of a silver salt and an aqueous solution of an alkali metal or ammonium halide in an aqueous dispersing medium containing a protective colloid are mixed at such concentration that the silver halide is nucleated, causing the silver halide nuclei to increase in size in the presence of a silver halide solvent by Ostwald ripening to produce a population of twinned octahedral seed crystals.