METHOD OF PREPARING AMMONIA-FREE SILVER BROMIDE OR SILVER IODIDE-BROMIDE PHOTOGRAPHIC EMULSION CONTAINING T CRYSTALS Russian patent published in 1997 - IPC

FIELD: light-sensitive emulsions. SUBSTANCE: emulsion is prepared by two-jet emulsification using introduction of silver nitrate and potassium bromide or potassium bromide/potassium iodide mixture into gelatin aqueous solution, depositing solid phase, rinsing, dispersing, and chemically sensibilizing solid phase in presence of sodium thiosulfate, sodium thiocyanide, and gold-hydrochloric acid. Method is distinguished with that emulsification is carried out in one step in excess of silver ions (pAg = 2.8-3.2) until emulsion with silver halide microcrystal size 0.020-0.075 mcm and solid phase particle content 90.25-2.5)x10³ cm^-3 is achieved, whereupon pBr = 1.5-2.5 is adjusted with potassium bromide or a mixture of potassium bromide with 2-mercaptobenzimidazol-5(6)- sulfonic acid sodium salt in amount (0.5-2.0)x10^-4 mol per 1 mol silver. Emulsion is finally cooled and allowed to stand for 168-192 h. EFFECT: increased covering power of emulsion.