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Tabular silver halide emulsion prodn. with silver bromide:iodide core and shell - comprises seed pptn. by double jet method, shell growth at bromide to iodide ratio within miscibility gap and further silver halide shell pptn., gives good graininess to sensitivity ratio
Tabular silver halide emulsion prodn. with silver bromide:iodide core and shell - comprises seed pptn. by double jet method, shell growth at bromide to iodide ratio within miscibility gap and further silver halide shell pptn., gives good graininess to sensitivity ratio
Prodn. comprises (a) seed pptn. with 2-20 mole.% AgI at 30-50 deg. C and pBr 1.2-2.3 by the double jet method; (b) adding Ag ions, bromide and iodide in a ratio within the AgBrI miscibility gap in the growth phase and (c) pptn. of other AgX layer(s) contg. less than 20 mole% AgI. The core pref. amts. to 1-6 mole.% and the 1st shell to 3-40 mole.% of the total AgX content of the emulsion. In (b), pref. 40-70 mole.% iodide and 60-30 mole.% bormide are used. Pref. at least 2 solns. are used, one contg. Ag(+) ions and the other(s) Br(-) and I(-) ions; or at least 2 micrate emulsions are used, one a AgI and the other a AgBr or AgBrI emulsion with an iodide content up to the miscibility gap. USE/ADVANTAGE - The process makes it possible to increase the iodide content without changing the tabular habit, giving a better graininess/sensitivity ratio than usual
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