E.i. Dupont De Nemours and Company

Raymond J LeStrange

Dietrich M Fabricius

Dominic M Chan

John H Bayless, Jr

Jacob Beutel

Allan R Schoenberg

Substituted diaminedithio-containing compounds useful for improving the speed of a silver halide emulsion are described. These compounds can be added in small amounts to the emulsion preferably after the emulsion has been chemically sensitized and just prior to coating. Fog levels are not greatly affected which is surprising since conventional sensitizers generally do increase the fog level.

Silver halide elements with improved speed and low fog

Zeromethine blue spectral sensitizing dyes have found utility in emulsions made without tabular grains. These emulsions are particularly useful for exposure to a light source rich in blue emission and are especially useful in radiographic elements designed for exposure to intensifying screens having such emission.

Blue spectral sensitizers for non-tabular silver halide elements

Photographic, gelatino, silver halide emulsions exhibiting improved speed/fog ratio and good hardening are described. These emulsions are made by sensitizing with 1-naphthol-4-sulfonic acid and by adding an aliphatic polyol thereto.

Photographic film with improved speed to fog ratio

Photographic, silver halide emulsions can be additionally sensitized without a deleterious increase in fog, by the addition of an alkali metal salt of 1-napthol-4-sulfonic acid. These emulsions are stable, and have good contrast and top density. The 1-napthol-4-sulfonic acid can be added conveniently from an aqueous solution and is totally compatible with conventional silver halide elements.

Silver halide emulsions with improved speed

Desensitization defects due to nonferrous metal contamination of a silver halide film sensitized by a cysteine-thiazolidine moiety are decreased by incorporating a chelating agent such as quinaldic or picolinic acid into one or more layers of the film.

Elimination of defects in cysteine-sensitized emulsions

From the complex reaction mixture of cysteine and glutaraldehyde a low molecular weight polymer is recovered for use as an additive to silver halide emulsions and developers to increase speed. Iron and nickel complexes of the purified low molecular weight polymer are similarly useful for silver halide emulsions.

Silver halide emulsion containing a purified cysteine-glutaraldehyde

A process for sensitizing photographic gelatino-silver halide emulsions with glutaraldehyde bisulfite in combination with benzene sulfinic acid.

Growing community of inventors

Hendersonville, NC, United States of America

Raymond J LeStrange