US3005710A - Latensification of photographic emulsions - Google Patents

Latensification of photographic emulsions Download PDF

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Publication number
US3005710A
US3005710A US825375A US82537559A US3005710A US 3005710 A US3005710 A US 3005710A US 825375 A US825375 A US 825375A US 82537559 A US82537559 A US 82537559A US 3005710 A US3005710 A US 3005710A
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latensification
emulsion
guanidine carbonate
exposure
film
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US825375A
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Levy Marilyn
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
    • G03C5/32—Latensification; Densensitisation

Definitions

  • This invention relates to a method of increasing the effective speed of photographic emulsion by treating the emulsion with a dilute solution of guanidine carbonate after exposure and before development.
  • Latensification may be accomplished by bathing the emulsion in a solution of certain chemicals, exposure to vapors or exposure to light. This invention relates to latensification by bathing.
  • the present invention is based on the discovery that the effective speed of the photographic emulsion can be multiplied by bathing it in a dilute solution of guanidine carbonate after exposure and before development for a considerable time without producing an increased background fog even after several minutes of immersion. After ten minutes of immersion in the guanidine carbonate solution a background fog of only about 0.06 above normal is produced.
  • Example 1 for about ten minutes.
  • the emulsion is then developed with or without rinsing in water in a developer for about ninety seconds, for instance, in an Eastman Kodak de- 53,005,711! Patented Oct. 24, 1961 ice 5 veloper known in the trade as D-72 having the following composition:
  • the film is then fixed, washed and dried.
  • Example 2 A commercial silver halide film, having an ASA exposure index rating of 50 is treated as described in Example 1 using instead of a 0.5 molar solution a 2 molar solution of guanidine carbonate. The film is immersed for about one minute in this solution and then developed with or without rinsing in water for about ninety seconds at 68 F. in an Ilford Developer known in the trade as ID-62 having the following composition:
  • Films treated according to the present invention showan increase in speed up to about four times the speed of normal development in the above-described developers. Generally it may be said that an increase in the time of immersion in guanidine carbonate results in an increase in film speed.
  • guanidine carbonate solution may be used up to about a 5 molar solution and that the time of treating the film may be varied up to about twenty minutes according to the different characteristics of the exposed film and the effects desired.
  • a method of latensification of photographic silver I halide emulsions comprising treating the emulsion after exposure and before developing with an aqueous solution of guanidine carbonate whereupon the emulsion is developed in the conventional manner.
  • a method of latensification of photographic silver halide emulsions according to claim 1 in which the emulsion is treated in a 2 molar solution of guanidine carbonate for about ten minutes.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)

Description

United States Patent 3,005 ,7 LATENSIFICATION OF PHOTOGRAPHIC EMULS The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
This invention relates to a method of increasing the effective speed of photographic emulsion by treating the emulsion with a dilute solution of guanidine carbonate after exposure and before development.
Several methods of increasing the useful film speed of photographic emulsions have been described in photographic literature and used in practice. Examples of such prior methods are as follows:
The use of high speed developers or extended development time; hypersensitization or treatment before camera exposure; intensification after development; and latent image intensification or latensification between exposure and development. Latensification may be accomplished by bathing the emulsion in a solution of certain chemicals, exposure to vapors or exposure to light. This invention relates to latensification by bathing.
Prior methods of latensification by bathing after exposure and before development have included certain procedural techniques which render such methods unsatisfactory. According to these prior procedures, the film must be bathed for prolonged periods and then squeegeed and dried at normal temperatures before it can be developed in the conventional manner. The inconvenience of drying film at room temperature in the dark precludes its practical utilization as a method of increasing film speed.
The present invention is based on the discovery that the effective speed of the photographic emulsion can be multiplied by bathing it in a dilute solution of guanidine carbonate after exposure and before development for a considerable time without producing an increased background fog even after several minutes of immersion. After ten minutes of immersion in the guanidine carbonate solution a background fog of only about 0.06 above normal is produced.
The invention wfll become more apparent from the following specific embodiments:
Example 1 for about ten minutes. The emulsion is then developed with or without rinsing in water in a developer for about ninety seconds, for instance, in an Eastman Kodak de- 53,005,711! Patented Oct. 24, 1961 ice 5 veloper known in the trade as D-72 having the following composition:
The film is then fixed, washed and dried.
Example 2 A commercial silver halide film, having an ASA exposure index rating of 50 is treated as described in Example 1 using instead of a 0.5 molar solution a 2 molar solution of guanidine carbonate. The film is immersed for about one minute in this solution and then developed with or without rinsing in water for about ninety seconds at 68 F. in an Ilford Developer known in the trade as ID-62 having the following composition:
Warm water F.) cc 750 Sodium sulfite (Anhyd) gms .50.0 Hydroquinone do 12.0 Sodium carbonate (desiccated) do 60.0 Phenidone (1-phenyl-3 pyrazolidone) do .5 Potassium bromide do 2.0 Benzotriazole do .2
Water to make 1.0 liter. The film is then fixed, washed and dried.
Films treated according to the present invention showan increase in speed up to about four times the speed of normal development in the above-described developers. Generally it may be said that an increase in the time of immersion in guanidine carbonate results in an increase in film speed.
It will be obvious to those skilled in the art that various concentrations of the guanidine carbonate solution may be used up to about a 5 molar solution and that the time of treating the film may be varied up to about twenty minutes according to the different characteristics of the exposed film and the effects desired.
What is claimed is:
1. A method of latensification of photographic silver I halide emulsions comprising treating the emulsion after exposure and before developing with an aqueous solution of guanidine carbonate whereupon the emulsion is developed in the conventional manner.
2. A method of latensification of photographic silver halide emulsions according to claim 1 in which the treatment with guanidine carbonate is continued for a time period of between one to twenty minutes.
3. A method of latensification of photographic silver halide emulsions according to claim 1 in which a 1 molar solution of guanidine carbonate is used.
4. A method of latensification of photographic silver halide emulsions according to claim 1 in which a 5 molar solution of guanidine carbonate is used.
5. A method of latensification of photographic silver halide emulsions according to claim 1 in which the emulsion is treated in a 2 molar solution of guanidine carbonate for about ten minutes.
References Cited in the file of this patent UNITED STATES PATENTS Jones et a1. July 11, 1939

Claims (1)

1. A METHOD OF LATENSIFICATION OF PHOTOGRAPHIC SILVER HALIDE EMULSION COMPRISING TREATING THE EMULSION AFTER EXPOSURE AND BEFORE DEVELOPING WITH AN AQUEOUS SOLUTION OF GUANIDINE CARBONATE WHEREUPON THE EMULSION IS DEVELOPED IN THE CONVENTIONAL MANNER.
US825375A 1959-07-06 1959-07-06 Latensification of photographic emulsions Expired - Lifetime US3005710A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3275440A (en) * 1963-08-12 1966-09-27 Metalphoto Corp Process for developing photosensitized anodized aluminum plates
US3649280A (en) * 1968-11-29 1972-03-14 Eastman Kodak Co Photographic elements and compositions

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2165797A (en) * 1938-07-13 1939-07-11 American Cyanamid Co Photographic developer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2165797A (en) * 1938-07-13 1939-07-11 American Cyanamid Co Photographic developer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3275440A (en) * 1963-08-12 1966-09-27 Metalphoto Corp Process for developing photosensitized anodized aluminum plates
US3649280A (en) * 1968-11-29 1972-03-14 Eastman Kodak Co Photographic elements and compositions

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