US1952572A - Method of treating photographic films - Google Patents

Description

Patented Mar. 27, I934 PATENT OFFICE METHOD OF TREATING PHOTOGRAPHIC FILMS Norman E. Titus, New York, N. Y.

No Drawing. Application July 9, 1932, Serial No. 621,745

4 Claims.

This invention is directed to a method of treating photographic films after the same have been exposed, and has for one of its objects the provision of a method for the removal of scratches and other imperfections on the sensitized face of the film.

My invention while adapted for use in connection with all kinds of photography is particularly well adapted for the treatment of films employed in newspaper work, for example, where enlargements are usually made from the original film, any scratches or other imperfections on the film being of course very pronounced and objectionable on enlargement.

More specifically the present invention provides a method for treating films after exposure but before final processing whereby the desirable results above mentioned are obtained.

Still more specifically the present invention provides a method for the treatment of films in which after exposure the sensitized surface of the film is subjected to the action of heat, the degree of heat employed being just sufficient to effect a slight flowing or smoothing of the sensitive coating of the film to a point where the scratches or other imperfections in this coating will disappear, or be so much reduced as to be negligible.

In the practice of my improved method the sensitive surface or emulsion of an exposed film after developing but before fixing is subjected to the action of heat in a dark room, the heating being properly controlled so as to eliminate all possibility of damage to the film. This slight heating of the photographic emulsion causes a spreading or flowing of the same whereby any scratches or other imperfections on the surface of the emulsion will be filled in to such a extent as no longer to be objectionable.

I appreciate that this application of heat to the emulsion is necessarily a delicate operation and that the film must not be exposed to actinic rays in the process,so for these reasons I propose to subject the sensitized surface of the film to the action of infra-red rays, from any suitable source but preferably generated electrically, to

permit me to avail myself of the nicety of control found in electrical apparatus.

The film to be treated can be kept in a dark room from which all light is excluded, the infra red rays from a suitable source exterior to the dark room being directed to the surface of the photographic emulsion on the film through a suitable barrier which will pass infra-red rays, but will filter out all actinic rays. For example, a barrier of material such as vulcanite may be substituted for the usual red dark room window, thus permitting the infra-red source to be located outside the dark room where it is readily accessible, and permitting of the exclusion of all actinic rays from the film so that there is no danger whatsoever of fogging of the film during the practice of my invention.

I do not wish to be limited to any particular device for the source of the infra-red waves but for the purpose of this application I may mention an ordinary copper bowl electric heater, a well known commercial article, as useful for the infra-red source.

In practice this heater may be placed in front of the above mentioned vulcanite barrier of the dark room and the film with its emulsion side toward the infra-red source passed behind the barrier. It will be appreciated of course that the input of this heater may be controlled to a nicety, and that by properly controlling the distance of the heating device from the film, and the time of treatment, the desired results can be obtained to perfection.

As above mentioned the heat is applied to the emulsion of the film in accordance with the present invention after the film has been exposed and before fixing.

By the foregoing method it will be appreciated that all imperfections such as striations, scratches, etc. on the emulsion of the film will effectively be removed so that the enlargement from such film will be free of such imperfections. This is of great value in the newspaper industry, for instance, where the pictures originally taken are usually enlarged before publication and where usually the pictures are taken under conditions where the film is likely to be roughly handled be fore being developed and fixed. My method is also useful in other fields of photography, as in the motion picture industry, for instance, where the pictures are taken on a small scale and are ver greatly enlarged on projection.

What I claim is:-

1. The method of treating photographic films to eliminate scratches and other imperfections in the emulsion coating of the film which method comprises imposing non-actinic light rays upon the emulsion of a previously exposed but unfixed film to heat the emulsion sufficiently to effect a slight flowing of the emulsion whereby the scratches and other imperfections therein will be smoothed out.

2. The method of treating photographic films to eliminate scratches and other imperfections in the emulsion coating of the film which method comprises exposing the film, developing and then before fixing subjecting the emulsion of the film to the action of infra-red rays to the exclusion of actinic rays to heat the emulsion sufficiently to effect a flowing of the emulsion whereby the surface of the same will be smoothed out.

3. The method of treating photographic films to eliminate scratches and other imperfections from the emulsion surface of the same, which method comprises directing electrically generated light rays upon a medium capable of permitting of the passage of non-actinic rays while preventing the passage of actinic rays, and exposing the emulsion of an exposed but unfixed film to the light waves passed by said medium at such a distance from the source of the rays and for a surficient length of time to effect a slight heating of the emulsion sufficient to cause a slight flowing of the emulsion with a resultant smoothing of the surface of the emulsion.

4. The method of treating photographic films which comprises directing electrically generated light rays upon a medium capable of permitting of the passage of non-actinic rays while preventing the passage of actinic rays, exposing the previously exposed, developed, but unfixed emulsion of a photographic film to the non-actinic rays passed by said medium while controlling the time of exposure and the distance from the source of the non-actinic rays so that the emulsion is heated sufficiently to cause a slight flowing of the emulsion with a resultant smoothing out of said face of the emulsion.

NORMAN E. TITUS.