US1814788A - Augustus b - Google Patents

Description

Patented July 14, 1931 UNI-ran ,STATESI PATENT QFFICE AUGUSTUS B. DE TARTAS, OF DOUGLAS. MANOR, LQNG'ISLAND, NEW YORK rnoroeaarmo nnvEnsAI rnocEss No Drawing;

This invention relates to a photographic process, known in the art as reversal, in which positive pictures are made upon'the same support and in the same emulsion that 5 is exposed in the camera, which process comprises the development of the emulsion, after reversal process more practical in allowing;

' greater latitude in the original exposure and lnvolving a controlled production of the final. image as a means to compensate for diiferences in the original exposure, have been counterbalanced to a certain extent bythe more expensive, longer and much more difficult to perform. These improved processes necessltate such additional steps as ascertaining the characteristics of the plate or film 30 before development of the emulsion into the final positive'image or accurately timing the exposure to light of the sensitive silver salts remaining after the removal of. the first negative image; but, in general, they require judgment and precision in the control of the production of the final image.

The resent invention has for an object simplicity and time saving in the process, as it involves a minimum number of definite steps whichvremain at all times standard for a particular type of film. It also makes possible a reasonable latitude in the original exposure and the production of excellent positives of uniform quality, and the process may be carried out by an operator with no more than the usual care for the production ofnegatives, the extreme care in the control of the formation of the final positive image and the human judgment factor in arriving at the desired result being eliminated.

Application filed April 9,

its performance.

added disadvantage of rendering the process 1929. Serial no. 353,898..

'The present invention has for anotherobjectthe total elimination of flashing of the emulsion or any exposure of the latter to white light at any stage in the process after initial exposure in the camera,,the process being performed in the usual red light or in complete darkness, thus simplifying, the process, reducing its cost and likewise relieving the op- .eratorwof any undue care or responsibility in It may be remarked that the exposure of the emulsion to white light during the process of development has, in gen eral, heretofore been a basic requirement of controlled reversal processes and has invariably involved the judgment of a skilled operator in the exposure or in the control of v the formation of the'final image, exception being had to processes utilizing special apparatus automatically performing such exposure or control of the formation of the final image.

According to the present invention positives of uniform quality may be produced by aseries of standard steps performed in the usual red lighter in total darkness. The following is an example of steps performed in the order of sequence stated embodying the present invention ,1.. Development of the emulsion, after exposure in the camera, into a negative silver image;

2. Placing the emulsion into a hypo fixing bath, which removes part of the undeveloped silver salts";

3. Reversal of the image, i. e.'the bleaching or removal of the negative image;

4. Clearing the emulsion or removing the matically assured without extreme skill or;

care or judgment on the part of the operator. Carrying out the removal of part of the undeveloped salts, prior to the reversal of the image is deemed to be one of the important features of the present invention. Heretofore, in processes which involved this step of partial removal of undeveloped salts, the latter has been performed after the developed silver image has been bleached or removed and in certain cases in the open light and has involved considerable skill and judgment in its control and in the control of other steps associated with these processes in the formation of the final image. p

The partial fixing of the first negative image in the emulsion or partial removal of undeveloped salts, performed after the development of the emulsion into a silver image and before. the removal of the latter, enables the process to be carried on without exposure to white light of any kind and with no other control than the allotment of definite standard times to the several steps of the process.

While the process is applicable to any type of emulsion including negative emulsions, it produces particularly satisfactory results when using a positive emulsion.

An example of the process will now be described as applied to a motion picture film consisting of-a support of a cellulose composition with a positive emulsion thereon.

' Step J.-The film is first exposed in the usual manner in a camera. Although it is evidently desirable that this exposure be carefully timed, no more than the usual care exercised in the exposure to light of films for the production of negatives is necessary. The emulsion is then caused to be developed to a negative image which may be done by any of the well known developers. However it is preferred to use a solution of the following composition:

Developer stock solution Water 64 ounces Monomethyl paramidophenol sulphate -Q 120 grains Sodium sulphite 3% ounces Hydrochinon 480 grains Sodium carbonate 5% ounces is five minutes. The film is then rinsed for a short time.

Step 2.The film is placed in a fixing bath which is made as follows:

Fixing stock solution 1 Water 32 ounces Sodium thiosulphate (hypo) 1 ounce Sodium sulphite ounce Formal in 10 minims Or, as an alternative, any well known acid fixing solution is made up and set aside as a stock solution.

The film is placed into a bath consisting of 6 ounces of the stock solution and 32 ounces of water, the period of immersion being five minutes, and is then given a thorough Renewing stock solution Water 8 ounces Potassium bichromate 194.- grains Sulphuric acid (concern trated) 6 drams 3O minims The film is left in the reversing bath for two minutes and is then washed with water.

Other known bleaching or reversing agents may be used but it has been found that none of the latter give results as satisfactory as the one outlined above.

Step 4.-The film is placed in a clearing bath which removes the products formed in step 3 and which consists of Water .32 ounces Sodium bisulphite 1 ounce Sodium bicarbonate 1 ounce It has also been determined that this acid clearing bath isbetter adapted for clearing purposes than an alkali bath and to produce excellent results. The time factor in this step is tliree minutes when using the particularclearing bath described, the film being then again washed with water.

Step 5.The remaining salts in the emulsion are now caused to be redeveloped or converted into'a positive image. While the solution used in step 1 is very desirable for this redevelopment step, any known developer or blackening reagent that will bring out the positive image in a satisfactory manner may be used. The period of immersion of the film, for this step, in the solution of step 1, is five minutes, which is followed by a rlnsing of the film.

Step 6.The film is placed in a regular hypo fixing bath to remove all undeveloped silver salts or other unused products or impurities. The time factor for immersion of the film in this step is ten minutes, the film having the final positive image thereon being then thoroughly washed and dried in the usual manner. V y

In each of the steps described the film is kept in motion in the solutions or the latter are caused to be agitated. It is of course understood that, if so. desired, the strength" of the solutions may be varied, the timing factors in each step being correspondingl varied to produce the same desired resu ts. However, it is essential to carry out the process in the exact sequence or order of the steps given herein. The solutions described in connection with my process remain in good working order and may be reused for succeeding films until exhausted.

In practice, the strengths of the various solutions and the periods of immersion of the emulsion therein are first determined by test for a particular type or make ofemulsion. Theprocess makes it then possible to develop emulsions similar to thatof the test, but which may have been exposed to light under various circumstances, with the same certainty of satisfactory results, the strengths of the various solutions and the timing factors for each step remaining always the same. In this way, the process may be automatically carried out with great simplicity and with no more than the usual care in developing negatives.

This simplicity in the process is evidently made possible by the particular sequence of steps, performed without exposure to light, which also makes possible a reasonable latitude in the original exposure in the camera. The described process isan improvement. of substantial value in its simplicity, low cost and total elimination of extreme care or skill on the part of the'operator" The number of steps'is a minimum, since the process eliminates re-exposure of the emulsion to a controlled light or to a white light of any kind or ascertaining the rinting characteristics of the emulsion. t makes possible the production of positives of excellent and uniform quality, without requiring either extreme precision in the original exposure or extreme skill in the development of the emulsion. After having once determined the strengths of the solutions in the various steps and the timing factors of each step for a articular type of film, succeedingfilms o the same ty e, regardless of the circumstances under w 'ch they are-exposed, are developed with the same strengths of solutions and timing factors and with the same accuracy in the final result. a

While the develo ment of a motion picture film has been ciiosen for convenience in describing the invention, it is understood that the latter is'of a general character and is applicable in like manner to films, plates,

into the final positive image.

positive images in the same emulsion as originally exposed in the camera, the following steps to be performed in their order of sequence: (1) developing the emulsion after exposure in the camera into a negative image, (2) removing part of the undeveloped salts remaining in the emulsion and (3) removing the negative image from the emulsion.

2. In a photographic process of making positlveimages 1n the same emulsion as originally. exposed in the-camera, the following steps, performed without exposure to white light and in their order of sequence: ('1) developing the emulsion after ex osure in the" camera into a negative image 2) removing part of the undeveloped salts remaining in the emulsion and (3) removing the negative image from the emulsion. v

3. In -a photographic process of making positive images in the same emulsion as originally exposed in the camera, in which process the emulsion is developed into a negative image and said image is removed, the step of removing part of the undeveloped salts, re-

maining in the emulsion after its development into a negative image, performed before the removal-of the negative image.

4:. In a process of making positive images in the same emulsion as originally exposed in the camera, in which process the element is developed into a negative image and said image is removed, the step of removing part of the undeveloped salts' from said element after the development of the negative image and before the removal of the silver image, said step being performed without exposure to white light and in a definite period of time which remains constant for a particular 5. Ina process of making photographic positive images by reversal from photographic negative images in a light sensitive element, in which process the element is. de-

steps, performedin their order of sequence:

1) developing the exposed emulsion into a negative image (2) partially removing undeveloped salts from the emulsion (3) removing the negative ima e from the emulsion and 7(4) redevelopingt e remaining emulsion 7. A process of making photographic positive images by reversal from photographic negative images comprising the following steps, performed without exposure to white light and in their order of sequence: developing the exposed emulsion into a negative image (2) placing the emulsion in a fixing bath to partially remove undeveloped salts from the silver image (3) removing'the silver image from the emulsion and (4:) redeveloping the-remaining emulsion into the final positive image.

8. A process'of making photographic positive images by reversal from photographic negative images comprising the following steps, performed Without exposure to white light and in their order of sequence: (1) developing the exposed emulsion into. a negative image (2) partially removing unde veloped salts from the emulsion (3) removing the negative image from the emulsion (4) clearing the latter from the products formed during the removal of the negative image and (5) redeveloping the remaining emulsion into the final positive image.

9. A process of making photographic positive images by reversal from photographic negative images comprising the following steps,: performed without exposure to White light and in their order of sequence: (1) developing the exposed emulsion into .a negative image (2) partially removing undeveloped salts from the emulsion (3) removing the negative image from the emulsion (4) clearing the letter from the products formed during the removal of the negative image (5) developing a positive image in the emulsion and (6) removing from the latter all undeveloped salts.

10. A process of making a photographic image by reversal from a photographic negative image in a positive emulsion .Which comprises partially removing undeveloped salts from the emulsion after the latter is I developed into a negative image, removing the latter, and redeveloping the remaining emulsion into the positive ii'fiage, each of said steps being performed without exposure. to white light and in a definite period of time. 11. A process of makin a photographic image by reversal from a photographic negative image in a sensitive e ement which comprises, as sole steps in the process: (1) developing the emulsion into a negative image (2) partiall fixing said image (3) removing said image 4) removing the products formed while removing said image and (5) redevel'o ing the remaining emulsion into a positive image; all of said steps being performed without exposure to white light and each in a definite period of time which remains constant-for a particular type of .film.

In testimony whereof, I have afiixed my.

I signature to this specification.

AUGUSTUS R. on TARTAS.