US2009689A - Method of producing films in natural color - Google Patents

Description

July 30, 1935. l w T. cREsPlNl-:L 290091589 METHOD `OF PRODUCING FILMS IN NATURAL COLOR Filed Aug. 19, 1950 f//ff/ ,C h l; @ed fg/@Mg .Secondary Ema/Sion 6 E Remo l/a/ of Ex'cess Rea Jc/e wvo/MASK Y Patented July 30, 19.35

METHOD OF PRODUCING FILMS IN NATURAL COLOR William T. CrespneL Los Angeles, Calif., assignor, by mesne assignments, to Hughes Industries C`o. Ltd., a corporationof Delaware Application August 19, 1930, Serial No. 476,251

22 Claims.

My invention relates to`a methodof producing films in natural color, employing a positive rlhn vhaving two layers of sensitized emulsion superimposed on one side thereof, this film being termed a sandwich illm.

It is an object of my invention to provide a process for producing a color positive in which the image appears in natural color, and it is a further object of the invention to provide a process which will give satisfactory or substantially perfect results in the production of a color lm without the exercise of extreme care in the performance of the process.

It is a further object of the invention to provide a process of the above character by which a color iilm may be vproduced from color value negatives ina minimum period of time and with a relatively small expenditure of labor.

Further objects and advantages of'my invention ywill appear throughout the disclosure of a preferred manner of performing my new process, which refers to the accompanying drawing diagrammatically showing my invention.

For the purpose of segregating the principal steps of my invention, I shall in the drawing and hereinafter in the description designate same by letters.

(A) Preparation of color value negatives In my process I prefer to employ color value negatives representing yellow-red and blue-green values of a color image. Owing to the fact that ,there are many methods known to the art of color photography for the production of color value negatives, and since this invention relates principally 'to a new process for producing a positive film in color, it is not necessary to further describe the production of the color value negatives employed in the process.

Although other types of lm may be employed in the practice of my invention, I prefer to use the type of lm III shown in the diagrammatic disclosure of step B of my invention, which consists of a transparent base, .generally of celluloid, a thin primary gelatine substratum on the front face of the transparent base, a primary layer of sensitized emulsion, a secondary gelatine substratum, and an outer or secondary layer of sensitized emulsion.v 'I'he primary substratum has its principal utility in securing the primary sensitized emulsion to the transparent base, and the secondary'substratum serves to separate and to act as' 'a barrier between the primary and secondary sensitized emulsion coatings. Incorporated either in the emulsions or in the secondary substratum of the positive film I0 is a yellow dye whichprevents penetration of light from one emulsion to the other.

(B) Printing positives from color value negatives In the printing of the positive l0, the red color value negative is placed adjacent to the transparent base, and the primary sensitized emulsion is printed by light which passes through the red color value negative, the transparent base, and the primary gelatine substratum. The blue color value negative is placed adjacent to the secondary sensitized emulsion, and the secondary sensitized emulsion is printed directly from the blue color value negative. The printing of the primary and secondary sensitized emulsions may be carried on simultaneously or separately. y

In printing I find it advisable to diilerentiate between the voltage used in printing the outer and inner emulsions. To clarify this I would use volts to the outer or secondary emulsion and volts to the inner or primary emulsion. The reason for this is that it is an advantage in developing, since the developer attacks more readily the outer image and has to penetrate through to the inner image, during which time the outer image is still developing, but because of the additional exposure to the inner emulsion it will develop more quickly when the developer has thoroughly saturated it.

(C) Developing, fixing, and washing positive This step of the process I carry on in the usual manner of developing photographic positives and have used with satisfactory results a number of developers, preference among which is given to Amidol developer, which produces so-called at images, although vgood results may also be obtained from standard developers, such as East-A man developer No. 16. After treatment by the developer solution, the image is fixed and then thoroughly washed, whereupon the next step of vthe process may be carried on with the lm wet or with the lm dried.

' `(D) -Hordanting secondary emulsion `Although it is possible to continue the operation andA perform the operation of mordanting the outer or secondary emulsion while the film is still wet, I ilndthat if the illm is iirst dried thoroughly, the coloring operations may be carried on to best advantage. The positive film is conducted through a bath or solution of potassium tri-iodide and potassium iodide characteristics with an addi- 'r tion of acetic acid. A suitable formula for the mordant for basic dyes which I employ in this step of the process is as follows:

Iodine resublimated 2 grams Potassium.iodide 25 grams Acetic acid (glacial) 50 c. c. of 10% solution Water to make 500 c. c.

The lm is allowed tol remain in this solution for a period of time sufficient to penetrate through and bleach the surface image or secondary sensitized emulsion. The secondary gelatine substratum separatingthe two layers of emulsion acts as a retardant to the mordanting solution and will prevent the mordantiing solution from entering the silver image of the primary sensitized emulsion. If the exposure and development are carefully adjusted, I nd that this operation may be consistently performed without affecting the image of the primary sensitized emulsion in a time of approximately one and one-half minutes. The film is then run into a wash tank of running water to thoroughly wash out the excess of mordanting solution. The above mordanting formula is the preferred proportion, but I have found that the proportions may be considerably varied without greatly aecting the results obtained. The potassium iodide is the predominating chemical employed, and the potassium tri-iodide and acetic acid are the ancillary chemicals. I find that the following proportions may be satisfactorily employed:

Iodine resublimated 1 1/4 to 2 grams Potassium iodide 25 to 50 grams Acetic acid 50 to 100 c. c. of 10% solution Water to make 500 c. c.

(E) Arrestz'ng of mordantng action From the wash tank of the previous step of the process the film is carried into a solution of an arresting agent of bisulphite character, such as either potassium metabisulphite or sodium bisulphite, good results being obtained where a 10% solution is employed. In this solution the action of the mordanting solution is immediately stopped, and the mordanting solution is cleared from the film. 'I 'his operation requires from one-half minute to one minute, depending upon the strength of the arresting solution. The film is again thoroughly washed in a bath of running water to remove the clearing or arresting solution.

(F) Red-dyeing of secondary emulsion I SafranineY 1 gram in 100 c. c. of water Chrysoidine Y 1 gram in 100 c. c. of water From this stock/solution I prepare the red-dyeing bath in the following proportions:

chrysoidine Y 9o c. c. Safranine Y 10 c. c. Acetic acid 1 c. c.

Where this solution is made in accordance with the above formula, the red-coloring action may be accomplished by running the film into the bath thereof for a period of approximately three minutes, during which time the mordant absorbs the basic dye and becomes or is converted into a brilliant orange-red.

(G) Removal of excess red-dye The film is now carried into running water which removes the excess vred-dyeing solution from the film, leaving the silver deposit forming the image of the secondary emulsion colored orange-red, the strength of the color being in proportion to the quantity of the silver deposit. If the correct dyes are used and in their correct proportions, substantially as noted above, this removal of the excess red-dye will take approximately ve minutes. At this time the film carries a top'image with a basic red dye and a lower image in the primary sensitized emulsion which is still black and white, the two images being separated by the intermediate substratum.

(H) Blue-toning primary Aemulsionr vsolution of low acid content. I find that great care must be exercised in the use of the more potent acids, such as hydrochloric acid, which .affect the iodide mordant so as to increase the opacity of the red-dye image, which, if correctly executed, is very transparent. For this purpose I prefer to use a ferrie bath in which acetic acid is substituted for the usual hydrochloric acid, the

ferrie bath being made substantially in accordance with the following formula:

Ammonium persulphate 31/2 grams Ferric alum 21/2 grams Ferricyanide 241/2 grams Acetic acid 10 c. c. of 10% solution Water to make 1000 c. c.

This bath will not affect the red-dye image of the secondary emulsion but will readily penetrate through the secondary substratum and in four or five minutes convert the image of the primary substratum to a blue-tone image. After being subjected to the ferrie solution for a length of time gauged in accordance with the strength of the solution, the film is again washed in running water. f

(I) Clearing or firing the blue-teme primary emulsion Y Since the red dyed image is relatively transparent and the ferrie image is somewhat opaque, it is necessary to fix the ferrie image to bring its transparency into a suitable balance with the red-dye image. However, the ordinary hypo fixing bath cannot be used for this purpose since it destroys the silver iodide mordant so as to result in release of the red dye from the image of the secondary emulsion. For the purpose of fixing the ferrie image I employ a 10% solution of potassium iodide. Since the mordanted image of the secondary emulsion is composed of silver iodide, this fixing solution has no effect upon `the red-dye image but will effectively clear the blue image of the primary emulsion in a period of about three minutes, after which the film is again washed. An added advantage of the use of this bath is the fact that if it were possible to use a hypo sulphite fixing solution, a prolonged washing would then be necessary to remove all traces of hypo from the lxn itself, and

i Water this prolonged washing would impair both of the colored images. Thus, where the iodide clearing solution is used, a brief wash oi' from two to four minutes is suilicient and completes the operation of producing the positive film in color.

If a sound track is to be printed on the positive film, I find it advisable to-'print such sound track by placing the sound negative against the secondary emulsion and to print same with greater light exposure than that used in the printing of the red image, ln order that the light will penetrate and also expose the sound track portion of the primary emulsion. y

A transparent dyed image is not a suitable medium for sound recording because the rays from the exciter lamp, which is part of the projector equipment, will readily penetrate the dyed image, and the resulting sound would be very weak and poor in quality. The sound track could be, of course, suitably protected by a varnishing solution, leaving it in a black and white condition, but as this adds greatly to the cost of production, it is an operation to avoid. Therefore, as already explained, I prefer to print the sound to a density which will penetrate both the top and bottom emulsions. Consequently, when the film is completely colored, the sound track is composed of both red and blue. 'I'hese colors, V being superimposed, give the sound track an appearance of more or less opaque strlations on a transparent base.

In order to clearly disclose a preferred embodiment of my invention, I have hereinbefore confined the process to use with the red color image on the outside of the film or in the secondary sensitized emulsion. It will be perceived that in the foregoing I have clearly disclosed a process wherein the image of the secondary emulsion or outer emulsion is first mordanted and then dyed. and the underneath or primary sensitized emulsion is then toned or converted to the desired color without in any way affecting the image in the outer or secondary sensitized emulsion. Although I have hereinbefore disclosed the red image on the secondary emulsion and the greenblue image on the primary emulsion, this order or placingmay be reversed. The green-blue image may be imprinted in the outer or secondary emulsion, and the 'orange-red image may be imprinted through the film IB and in the primary or inner sensitized emulsion. In so doing, the principal steps of the process are adhered to. The outer emulsion is first mordanted and then dyed with a blue-green basic dye,- after which the inner or primary emulsion is converted to a red color.

The outer image may be mordanted by subjecting it to a solution having substantially the following proportions, in which potassium iodide is the principal chemical:

Iodine Potassium iodide Acetic acid 3 grams 25 grams y 4 grams 2000 c. c.

. may be accomplished in apln-oximatelyA five minutes, after which the film is passed through running water to clear the highlights. The inner image is then red-toned by use of a uranium toning bath, which may be made up in accordance with the following formula:

Potassium oxalate 5 grams Uranium nitrate 5 grams Potassium ferricyanide 5 grams Hydrochloric acid 2c.c.

Water 1000 c. c.

If it is necessary to print a sound record on this color positive, such sound record is printed after step B, or at the time indicated at B in the drawing, from the front or surface of the film and not through the back. In printing I do not confine the sound record necessarily to the surface emulsion but simultaneously print the primary or inner emulsions in order that the final colored sound record will be represented in both red and green and will therefore approach very near to black and white.

In the foregoing description I have set forth the process in what I believe to be its most practical form. I nd, however, that the steps of the process may be deviated from, Within reasonable limits, without seriously affecting the results to vbe obtained, and I contemplate that further experience in the practice of the invention may develop advisable variations lying Within the scope of the process hereinabove fully explained.

I claim as my invention:

1. A method of producing a color positive from a film having a primary sensitized emulsion and a secondary sensitized emulsion in superposed relation, comprising: printingv photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images; mordanting the film; blue-toning said primary emulsion by appli-v cation thereto of a blue-toning solution containing ferrie salts and having no affinity for the mordant -carried in said secondary emulsion; andclearing said primary emulsion to render the blue-toned image thereof more transparent, by subjecting the film to a solution of potassium iodide.

2. A method of producing a color positive from a film having a primary sensitized emulsion and a secondary sensitized emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from redsand blue color value negatives; developing said images; mordanting the image of said secondary emulsion for a basic dye by use of a solution having potassium iodide as its principal constituent; arresting the action of the mordant by subjecting it to a bisulphite solution; applying red basic dye to said secondary emulsion; removing excess of red dye from said film; blue-toning said primary emulsion by application thereto of a blue-toning solution containing ferric salts and having no ainity for the mordant carried in said secondary emulsion; and clearing said primary emulsion to render the blue-toned image thereof more transparent, by subjecting the film to a solution of potassium iodide.

3. A method oi' producing a color positive from a lm having a primary sensitized emulsion and a secondary sensitized emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images; mordanting the image of said secondary emulsion for a basic dye by use of a solution having potassium iodide as its principal constituent; arresting the action of the mordantl by subjecting it to a bisulphite solution; applying red basic dye to said secondary emulsion; blue-toning said primary emulsion by application thereto of a blue-toning solution containing ferric salts; and clearing said primary emulsion to render the blue-toned image thereof more transparent, by subjecting the film to a solution of potassium iodide.

4; A method of producing a color positive from a iilm consisting of a transparent base, a primary emulsion thereon, and a secondary emulsion over said primary emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images; mordanting the image of said secondary emulsion for a basic dye; applying red basic dye to said secondary emulsion; blue-toning said primary emulsion by application thereto of a blue-toning solution containing ferric salts and havingno afiinity for the mordant carried in said secondary emulsion; and clearing said primary emulsion to render the blue-toned' image thereof more transparent by' subjectingthe lm to a solution'containing an iodide.

5. A method of producing a color positive from a lm consisting of a transparent base, a primary emulsion thereon, and a secondary emulsion over said primary emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images; mordanting the image of said secondary emulsion'for a basic dye by use of a solution having potassium iodide as its principal constituent; arresting the action of the mordant by subjecting it to a bisulphite solution; applying red basic dye 4to said secondary emulsion; removing excess of red dye from said film; blue-toning said primary emulsion by application thereto of a blue-toning solution containing ferrie salts and having no ailinity for the mordant carried in said secondary emulsion; and clearing said primary emulsion to render the blue-toned image thereof more transparent, by subjecting the lm to a solution of potassium iodide.

6. A method of producing a color positive from a lm consisting of a transparent base, a primary emulsion thereon, and a secondary emulsion over said primary emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images;l mordanting the image of said secondaryemulsion for a basic dye by subjecting same to a solution of substantially two grams oi' iodine, twenty-five grams of potassium iodide, and ftycubic centimeters of 10% solution of acetic acid, together with suiiicient water to make a total of five hundred cubic centimeters of mordanting solution; applying red basic dye to said secondary emulsion; removing excess of red dye from said-film; blue-toning said primary emulsion by application thereto of a blue-toning solution having no ainity for the mordant carried in said secondary emulsion; and clearing said primary emulsion to render theI blue-toned image thereof more transparent.

7. A method of producing a color positive from a film consisting of a transparent base; a primary emulsion thereon, and a secondary emulsion over said primary emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; developing said images; mordanting the image of said secondary emulsion for a basic dye by subjecting same to a solution of substantially two grams of iodine, twenty-five grams of potassium iodide, and fifty cubic centimeters of 10% solution of acetic acid, together with suilicient water to make a total of five hundred cubic centimeters of mordanting solution; applying red basic dye to said secondary emulsion, said red basic dye including substantially nine parts of chrysoidine Y, one part of safranine Y, and a small amount of acetic acid added thereto; removing excess o red dye from said iilm; bluetoning said primary emulsion by application thereto of a blue-toning solution having no afnity for the mordant carried in said secondary emulsion; and clearing said primary emulsion to render the blue-toned image thereof more transparent.

8. A method of producing a color positive from a film having a primary sensitized emulsion and a secondary sensitized emulsion in superposed relation, comprising: printing photographic images on said primary and secondary emulsions respectively from red and blue color value negatives; printing a single sound track through the cooperating edge portions of both of said emulsions to form identical and superimposed sound-representing images in said primary and secondary emulsions which, when subsequently toned red and bluefwill produce black striations along the sound track of the positive lm; developing said images; mordanting the image of said secondary emulsion for a basic dye; 'applying red basic dye to said secondary emulsion; removing excess of red dye from said iilm; bluetoning said primary emulsion by application thereto of a blue-toning solution containing ferri salts and having no ainity for the mordant carried in said secondary emulsion; and clearing said primary emulsion With a solution of soluble iodide to render the blue-toned image thereof more transparent. v

9. A method of producing a color positive from a lm having a primary sensitized emulsion and a secondary sensitized emulsion in superposed relation, comprising: imprinting said primary and secondary emulsions respectively with cooperating images; developing said images; mordanting the image of said secondary emulsion to receive a dye; applying a dye to said secondary emulsion; subjecting said lm to a toning solution containing erric salts to convert the image of said primary emulsion yto a desired color; and clearing said primary emulsion by subjecting the lm to an iodide-containing solution.

10. A method of producing a color positive from a film having a primary sensitized emulsion and a secondary sensitized emulsion, comprising: imprinting said primary and secondary emulsions respectively with 'cooperating images;

imprinting a sound track simultaneously through.

lsion to receive a dye; applying a dye to said secondary emulsion; and then converting the image 'of said primary emulsion to a desired color r tone.

11. A method of producing a color positive from a film having a primary sensitized emulsion and a secondary sensitized emulsion, comprising: imprinting said primary and secondary emulsions respectively with cooperating images; imprinting a sound track simultaneously through both of said emulsions so that superimposed identical sound track images will be impressed on both of said emulsions; developing said images; mordanting the image of said secondary emulsion to receive a dye; applying a dye to said secondary emulsion; and subjecting said illm to a toning solution to convert the image of said primary emulsion to a desired color.

12. A method of producing a sound track in a color positive having primary and secondary sensitized emulsions, comprising: imprinting said primary and secondary emulsions respectively with cooperating color value images; imprinting a sound track simultaneously in both of Vsaid emulsions so that superimposed identical sound track images will be impressed on both of said emulsions; developing the images contained in said emulsions; and subsequently changing the images of said emulsions from black and white character to complementary colored images.

13. A method of producing a sound track in a color positive having primary and secondary sensitized emulsions, comprising: imprinting said primary and secondary emulsions respectively with cooperating color value images; from a single sound record imprinting a sound track.

through both of said emulsions so that superimposed and identical sound track images will be impressed simultaneously on both of said emulsions; developing the images contained in Asaid emulsions; and subsequently changing the irnages of said emulsions from black and white character to complementary colored images.

14. A method of producing a color positive from a iilm having a primary sensitized emulsion and a secondary sensitized emulsion inl superposed relation, comprising: imprinting said primary and secondary emulsions respectively with cooperating images; developing said images; mordanting theI image of said secondary emulsion to receive a dye; applying a dye to said secondary emulsion; subjecting the film to a toning solution containing ferrie salts; and clearing said primary emulsion by subjecting the film to an iodide-containing solution. y

15. A method of producing a color positive from a' lm having an emulsion structure thereon of sufficient thickness to be divided-into inner and outer layer portions, comprising: printing complementary photographic images on said inner and outer portions oi said emulsion; developing said images; mordanting the image o! said outer portion for a basic dye; pplyin red basic dye to said outer portion; blue-toning said inner portion of said emulsion by Aapplicationthereto of a blue-toning solution containing ferric salts; and clearing said inner portion by subjecting the iilm to a solution of potassium 4iodide.

16. A method of producing acolor positive from a lm having an emulsion structure thereon of suiilcient thickness to be divided into inner and outer layer portions, comprising: printing.y

complementary photographic 'images on said inner and outer portions of said emulsion; developing said images; mordanting the image of said outer portion for a basic dye by use of a solution having potassium iodide as its principal constituent; arresting the action of the mordant by subjecting it to a bisulphite solution; applying red basic dye to said outer portion; blue-toning said inner portion lof said emulsion by application thereto of a blue-toning solution containing ferric salts; and clearing said inner portion by subjecting the illm to a solution of potassium iodide.

17. A method of producing a color positive from a lm having an emulsion structure thereon of suilicient thickness to be divided into inner and outer layerportions, comprising: printing complementary photographic images on said inner and outer portions of said emulsion; developing said images; mordanting the image of said outer portion for a basic dye; applying basic dye to said outer portion; toning said inner portion of said emulsion by application thereto of a toning solution containing ferrie salts; and clearing said inner portion by subjecting the iilm to a solution of potassium iodide.

18. A method of producing a color positive from a film, having an emulsion structure thereon of suiiicient thickness to be divided into inner and outer layer portions, comprising: printing complementary photographic images on said inner and outer portions of said emulsion; developing said images; mordanting the image of said outer portion for a basic dye by use of a solution having potassium iodide as its principal constituent; arresting the action of the mordant by subjecting it to a bisulphite solution; applying basic dye to said outer portion; toning said inner portion of said emulsion by application thereto of a toning solution containing ferrie salts; and clearing said inner portion by subjecting the lm to a solution of potassium iodide.

v19. A method of producing a color positive from a iilm having an emulsion structure thereon of suirlcient thickness to be divided into inner and outer layer portions, comprising: printing complementary photographic images on said inner and outer portions of said emulsion; imprinting a sound image simultaneously through both said inner andouter portions so that such sound image will be impressed in both inner and outer portions of said emulsion; developing said images; mordanting the image of said outer portion for a basic dye; applying red basi'c dye to said outer portion; blue-toning said inner portion of said emulsion by application thereto of a blue-toning solution containing ferric salts; and clearing said inner portion by subjecting the lm to a solution of potassium iodide.

j 20. The method of producing a color photograph which includes: producing two superposed images in a photographic emulsion; developing said images; coloring the outer of said images a certain color; toning the inner of said images a substantially complementary color; and clearing said images with a solution containing potassium iodide.

21. The step in color toning a photograph which consists of clearing said toned photograph with a solution containing potassium iodide.

' 22. A method of producing a. color positive from a illm having an emulsion structure thereon of suflicient thickness to be divided into inner and 'outer layer portions, including; printing superimposed complementary color value images in said inner and outer portions of said emulsion; developing said images; mordanting the outer image for a basic dye; applying a blue to green basic dye to said outer image; red toning said'inner image with a solution containing a uranium salt; and clearing 'saidinner image with a solution containing potassium iodide.

WILLIAM T. CRESPINEL.

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