US2358169A - Photographic printing material - Google Patents

Description

Patented Sept. 12, 1944 T PHOTOGRAPHIC PRINTING MATERIAL William J. Kridel, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application March 14, 1941, Serial No, 383,394

17 Claims.

This invention relates to photographic printing material and mor particularly to photographic material giving various degrees of contrast.

It is common practice to manufacture sensitive photographic emulsion of different kinds which give various degrees of contrast when submitted to the same treatment, such various degrees of contrast being obtained by well known technique in the manufacture of emulsions, such as by variation in the grain size. Although it is possible to bring about variation in contrast by suitable choice of development procedure (e. g. time or temperature variations) it is more useful to select the emulsion for the purpose of obtaining the desired contrast, as this allows of the use of standard times and temperatures of development which gives, among other things, the most convenient and simplest processing conditions, as well as a greater range of contrast (gradation). Thus, when making prints of a number of different emulsion which works soft. If, on the other hand, it is desired to print from a-negative with but little contrast, thelightwhichacts upon the emulsion which works soft is cut off by means of a filter permeable only to blue, and a normal picture is obtained by means of the emulsion which works hard.

variation of the above process involves the sensitization of the contrasty chloride emulsion negatives differing widely in their contrast one usually takes say three or four different sensitive photographic papers, each giving a different gradation, and selects therefrom the paper giving the most suitable gradation for each particular negative.

It has been suggested to coat over one another sensitive layers which work as differently as possible in gradations and which act differently under the action of the same kinds of light In this manner, a plurality 'of gradations are made available in a single element, and to alimited extent variations in contrast can be obtained by varying the exposure time. Such a multi-contrast element, however, leaves much to be desired.

It has also been suggested to employ two different emulsions (either coated in layers upon one another or mixed together in one layer) which give different gradations under the same conditions of development. Thus, an emulsion which works hard and is sensitive to blue (such as a' silver chloride emulsion) can be mixed with an emulsion which works soft and is sensitive to green (such as a spectrally sensitized silver bromide emulsion) to give a composite emulsion .capable of giving a plurality of contrasts. For example, if such a composite emulsion is exposed to light passing through a blue-green filter, the emulsion works normally'and is suitable for negatives of normal gradation. If, however, it is desired to print from anegative with strong contrasts, the light which acts upon the emulsion which works hard is cut off by means of a filter permeable only to,green,

and a normal picture is obtained by means of the instead of the softer bromide emulsion, to the green portion of the spectrum,

'I have now foundrthat advantageous results can be obtained by coating over one another two or more layers of silver halide emulsions of different contrast, the silver halide of the layers being of substantially the same, instead of different chemical composition, the layers being sensitive to different spectral regions. The image colors given by the two silver halides of substantially the same chemical composition can be more nearly alike than when different emulsions are employed. By using substantially the same silver halides rather than different ones, the time of development is more constant over the whole range of contrasts when the same developing solution is used; indeed the nature of the developing solution is of less importance, so that satisfactory results can be obtained with a wide variety of developing solutions. Moreover, if any addition (e. g. potassium bromide) is made to the developing solution the effect thereof will be more nearly the same over the whole range than when the emulsions involved are different.

It is, accordingly, an object of my invention to provide a photographic printing material which gives various degrees of contrast. A further object is to provide a process for preparing such materials. Other objects will become apparent of my invention.

hereinafter.

In accordance with one embodiment of my invention, I position on one side of a suitable support, such as of photographicpaper, of glass, of cellulose acetate or nitrate film, or of polyvinyl acetal resin film, a layer of silver chloride emulsion of one contrast (gamma) over another layer of silver chloride emulsion having a different contrast (gamma).

halide emulsion containing over of silver By the term silver chloride emulsion," wherever used herein, I mean a silver chloride based on the total silver halide. It is the practice sometimes to incorporate a small amount (several percent) of silver iodide or silver bromide in silver chloride emulsions, and such emulsions are included within the term of this embodiment I secure a difference in response to light of different wave lengths between the aforesaid two layers by spectrally (optically) sensitizing one of the layers with a sensitizing dye. It is known that the maximum sensitivity of silver chloride emulsions is at about 390 mu. and that the sensitivity falls away sharply toward the longer wave lengths, so that for practical purposes chloride emulsions have no useful sensitivity at wave lengths above 420 mu. In the present embodiment of my invention, I have found it advantageous to sensitize one of the chloride emulsions to a wave band between about 425 mu. and about 600 mu. and such wave band can have a maximum at about 470 mu., 530 mu. or 570 mu, but advantageously not higher. If maximum sensitivity at 530 mu. obtains, the printing material can be handled and processed under a safelight comprising light in the region from approximately 560' mu. upwards, i. e, an orange colored light. In the present embodiment of my. invention, the speed of the non-color sensitized emulsion to violet light (i. e. the light to which the emulsion is most sensitive) may be smaller or greater than (for example one-half to one and a. quarter or even two or three times) the speed of the colorsensitized emulsion to yellow light (minus blue light) and is also greater than (for example about two to about ten times) the speed of the color sensitized emulsion to the same violet light.

In the present embodiment of my invention the desired range of gradations can be obtained when making the exposures by using at one end of the range a filter transmitting light of a maximum of about 360 mu. (e. g. a Wratten No. 35 filter), but little useful light at wave lengths above about 440 mu., and at the other end of the range a filter of high transmission at about 530 mu. or longer but little useful light at wave lengths below about 480 mu. (e. g. a Wratten No. 5 filter).

According to another form of the present embodiment of my invention two silver chloride emulsion layers are employed each of which is spectrally sensitized to different wave bands. Advantageously the one emulsion is spectrally sensitized so as to have a maximum at about 460 mu. and the other is sensitized so as to have a maximum at about 530 mu. to 570 mu. -It is advantageous to employ a sensitizing dye which gives a sensitization which falls away sharply toward the longer wave lengths so that there is no useful sensitivity at about 600 mu. The dyes are advantageously chosen so that there is no, or only a little, useful sensitivity in both emulsions at the intermediate wave lengths between the sensitizing maxima of the dyes; In this form of the invention the speed of the first mentioned emulsion layer to blue light can be more or less (preferably between one-quarter and four times) than the speed of the second layer to yellow light (minus blue). Although the speeds of the two emulsions in the wavelength-range of their natural sensitivities are not highly important relative to the speeds of the emulsions at the sensitized maxima, it is nevertheless convenient that the emulsions should be so spectrally sensitized that the natural sensitivity remains relatively low; for example, one-fourth to one-tenth of the speeds at the sensitized maxima.

In this form of the invention it is best to obtain the desired range of gradation in making the exposure by using at one end of the range a filter transmitting light of a maximum of about 4'70 mu.. but little useful light at wave lengths below about 410 mu. and above about 500 mu., and at the other end of the range a filter transmitting light of a maximum of about the same as the sensitized maximum of the second mentioned emulsion, but little useful light at wave lengths below about 500 mu. The printing material prepared according to this form of the invention may be handled and processed under a safelight comprising light in the region from approximately 600 mu. upwards, i. e. orange or red light.

In the first of the above forms of my invention it is preferred to employ for the emulsion giving the higher gradation the one which has the sensitivity at the higher wave lengths. It is also preferred to make the speeds of the two emulsions about the same in the spectral regions employed for exposure purposes. The gradation of the emulsion giving the lower contrast can, for example, be between 0.8 and 1.8, while the gradation of the emulsion giving the higher contrast can be at least two and one-half times greater.

The following example will serve to illustrate the present embodiment of my invention:

Example I Two emulsion layers were coated upon a suitable photographic paper support. The two layers comprised respectively a low contrast silver chloride developing-out emulsion sensitized with 3- ethyl-5- (1-methyl-2 (1) -B naphthoxazolylidene) -rhodanine at a concentration of 100 mg. per 1000 grams of silver nitrate used in the preparation of the emulsion, and a high contrast silver chloride developing-out emulsion sensitized with 5 (2 ethyl-1-benzoxazolylidine-ethylidene)-3- ethyl rhodanine at the same concentration. If desired the concentrations of these dyes can be varied over a range of about 25 to 200 mg. In the coating of the paper the low contrast chloride emulsion is first coated on the paper in the range of normal thickness of paper coatings and above it is coated the high contrast chloride emulsion at about the same thickness. The filters which should be employed with a printing material prepared in this manner are the Wratten No. 34 to obtain low contrast and the Wratten No. 12 for high contrast. Mixtures of exposures employing these two filters will, of course, produce intermediate contrasts.

In accordance with a second embodiment of my invention I position on one side of a suitable support a layer of silver chloro-bromide developingout emulsion of one contrast over another layer of silver chloro-bromide developing-out emulsion having a different contrast. By the term silver chloro-bromide emulsion" wherever used herein I mean a silver halide emulsion containing over 10% and less than (but preferably over 30% and less than 70%) of silver chloride based on the total silver halide. It is desirable that the silver chloride content of the two emulsions should not differ by more than 25% and preferably not more than 10%. It is the practice sometimes to add a small amount of silver iodide to silver chloro-bromide emulsions and such emulsions are included within the terms of this embodiment ogtmy invention.

I have found hat the best results are obtained by using for the sensitive material in the present form of my invention, a silver chloro-bromide emulsion layer of relatively high gradation sensitized to the green, or yellow, or yellow-green, region of the spectrum, with a silver chloro-bromide emulsion layer of relatively low gradation but not spectrally sensitized. On such a material I print from negatives of high contrast by means of blue light, from negatives of medium contrast by means of white light (tungsten) or mixed blue and yellow to green light and from negatives of low contrast by means of suitable light in the minus blue part of the spectrum. In order to produce a sensitive material of the greatest convenience and simplicity we have found that the coated emulsions and the spectrally sensitizing dye should be so chosen that the speed of the non-spectrally sensitized blue-sensitive emulsion layer to blue light (i. e. the light to which the emulsion is most sensitive) should be at least 1.8 (and preferably at least twice) the speed of the spectrally (color) sensitized emulsion layer to the same blue light. The speed of the spectrally sensitized emulsion layer in the green to yellow should be not less than one-third and may be up to one and one-fourth or even two or three times the speed ofthe non-spectrally sensitized emulsion layer in the blue region. The gradation of the non-spectrally sensitized emulsion should be between 0.8, and 1.8, while the gradation of the spectrally sensitized emulsion layer in the yellow green region of the spectrum should be at least 2.5 times greater.

In accordance with a third embodiment of my invention I position on one side of a suitable support a layer of silver bromide emulsion of one contrast over another layer of silver bromide emulsion having a different contrast. The bromide emulsions of the present form of my invention advantageously should not contain any appreciable quantity of chloride, although it is possible to use up to of silver chloride based on the total weight of silver halide without markedly noticeable efiects. It is the practice sometimes to add a small amount of silver iodide to silver bromide emulsions and such emulsions are included within the terms of the present embodiment of my invention. In the present form of my invention both emulsions can be made more highly sensitive then when one or both of the emulsions are wholly silver chloride or contain an important proportion of silver chloride as in the case in the so-called chloro-bromide emulsions.

In one form of this third embodiment of my invention I employ one layer of asilver bromide emulsion of relatively high gradation sensitized to the green or yellow or yellow-green region of the spectrum, with a layer of a silver bromide emulsion of relatively low gradation but not spectrally .sensitized. On such a two-emulsion layer material I print from negatives of high contrast by means of blue light, from negatives of medium contrast by means of white light (tungsten) or mixed blue and yellow to green light, and from negatives of low contrast by means of suitable light in the minus blue part of the spectrum. In order to produce a sensitive photographic element of the greatest convenience and simplicity I have found that the coated emulsions and the spectrally sensitizing dye should be so chosen that the speed of the non-spectrally (non-color) sensitized emulsion to blue light (i. e. the light to which the emulsion is most sensitive) should be at least 1.8 (and preferably at least twice) the speed 01 the color sensitized emulsion to the same blue light. The speed of the spectrally sensitized emulsion in the green to yellow region should be between one-third and one and one quarter times the speed of the non-spectrally sensitized emulsion in the blue region. The gradation of the non-spectrally sensitized emulsion should be between 0.8 and 1.8 while the gradation of the spectrally sensitized emulsion in the yellow to green region of the spectrum should be at least 2.5 times greater.

The following example will serve to illustrate this third embodiment of my invention.

Example II cyanine iodide, a speed in the blue region of 2.0

' and a speed in the green of 5.6 and a gradation difierent color exposure lights.

of 5.4. This emulsion is used for the under layer. For the upper layer such an emulsion is prepared which gives a speed in the blue region of 5.4 and a gradation of 1.5. This two-emulsion layer material is exposed by tungsten light through negatives of low gamma through a Wratten No. 5 filter, through negatives of high gamma through a Wratten No; 47A filter and through negatives of medium gamma through no filter or through a Wratten K1 filter. An advantage of coating the emulsions in separate layers (two or more) as is done in accordance with any of the embodiments of m invention is that wandering (diffusing) of the sensitizing dyes from one layer to another can be fairly readily overcome. For example, any such tendency can be ofiset by coating a thin, intermediate, clear gelatin layer between the emulsion layers and incorporating in the intermediate layer substances which are capable of retarding diffusing of the sensitizing dyes, whereby any sensitizing dye which wanders into the layer will besubstantially prevented from passing through a layer into the next emulsion layer. Such an intermediate layer may also contain a filter dye to assist in obtaining the desired range of contrasts with Preferably the filter dye should be one that becomes decolorized in the processing baths. I

If there is any tendency for the sensitizing dye employed in one emulsion layer to Wander into the other emulsion layer it may be advisable to offset the effect produced thereby by using emulsions of more widely diiTering gradations. For example, the higher one may be increased to such an extent that it is at least 3.5 or even at least 4.5 times greater-than the gradation of the other em'ulsion. Usually the gradation of the optically sensitized emulsion giving the higher gradation will not be more than about 7 or 8.

Instead of coating the two emulsions in layers, the emulsions can be mixed together before applying to a'support. Such mixed emulsions have the advantage that a printing material can be produced therefrom with at least one less coating operation, than when superimposed layers of the two emulsions are employed. Moreover, from such mixed emulsions printing elements can be produced. the over all weight of which is less than that of an element produced with layers of emulsions. Such lighter weight elements are less brittle and have a lesser tendency to curl than the heavier layered elements.

Prepared in accordance with any of the em bodiments of my invention, I have found that the ratio of silver between the contrasty and soft emulsions is advantageously 1:1, i. e. the moles 'United States Patent 2,331,660, dated October 12,

1943), or substantially water-insoluble metal compounds, such as oxides and hydroxides, can

be incorporated in the emulsions alone or in conjunction with the above resins, or substantially water-insoluble metal salts of the above resins can be incorporated in the emulsions (see the copending application of Edward B. Knott, Serial No. 391,375, filed May 1, 1941, now United States Patent 2,336,260, dated December 7, 1943.

In practicing my invention, however, by far'the best results are obtained by using sensitizing dyes which are inherently non-diffusing. Non-diffusing sensitizing dyes which sensitize to the green are to be found in the thia-2'-cyanine, the benzothia-2-cyanine, the selena-2'-icyanine, the 2,2- cyanine, the thiazolo-2'-cyanine and the dibenzoxacarbocyanine classes of dyes. Non-diffusing dyes which sensitize to longer wavelengths are to be found in the dibenzothiacarbocyanine, the 5,5-dichlorothiacarbocyanine, the 5-chloroth.ia carbocyanine, the 5-chlorothiabenzothiacarbocyanine, the 5,5-dichloroselenacarbocyanine, the 5-chloroselenacarbocyanine and the 5-chloro-' selenabenzothiacarbocyanine classes of dyes. Non-diffusing sensitizing dyes are also to be found among the simple merocyanines, the merocarbocyanines and the merodicarbocyanines containing on the one hand-a 3-alkylrhodanine, a 3-arylrhodanine or a 2-diarylamino-4(5) -thiazolone nucleus and on the other hand a benzoxazole, a benzothiazole, a benzaselenazole, a naphthoxazole, a naphthothiazole, or a simple thiazole nucleus (1. e., a thiazole nucleus devoid of a fused-on aromatic ring, e. g. 4-methylthiazole and 4-phenylthiazole). Merocyanine dyes which contain a long chain organic group (e, g. a 3- heptyl-1-phenyl-2-thiohydantoin nucleus) and which are especially resistant to diffusion are described in the copending application of Leslie G. S. Brooker, Serial No. 321,730, filed March 1, 1940, now United States Patent 2,282,116, dated May 5, 1942.

The speeds referred to herein are measured by taking the exposure necessary to give a. density of 1.0. The contrasts are expressed as gamma or maximum gradient.

What I claim as myinvention and desire to be secured by Letters Patent of the United States is:

1. A photographic printing material for the production of images of difierentcontrast from black-and-white images, under the same conditions of development, comprising a layer of a the emulsion, and a silver bromide emulsion in which the" weight of silver bromide is at least90 per cent of the total silver halide in the emulsion, with anotherphotographic silver halide emulsion of the same species but having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being such that the two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to difierent spectral regions, both emulsions being free from dyes other than sensitizing dyes.

2. A photographic printing material for the production of images of difierent contrast from black-and-white images, under the same conditions of development, comprising a layer of a composite of a photographic silver halide emulsion having a contrast of 'at least about 0.8 selected from the group consisting of the three species: a silver chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from more than ,30 per cent to less than 70 per cent of the total silver halide in theemulsion, and a silver bromide emulsion in which the weight of silver bromide is at least 90 per cent of the total silver halide in the emulsion, with another photographic silver halide emulsion of the same species but having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being about 1:1, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, both emulsions being free from dyes other than sensitizing dyes.

3. A photographic printing material fo the production of'images of different contrast from black-and-white images, under the same conditions of development, comprising a layer of a composite of a photographic gelatino-silverhalide developing-out emulsion having a contrast I of at least about 0.8 selected from the group consisting of the three species: a silver 'chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halidein the emulsion, and a silver bromide emulsion in which the weight of silver bromide is at least 90 per cent of the total silver halide in the emulsion, with another photographic silver halide emulsion of the same species,

the second emulsion having a contrast at least- 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of the lower contrast and the emulsion of higher contrast being such that the two emulcomposite of a photographic silver halide emulsion having a contrast of at least about 0.8 selected from the group consisting of the three species: a silver chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from more than 30 per cent to less than per cent of the total silver halide in sions can be developed, under the same conditions of development, to maximum densities of the 1 same order, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to diiferent spectral regions, both emulsions being free from dyes other than sensitizing dyes.

4. photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a layer or a composite of a photographic gelatino-silverhalide developing-out emulsion having a contrast of at least about 0.8 selected, from the group consisting of the three species: a silver chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from. more than 30 per cent to less than '70 per cent of the total silver halide in the emulsion, and a silver bromide emulsion in which the weight of silver bromide is atleast 90 per center the total silver halide in the emulsion, with another photographic silver halide emulsion of thesame species, the second emulsion having a contrast at least 2.5 times as great as the contrast of the first production of images of diner contrast from black-and-white images,'und' ,th same'conditionsof development, comprising layer of a composite of a photographic gelatino-silverhalide developing-out emulsion having a contrast of at least about 0.8 selected from the group consisting of'th'e three species: a silver chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver-halide in the emulsion, asilver chlorobromide emulsion in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion, and a silver bromide emulsion in which the weight of silver bromide is at least 90 per cent of the total silver halide in the emulsion, with another photographic silver halide emulsion of the same species, the second emulsion having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being such that the two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, at least one ofthe emulsions being sensitized with asensitizing dye so that the emulsions are sensitive to 'difierent spectral regions, the speed of the emulsion of lower contrast to light to which the emulsion is inherently most sensitive being from about two to about ten times the speed of the emulsion of higher contrast to the same light, both'emulsions being free from dyes other than sensitizing dyes.

6. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a. layer of a composite of a photographic gelatino-silverhalide developing-out emulsion having a contrast of at least about 0.8 selected from the group consisting of the three species: a silver chloride emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from more than 30 per cent to less than '70 per cent of the total silver halide in the emulsion, and a silver bromide emulsion in which the weight of silver bromide is at least 90 per cent of the total silver halide in the emulsion, with another I having a contrast of'at least about 0.8 in which photographic silver halide emulsion of the same species, the second emulsion having a contrast at least 2.5 times as great as the contrast of the first emulsion, the'ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being about 1:1, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, the speed of the emulsion of lower contrast tolight to which the emulsion is inherently most sensitive being from about two to about ten times the speed of the emulsion of higher contrast to the same light, both emulsions being free from dyes other than sensitizing dyes.

7. A photographic printing material for. the production of images of difierent contrast from black-and-white images, under the same conditions of development, comprising a support bearing on one side a composite of a photographic gelatino-silver-chloride developing-out emulsion having a contrast of at least about 0.8 in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion with another photographic gelatino-silver-chloride developing-out emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion coated 8. A photographic printing material for the production of images of diiierent contrast from blaok-and-white images, under the same conditions of development, comprising a support bearing on one side a composite of a; photographic gelatino-silver-chloride developing-out emulsion the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chloride developing-out emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being about 1:1, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, both emulsions being free from dyes other than sensitizing dyes.

9. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a layer of a composite of a photographic gelatino-sllver-chloride developing-out emulsion having a'contrast of at least about-0.8 in which the weight of silver chloride is more than per cent of the total silver halide in the emulsion with another photographic gelatino-silver-chloride developing-out emulsion in whichthe weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion having a contrast at least 2.5

times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being such that the two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, the speed of the emulsion of lower contrast to violet light being from about two to about ten times the speed of the emulsion of higher contrast to the same light, both emulsions being free from dyes other than sensitizing dyes.

10. A photographic printing material for the production of images of difierent contrast from black-and-white images, under the same conditions of development, comprising a layer of a composite of a photographic gelatino-silver-chloride developing-out emulsion having a. contrast of at least about 0.8 in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion with another photographic gelatino-silver-chloride developing-out emulsion'in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion a of lower contrast and the emulsion of higher contrast being about 1:1, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, the speed of the emulsion of low contrast to violet light being from about two to about ten times the speed of the emulsion of higher contrast to the same light, both emulsions being free from dyes other than sensitizing dyes.

11. A photographic printing material for the production of images of diflerent contrast from black-and-white images, under the same conditions of development, comprising a support bearing on one side a composite of a photographic gelatino-silver-chloride developing-out emulsion having a contrast of at least about 0.8 in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chloride developing-out emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being such that the} two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, the emulsion of lower contrast being free from sensitizing dyes and the emulsion of higher contrast being sensitized with a sensitizing dye so as to have a maximum of spectral sensitivity at from about 470 mu. to about 530 mu., the speed of the emulsion of lower contrast to violet light being from about two to about ten times the speedof the emulsion of higher contrast to the same violet light, both'emulsions being free from dyes other than sensitizing dyes.-

12. A photographic printing material for the production of images of difierent contrast from black-and-white images, under the same conditions of development, comprising a support bearing on one side a composite :of a photographic gelatino-silver-chloride developing-out emulsion having a contrast of at least about 0.8 in which the weight of silver chloride is more than per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chloride developing-out emulsion in which the weight of silver chloride is more than 90 per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being about 1:1, the emulsion of lower contrast being free from sensitizing dyes and the emulsion of higher contrast being sensitized with a sensitizing dye so as to have a maximum of spectral sensitivity at from about 470 mu. to about 530 mu., the speed of the emulsion of lower contrast to violet light being from about two to about ten times the speed of the emulsion of higher contrast to the same violet light, both emulsions being free from dyes other than sensitizing dyes.

13. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a support bearing on one side a composite of a photographic gelatino silver chlorobromide developing -'out emulsion having a contrast of at least about 0.8 in which the weight of silver chloride is from more than 30 per cent to less than '70 per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chlorobromide developing-out emulsion in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5

times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher cohtrast being such that the two emulsionscan be developed, under'the same conditions of development, to maximum densities of the same order, at least one of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to difierent spectral regions, both emul- Zions being free from dyes other than sensitizing yes.

14. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a support hearing on one side a composite of a photographic gelatino silver chlorobromide developing out emulsion having contrast of at least about 0.8 in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chlorobromide developing-out emulsion in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5 times as great as the contrast of the first emulsion, the ratio of silver between the emulsion of lower contrast and the emulsion of higher contrast being about 1:1, at least two of the emulsions being sensitized with a sensitizing dye so that the emulsions are sensitive to different spectral regions, both emulsions being free from dyes other than sensitizing dyes.

15. A photographic printing material for the production of images of difierent contrast from black-and-white images, under the same conditions of development, comprising a support bearing on one side a composite of a photographic gelatino silver chlorobromide developing out emulsion having a contrast of at least 0.8 in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion and another photographic gelatino-silver-chlorobromide developing-out emulsion in which the weight of silver chloride is from more than 30 per cent to less silver between the emulsion of lower contrast and the emulsion of higher contrast being such that the two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, the emulsion of lower contrast being free from sensitizing dyes and the emulsion of higher contrast being sensi tized with a sensitizing dye so as to have a maxi- -mum of spectral sensitivity in the yellow-green region of the spectrum, the speed of the emulsion of lower contrast to blue light being at least about 1.8 times the speed of the emulsion of higher contrast to the same blue light, both emulsions being free from dyes other than sensitizing dyes.

16. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a support hearing on one side a composite of a photographic gelatino silver chlorobromide developing out emulsion having a contrast of at least about 0.8 in which the weight of silver chloride is from more than 30 per cent to less than '70 per cent of the total silver halide in the emulsion and another photographic gelatinol-silver-chlorobro- 40 mide developing-out emulsion in which the weight of silver chloride is from more than 30 per cent to less than per cent of the total silver halide in the emulsion coated upon the first emulsion and having a contrast at least 2.5 40

times as great as the contrast of the first emulsion; the ratio of silver between the emulsion of higher contrast being about 1:1, the emulsion of lower contrast being free from sensitizing dyes and'the emulsion of higher contrast being-sensitized with a sensitizing dye so as to have a maximuin of spectral sensitivity in the yellow-green region of the spectrum, the speed of the emulsion of lower contrast to blue light being at least about 1.8 times the speed of the emulsion of higher contrast to the same blue light, both emulsions being free from dyes other than sensitizing dyes.

1'7. A photographic printing material for the production of images of different contrast from black-and-white images, under the same conditions of development, comprising a layer of a composite of a photographic gelatino-silverhalide developing-out emulsion having a contrast of at least about 0.8 selected from the group consisting of the three species: a silver chloride emulsion in which the weight of silver chloride is more than per cent of the total silver halide in the emulsion, a silver chlorobromide emulsion in which the weight of silver chloride is from more than 30 per cent to less than 70 per cent of the total silver halide in the emulsion, and a silver bromide emulsion in which the weight of silver bromide is at least 90 per cent of the total silver halide in the emulsion, with another photo'graphic silver halide emulsion of the same species, the second emulsion having a contrast at least 2.5times as great as the contrast of the first emulsion, the .ratio of silver between the emulsion of higher contrast being such that the two emulsions can be developed, under the same conditions of development, to maximum densities of the same order, the emulsion of lower contrast being free from sensitizing dyes and the emulsion of higher contrast being sensitized with a. sensitizing dye so as to have a maximum of spectral sensitivity at a wavelength longer than the maximum of spectral sensitivity of the emulsion of higher contrast, the speed of the lower contrast emulsion to light to which it is inherently most sensitive being substantially greater than the speed of the emulsion of higher contrast to the same light, both emulsions being free from dyes other than sensitizing dyes.

WILLIAM J. KRIDEL.