DE1020865B - Process for making direct photographic positives - Google Patents

Description

GERMAN

The invention relates to a method of making direct photographic positives.

It is known to produce direct positives by the silver salt diffusion process by a photographic layer serving to receive the object in contact with a positive image absorbing layer and distributing the developer between the layers.

Compared to this known method, the method according to the invention is characterized in that that between two superimposed layers, one of which is transparent, or both layers are transparent, in the presence of developers and fixing agents a liquid photosensitive Halide silver emulsion is distributed until a photosensitive layer is formed, and that this photosensitive layer Material is exposed imagewise in the case of superimposed layers.

In the method, an arrangement can be used which has little or no shielding from the surrounding area Requires light and which consists of two superimposed sheets and a container in which the photosensitive composition to be distributed between the sheets is in the presence of a developer. Here, the developer can be held in various ways, for example, the developer can be dispersed in one of the sheets when dry. The mass is inside the exposure chamber a camera spread between the two sheets to form a photosensitive layer or to form a photolayer when it passes through one of the two sheets or after separation the sheet is exposed contains a latent image from which a usable print can be made without further handling or treatment can be established.

Here, according to the invention, the liquid emulsion can be emptied from a light-tight container Halide silver developing agent be mixed with the halide silver emulsion before spreading, wherein the alkali of the developer and / or the halosilver solvent prior to distribution in one of the There may be superimposed layers and a silver precipitant prior to spreading with the Halide silver emulsion is mixed.

Further, in the present invention, an alkali-soluble inhibitor layer can be used which is the photosensitive Layer separates from the corresponding layer of the superimposed layers. Furthermore, that The alkali and the developer are applied on opposite sides of the inhibitor layer, the alkali being able to dissolve them in the presence of the photosensitive layer.

In the drawings is

Fig. 1 is a cross-sectional view of a film structure for the execution method of manufacture
direct photographic positives

Applicant:

International Polaroid Corporation,
Jersey, NJ (V. St. A.)

Representative:
Dr.-Ing. H. Ruschke, Berlin-Friedenau, Lauterstr. 37,

and Dipl.-Ing. K. Grentzenberg, Munich 27,
^X 5 patent attorneys

Claimed priority:
V. St. v. America March 29 and April 1, 1955

Edwin Herbert Land, Cambridge, Mass.,
and Otto Edward Wolff, Weston, Mass. (V. St. Α.),
have been named as inventors

tion of the aforementioned silver transfer reversal process;

Figures 2 and 3 are sections of the film structure shown in Figure 1 in use;

Fig. 4 is a sectional view of a film structure for carrying out the aforesaid silver transfer reversal process;

Fig. 5 is a sectional view of the film structure shown in Fig. 4 in use;

Fig. 6 is a partially broken enlarged section of a camera used for treatment of the film structure shown in Fig. 4 and in the other subsequent figures;

Figure 7 is a section on line 7-7 of Figure 6; Figs. 8, 9, 10, 11, 12 and 13 are sections of others Film assemblies for carrying out silver transfer reversal processes.

The film structure shown in Fig. 1 consists of a photo-layer sheet with a carrier 10 and a silver halide gelatin layer 12, further comprising an image receiving sheet with a support 14 and a silver receiving layer 16 and a container 18 containing an aqueous alkaline solution 20 of a Incorporates silver halide developer and a silver halide solvent. Fig. 2 shows the film structure

709 809/303

3 4

after distributing the solution 20 between the sheets, tung mass formed. The treatment mass contains the spreading being done, for example, in addition to the silver halide developer and the that the film build-up between two pressure rollers is preceded by silver halide solvents silver precipitants like them is pushed. Immediately after distribution or in the 932,344 patent. The Silberauf spreading the solution 20 is the photo layer 12 ^ 5 taking layer 16 is omitted. After finishing agent the lens of a 'camera exposed. The carrier 14 will collect the treatment is desirable that the exposure soon after the application of the layer of treatment material in which a The treatment liquid is divided so that a positive is formed from the photosensitive silver desensitization stripped of the photosensitive material halide layer 12 and its support 10, is avoided by the treatment solution, d. h., io In a further modification of the in Fig. 1 dardie Exposure should be 1 second or less after the set up of the film is the outer surface of the Distributing the treatment liquid take place. Inner carrier 14 of the image-receiving sheet, which in this half of a predetermined period of time reduced trap is transparent, verdann with an optical grid the solution 20 see the silver halide, for example with a lenticular or Layer 12 to silver to form a negative and 15 to a color screen for additive dyes. After this continues with the unreduced silver halide distributing the mass between the inner surface of the in order to form a complex silver salt which is through the image receiving sheet and the photo layer 12 the solution layer is exposed through the raster to the difround photo layer through the layer 16, dated, in which it is reduced to silver and the resulting image, which is either in the silver-on-positive forms. Finally, the layer 12 is increased 20 layer 16 or in the solvent layer 20, together with the solution layer (Fig. 3) when this layer contains silver precipitant Layer 16 stripped to use the positive. becomes automatic with the grid through which the In contrast to this, the image can also be viewed together, aligned, Set print both the negative of layer 12, Figs. 4 and 8 to 13 show film structures,

as well as the positive of layer 16, without 25 for which the aforementioned method according to Art that stripping occurs. of the silver transfer reversal process

The mass 20 contains a silver halide developing is.

ler, for example hydroquinone, a silver halide- The film structures described below

solvent, for example sodium thiosulphate, and are made up of two sheets and one part of two film-forming substance, for example a water-soluble at least one of the constituents of a silver halide Polymer, e.g. B. a plastic, starch mass between these sheets in the presence of or gum or an insoluble, emulsifiable oil, reagents to be spread, the Bedas the solution has a viscosity of 100 to 200,000 cP components for carrying out the silver transfer at 20 ° C granted. Reversal process from a silver halide

An important area of use for the invention is in and from a silver halide solvent rapid photography, in which the regression of the exist. These reagents are in practice latent image should be shortened. Experience in many places of the film structure, so that the corresponding high quality prints are only then applied to the Reverse transfer processes act in the above silver halide composition when the composition was mentioned Way has been divided from silver halide emulsions with 40. In other words: the developer Sensitivities over 100 A.S.A. obtain. and / or the solvent will be from the silver

halide mass kept or separated. to-

For example 1 together with the silver halide mass in ineffective

kept in the same condition. For example, the

In a specific example of the above 45 developer and / or solvent in dry

In the process, the gelatin silver halide layer 12 is state in one or both sheets an iodobromide gelatin emulsion of medium light emulsion to be dispersed so as to be compatible with silver halide sensitivity; the silver receiving layer 16 is 1 to 8 μ mass only come into contact after the distribution.

thick and contains silver precipitants. A typical formula Or it can be an alkaline developer with the

the treatment mass is as follows: 50 silver halide mass mixed and in a non-

W _ater _ 1860 ecm alkaline environment until it spreads

Sodium Carboxymethyizeiluose ''.'. ^{Will hold} 93.0 g, which is done in the presence of an alkali,

Sodium sulfite '78 0 ε that dry on one sheet or on both sheets

Sodium hydroxide 54 6 ^{a is} dispersed. Part of the silver halide mass and

Sodium thiosulphate 14J5 g ⁵⁵ ^ ^er various reagents or the whole mass

Hydroquinone 52 0 g can be in one chamber or in several chambers

be accommodated by one or more

Shorter time than 1 second after the containers are completed. For example, two Distributing the mass 20 will be the silver halide chambers that separate the silver layer 12 exposed. Then the silver halide 60 halide mass and one component or more layer 12 and the silver receiving layer 16 in over-ingredients that are necessary to a superimposed position with the intervening reducing environment to create. It can too Mass 20 can be provided for a period of 40 to 120 seconds which separate the two chambers keep. At the end of this time the silver halide will contain silver halide components, for example layer together with the mass 20 of the silver 65 a salt with silver cations and a salt with a shark-receiving layer 16 stripped off, so that a positive genidanions, which only after their mixing, a light-high quality is visible. form sensitive mass. A silver precipitant can In a modification of that shown in Fig. 1 in a sheet in which the transfer image to In the film structure, the positive will not form in the silver, be dispersed or can be with the silver receiving layer, but are mixed in the layer of the hand- 70 halide compound if the excess

5 6

Wear pattern in the light-sensitive layer itself, for example, gelatine, agar, egg white, casein, colozu form is. The arrangement of the chemical substances dium, a cellulose substance such as carboxylmethylcellu can so within a film loose according to the invention, a vinyl polymer, for example poly

structure at will according to the numerous vinyl alcohol, or a linear polyamide, for example

Needs to be changed. 5 wise polyhexamethylene adipamide (6.6- »nylon«) di-

Usually it is desired that the exposure be blocked. Examples of certain shapes

immediately after distribution, for example internal emulsion, for this purpose

half a second after distributing, so are suitable, are described in T.T.Baker,

a desensitization of the photosensitive mate- Photographic Emulsion Technique, American Photo-

rials is avoided by the developer. Should ever- io Graphic Publishing Company, Boston, 1948,

but a short delay between distributing Chapter IV.

and the exposure of the silver halide mass. The developer is alkali-active, ie it is only desirable, so the development of, for example, an alkaline solution can be active, so that in the absence of one it can be delayed by the fact that between the light-alkali there is no development effect on the Silver sensitive layer and one of the ingredients that has halide emulsion in the non-alkaline environment created by container 124 necessary to form a reducing environment. If a temporary inhibitory layer is created, examples of this type are pyrogallol, hydro, for example, an alkali-soluble layer which is divided into quinone, metol, amidol, p-aminophenol and glycine. Presence of the reagents after a predetermined period. An antioxidant for the developer can delay dissolving. 20 can be added. Examples are sodium

The film structure shown in FIG. 4 consists of sulfite carried by the layer 126 , or two sheets 120 and 122, with their inner surfaces ascorbic acid contained in the container 124 .
In one embodiment, the silver receiving surfaces will either lie close to one another or be in a layer made of an organic plastic carrier when they come into contact with one another. On the sheet 120 , for example, sodium carboxymethyl cellulose is attached, here a container 124 , which puts a predetermined amount into which an aqueous solution is stirred, amount of a non-alkaline aqueous mass 128 made up of a silver halide solvent, which contributes a silver halide salt and a silver, for example sodium thiosulphate contains a silver precipitated halide developer which is only active in an alkali agent, for example one or more zinc or cadmium solution. The inner surface of the sheet 30 and lead sulfides and solenides, and made of an alkali, 120 is coated with a silver receiving layer 126 - e.g. B. a carbonate such as sodium carbonate, one in which an alkali, a silver halide solution borate such as borax, or a phosphate such as dimittel and a silver precipitant are dispersed. In the case of basic sodium phosphate, there is.
Compressing the container 124 by entgegen- As can be seen, the alkali used herein are set acting pressure forces the mass 35 128 relatively weak. Such weak alkali released in the frangible mouth 130 must be used when the alkali is dispersed on a sheet in a dry state in that it is distributed between sheets 120 and 122 and forms a photosensitive layer 132 (Fig. 5) . especially when the alkali takes in the presence of this layer when it is present immediately after its silver halide solvent. If production were to be exposed, a latent image would be produced from a strong alkali, for example a hydroxide, such as that of a positive in layer 126 in the following manner sodium hydroxide, in this case produced: That would be produced by the alkali from the layer the alkali, unless a distribution of the 126 activated treatment liquid coming from the container 124 immediately after the developer reduces the penetration of the alkali in the layer 132 into the layer 126 , to borrowed silver halide to silver, while the silver 45 the Dispersion of the inner surface of the web 122 or halide solvents from the layer 126 would have to react with the unreduced silver halide in a container separate from the developer in order to form plexus silver salts which are kept in the layer 126 in the manner described below.

diffuse where they are not exhausted in the presence of the. The substances from which the parts of the silver halide developer shown in FIG. 4 and of the silver precipitating agent 50 are put together can thus be reduced to silver. After a pre-established that the binding forces between a certain time after the distribution of the mass 128, mass 128 and layer 126 are less than that, the sheet 122 together with the layer 132 binding forces between mass 128 and sheet 122, from which sheet 120 is stripped in order to make the layer 126 in this arrangement so that the imaged print or the positive is visible. 55 Strip the layer 132 from the layer 126 at the end Under certain circumstances, at the end of this a predetermined treatment time can be facilitated. Time the positive can be used without stripping. One of the sheets, for example sheet 120, may consist of paper, depending on the particular one, of which at least one peculiarity of the material used, such as surface with a suitable material, is known in the art. 60 for example a hardened gelatin or with in

In one form, the mass 128, which is a baryte containing gelatin, has been coated.

is so fluid under spatial conditions that it can be made of glass or

can be easily distributed, produced in that there are a plastic, for example cellulose

the aqueous solution of a silver halide developer nitrate, or from an organic acidic cellulose

in a ripened light-sensitive silver halide ester, for example cellulose acetate, cellulose triacetate,

sion is stirred. Cellulose propionate, cellulose butyrate, cellulose acetate

In such an emulsion, a silver propionate or cellulose acetate butyrate can be used. Does the

halide or several silver halides, with sheet 120 made of such a plastic,

for example silver chloride, silver bromite and silver - thus good adhesion between sheet and layer

iodide, in an appropriate protective colloid, examples will be 70,132 safely reached the arch example,

7 8

a mixture of gelatine and cellulose nitrate, thoroughly dried with heating. The movie is about. One or both of the sheets was built through between two steel rollers to allow exposure and drawing, and the resulting photosensitive layer latent image would be formed in layer 132 if the sheets were held one on top of the other within a second of being made will. 5 position exposed. The structure shown in FIG. 4 can then be stacked and used in light before its duration of 120 seconds, since these were then separated to form the photosensitive positive material carried in the layer 126 by the structure to make visible, material is light-tight and airtight from- The film structure shown in Fig. 4 has in the

closed container 124 is located. In one embodiment, this container comprises a container which consists of a mass, which consists of a silver halide salt and a section of a three-layer sheet material which consists of an alkaline-active silver halide developer and has a single fold. The outer layer also serves as a layer that carries an alkali, a silver backing or carrier and consists of a thin, halide solvent and a silver precipitating agent, relatively cheap tough material, preferably 15 These substances can be applied as desired on one of the wise paper , like Kraft paper. The intermediate sheet, distributed or stored in the container, consists of a layer which is essentially vapor-proof, provided that the liquid-impermeable material present in the container, for example silver halide salts, is out of contact with the silver of a metal foil such as silver, lead or halide developers are held and that the nickel foil. 20 alkali-active silver halide developers except

The inner layer consists of a thermo-agitation with which alkali is kept. No plastic or thermosetting plastic, for example silver halide solvent, is required if, if desired, a polyvinyl acetate such as polyvinyl butyral, according to only a latent image in layer 132, or polyvinyl formal, which is to be wrapped around the container contents, i.e. does not protect any silver transfer contamination. Particularly satisfactory 25 reversal processes are to be carried out is a mass consisting of approximately 60 to 70 weight. Another embodiment of the invention is shown in FIG

percent polyvinyl butyral, approximately 10 to 23 Ge Fig. 8, in which the film structure is composed of one percent by weight nitrocellulose and approximately 5 percent by weight container 166 containing a predetermined amount of one percent by weight dibutyl sebacate. Contains silver halide mass 168 , from a sheet at opposite end portions of the container 30 170, which are coated with a treatment layer 172 , the two folds of the inner layer is by one, and consists of a sheet 174 , which with the action of heat and pressure Silver receiving layer 176 is coated. The bound. Those two portions of the two treatment layer 172 contains a silver halide fold which delimits the mouth 130 , is developer and a silver halide solvent. Those of an adhesive strip connected to one another, the so 35 silver receiving layer 176 contains an alkali, so formed that the connecting forces between, for example, sodium hydroxide, and a silver precipitation adhesive strip and inner layer are smaller than the medium, for example colloidal heavy metals, metal cohesive forces between the end sections of the sulfide and selenides, thiooxylates and thioacetamides, inner layer that are glued together. A pacifying strip which is dispersed in an inorganic carrier can, for example, consist of a silica-like masthen made of ethyl cellulose or a mixture of material, such as a silica airgel. Ethyl cellulose and paraffin, the mixture min- The silver halide developer, the silver halide

Contains at least 50 percent by weight ethyl cellulose. Solvent and the alkali of the layer 172 are. Since the binding forces between the sections bordering the mouth similarly to the corresponding parts of the film structure are smaller than the binding forces of FIG. mass 168 between layers 172 and 176 is formed by the action of opposing pressure, takes a latent image, emptied from the container mouth, when it is exposed to the container contents immediately after its origin on the container. a positive occurs spontaneously in layer 176

50 wraps.

Example 2 ^ ^{he 'n} Fig. 9 modified film structure consists of

a container 178 which is in a predetermined

In a particular form of containing a mass 180 in FIGS. 4 and 5 amount of a silver depicted film structure, the mass 128 was DA halide and a Silberfällmittel is produced by that 10 cc of a Jodbromidgelatine- 55 further from an arc 182 , which is coated with an emulsion of medium photosensitivity on liquid treatment layer 184 , which has been heated to a silver state and stirred into a solution of 0.19 g of halide developer and a silver halide solution amidol in 1 ecm of water. Contains about medium, and the _pH value of a determined-0.7 cc of the resulting mixture were in the loading of the layer 185, the injected an alkali, such as a container 124 with a syringe. The carbonate such as sodium carbonate, a borate such as layer 126 was made by receiving a silver borax or a phosphate such as sodium dibasic sodium receiving layer containing a silver precipitating agent of the above phosphate, and also consists of a sheet , was treated; this on 186, which spreads the mass on the surface of the layer on a sheet of baryta-supported layer 184. The mass 180 can, for example, be prepared for a period of about 20 seconds in a 65 by immersing a silver precipitating agent, aqueous solution containing 4.6 percent by weight z. B. one or more zinc, cadmium and lead sodium carbonate, 5.7 percent by weight sodium sulfides and selenides, sulfite and 3.6 percent by weight sodium thiosulfate in a silver halide emulsion, or in connection with the embodiment according to FIG. The excess solution was shaped of the type described. With the help of a stirring rod it is wiped off and the arch 70 is formed of the container 178 by means of oppositely arranged

Directed compressive forces, the mass 180 is released and spreads between the arches. As a result, as shown in FIG. 10, a Photosensitive layer 188 is formed, which after its exposure takes up a latent image from which by Silver transfer and reversal a positive is formed in situ.

If a product according to the invention is to be stored for a longer period of time, it is often desirable to separate the constituents of the silver halide composition from one another until use. The one in Fig. 11 Film construction shown is intended for such longer storage. The film structure has one Container 190, which is divided into two chambers 192 and 194, which contain components, which according to when mixed together form a photosensitive mass of silver halide. For example, the chamber contains 192 a salt with silver cations, for example silver nitrate, while chamber 194 is a salt with halide anions, for example sodium chloride, sodium bromide or sodium iodide or a mixture of these Contains substances. The arches between which the contents of chambers 192 and 194 are to be spread out, are similar in all respects to the sheets present in the film construction of FIG. 8 and are also with denoted by the corresponding reference numerals. Is the container 190 by means of oppositely directed When compressive forces are deformed, the contents of chambers 192 and 194 are expanded between the sheets or dispersed, the contents reacting to form a silver-sensitive silver halide layer form.

After exposure, this layer contains a latent image that can be seen in the presence of the treatment layer 172 a positive is formed in the silver receiving layer 176.

As a modification of the film structure shown in FIG. 11, one chamber of the container 190 contain a photosensitive composition or the one component of a photosensitive composition, while the other chamber of the container 190 is a treatment compound or one component of a treatment compound can carry, while the remaining components of the photosensitive composition and the Treatment mass in layers 172 and 176 are distributed. As a further modification, the container 190 but also have only one chamber which contains one component of a photosensitive mass, for example a salt with halide anions, while the other components of the photosensitive Mass, for example the constituents with a salt of silver cations, in the layer 172 or 176 to be distributed.

Is a short delay between the spreading and the exposure of the silver halide mass if desired, the action of the silver shark ogenide developer on the silver halide mass can be used be delayed. The film structure shown in Fig. 12 enables such a delay. Of the The structure consists of a sheet 196 coated with a silver receiving layer 198 and of a Distribution and stripping sheet 200. Between the sheets there is an alkali-soluble layer 202, furthermore a container 204 having a composition 206 containing a silver halide salt and a silver halide developer and a container 208 having a composition 210 containing an alkali and a silver halide solvent. The mass 206 is spread between layer 202 and layer 200, while the mass 210 is spread between layer 202 and layer 198. The layer 202 consists of, for example a material that dissolves or becomes permeable when dissolved. A material that is in a Rapidly dissolving alkaline solution is cellulose acetate hydrogen phthalate. When the containers 204 and 208 are simultaneously deformed by opposing pressure forces, they give their content free, which forms a photosensitive layer that has to be exposed shortly after its production, ίο and which forms a treatment layer that connects to the photosensitive layer after dissolving the layer 202 comes into contact.

The film structure shown in FIG. 13 shows a modified two-chamber container which enables that the silver halide mass with some of the treatment substances or with all treatment substances can be mixed before spreading or spreading. Here the mixing switches on within the container Vortex formation among the materials contained in the container prior to spreading or spreading the end. This container 212 is divided into two chambers 214 and 216, which are connected via a mouth closed by a frangible seal 218. The container 216 has an outlet

^a 5 mouth which is closed by a frangible seal 220. In the illustrated embodiment, chamber 214 contains a silver halide composition and an alkaline silver halide developer, while chamber 216 contains an alkali and a silver halide solvent. If opposing compressive forces are applied to the container 214 but not to the container 216, for example when the container 214 is advanced in front of the container 216 between two pressure parts, the frangible seal 218 is broken and the contents of the two chambers are mixed . Then, when the chamber 216 is advanced between the two pressure parts, the continued application of the pressure forces causes the mixed contents to break the seal 220 and the contents to be distributed between two sheets 222 and 224, one sheet with a Silver receiving layer 226 is coated. Immediately after spreading, the resulting photosensitive layer is exposed to light to produce a latent image from which a positive in the silver receiving layer 226 is spontaneously produced. While the production of black and white images or images consisting of silver or a dye or mixture of dyes is a preferred method, the invention can also be used to form color positives by producing images that are not neutral in appearance , but have, for example, a brown shade or a sepia shade.

Albeit the production of a positive image as the result of the transfer of the image-forming components specified from a photosensitive layer on a layer of an image receiving material has been, the invention also includes the proposals in which a positive in the photosensitive Layer itself is formed. For example, the positive layer can be a reversible silver halide emulsion, such as a polarized silver halide emulsion, or a special mixture of an emulsion and a silver precipitating agent contain a diazo salt.

Preferably, but not necessarily, the developer for the photosensitive material is included in the Treatment mass introduced dissolved. The developer

709 809/303

but can also be stored in any layer of the film structure and is after production of the overall layer structure when the layer of treatment liquid between the two Layers of the structure is activated.

Embodiments of the invention in which a lens-like grid is used are shown in the illustration these lenses on the outer surface of a film structure, but the design and arrangement also be taken so that the lens side of the grid inward of the outer surface of the layer structure lies. In this embodiment, a layer is preferably used between the lenticular lens and the photo layer arranged whose refractive index differs from the refractive index of the material from which the Lens grid is made. The refractive index of the last-mentioned layer determines whether the lenses for the grid must have a concave or convex shape, seen from the exposure side of the film structure the end. This design is particularly suitable for processes that use a treatment liquid use with a silver precipitant. In certain cases, lens grids can also be used, which have appropriate lenses or small lens particles on their two outer surfaces.

In the invention, a liquid treatment mass is used, which is the grid and the light-sensitive Layer firmly together in a certain orientation during exposure and treatment connects and maintains this alignment indefinitely. This practice enables raster treatment with conventional photographic material, so that no specially designed photo elements are required are. In addition, the practices shown here are for the production of negative and positive images suitable.

Since changes in the process can be made without departing from the scope of the invention, all descriptions and representations are not to be assessed in a limiting sense, but rather are only to be regarded as examples.

The numerous details described serve to facilitate the reworking of the invention, However, protection is only sought for that which forms the subject of the claims. 45

Claims (6)

Patent claims: 1. A method for producing direct photographic positives, characterized in that between two superimposed layers !, one of which is transparent, or both Layers are transparent in the presence of developer and one or more substances Substances containing silver salt solvents which participate in image formation, one liquid light-sensitive silver halide emulsion is spread until a light-sensitive layer arises, and that this photosensitive material is exposed imagewise when layers are superimposed will. 2. The method according to claim 1, characterized in that the liquid photosensitive emulsion is emptied from a light-tight container. 3. The method according to claim 1 and 2, characterized in that the halogen silver developer substance mixed with the silver halide emulsion before spreading. 4. Process according to claims 1 to 3, characterized in that the alkali of the developer and / or the silver halide solvent prior to spreading in the one of the superimposed Layers is in place. 5. The method according to claims 1 to 4, characterized in that a silver precipitant before mixed with the silver halide emulsion after spreading. 6. The method according to claims 1 to 5, characterized in that an alkali-soluble Inhibiting layer is used, which separates the photosensitive layer from the associated layer of the superimposed layers separates that the alkali and the developer substance on opposite one another Sides of the inhibitor layer are applied and that the alkali in the presence of the photosensitive layer to dissolve the inhibitor layer able. Documents considered: German Patent No. 940 505; U.S. Patent Nos. 2,543,181, 2,563,342,030. 1 sheet of drawings 709809/303 12.57