US2040575A - Method for the production of color cinematograph films - Google Patents

Description

y 2 I J. E. THORNTON 2,040,575

METHOD FOR THE PRODUCTION OF COLOR CINEMATOGRAPH FILMS Filed March 51, 1934 3 Sheets-Sheet 1.

INVENTOR 12, 1936- J. E. THORNTON 2,040,575

KETHOD'FCR THE PRODUCTION OF COLOR CINEMATOGRAPH FILMS Filed March 31, 1934 3 Sheets-Sheet 2 3 12- 234 Scnsihzed FI/m 1" Y BeFore Exposure 2) w v r E@ ,V /A\ 5;

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Patented May 1 2, 1936 LIETHOD FOR THE PRODUCTION OF COLOR CINEMATOGRAPH FILMS John Edward Thornton, Jersey, Channel Isles Application March 31, 1934, Serial No. 718,440 In Great Britain April 5, 1933 3 Claims;

This invention relates to cinematographic films with sound and picture records in parallel rows, and provides means whereby such records, first formed in black silver, can be changed or colored so that the picture records may be relief colloid images in one or more colors and the sound record be a relief colloid record in a difierent color, or black, the two records being formed simultaneously in separate rows, at the same operation or process, by applying to the black silver images of the two records a dry plaster of soluble colloid having stripes of differently colored colloid, or stripes of colored colloid and black colloid, followed by chemical action of a bleaching and hardening bath and other treatment.

Although the invention is designed more particularly for use in the production of multi-color pictures with sound on the same film, it can also be employed in the production of monochrome pictures.

The main feature of the invention consists in the means, method, and process for changing the images from black to color, and for producing dif- 2-3 ferential coloring of the sound record and of the picture-records, both of which are formed parallel with each other upon the same film strip.

Throughout the following specification and claims the term color is used in its broadest 3H sense as embracing any color including black.

The invention is applicable to films of the subtractive type, either in monochrome form, or in multi-color form of two, three, or four colors; and also to film-constructions in which the colorcomponent images are all upon one face of a single-ply film, or upon two opposite outer faces of a single-ply film, or enclosed and protected between the supports of a two-ply cemented film. According to the invention acincmatograph strip of positive images is produced by printing through a negative strip on to a positive strip of the ordinary type sensitized with gelatino-silver emulsion, then the film is developed fixed and washed, all in the usual manner, resulting in a strip having a series of positive images of metallic (or black) silver embedded in the gelatine and with the broad face of each image turned towards the outer face of the film and with the point or apex of each image turned towards the cellulose filmsupport.

The image of the sound record is printed on the positive film alongside and in the margin of the picture records, and such imageis developed and treated simultaneously with the picture 55 records n th same manner, forming a sound image of metallic silver also embedded in the gelatine. Although it is usual to have only one sound track, the invention can be applied to films havingtwo or more sound records in different margins.

After development both kinds of records are in non-relief and non-colored, and are of metallic silver similar to an ordinary monochrome silverprint; and the method of their production up to this stage follows the standard practice usual for producing the ordinary black and white pictures.

One necessary condition of the invention (not required for ordinary films) is that the gelatine layer in which these metallic silver records are embedded must be sufficiently hardened to prevent its dissolving and washing away when the film is treated in warm water in the subsequent operation of relief development hereinafter described. In other respects the film and its sensitive emulsion are of standard type. This insoluble condition of the gelatine containing thesilver image may be effected by suitable treatment during manufacture of the sensitive film, for example, by the addition of a small amount of chrome-alum to the emulsion before coating, or by treatment in a formaline bath after coating. Or instead, and in order to more definitely control the degree of insolubility, the film may be hardened after passing through all the developing, fixing and washing treatment,.for example by passing the printed developed fixed film through a hardening'bath of chrome-alum, formaline, or the like, and then washing and drying the film. Or alternatively,

the hardening agent may instead be combined with the fixing bath, so that fixing and hardening are one operation only. Thorough washing is necessary to remove all soluble salts from the gelatine after any of these treatments. .If however, the colored colloid is of the kind which only requires cold water for its solution, then the aforesaid hardened condition of the silver gelatine layer is not necessary.

Having produced a film with a sound record and-a series of picture records in metallic silver, the next step is to color it.

According to the invention the first step of this coloring process is effected by adhering or cementing to the face of the developed film of metallic:silver images (which are embedded in the layer of hardened gelatine) a multi-colored plaster in the form of a tape or ribbon, which comprises a. layer of non-hardened soluble colored colloid, the said plaster being differently colored in stripes for the sound record and the picture records. The second step consists in so treating the image of metallic silver by a bleaching-hardening bath, of the type hereinafter described, that a chemical re-action is set up which has the eil'ect of rendering insoluble such portions of the colored colloid of the plaster as are in contact with the silver image and of also permit--v removing the silver salts from the film by dis solving them in a bath of sodium-hyposulpliite or other solvent, followed by thorough washing to remove all salts. The result is that the unwanted colored colloid and unwanted silver salts having been dissolved and removed, there is left behind only a colored colloid image in relief which is firmly adherent to the gelatine of the under layer, which latter has been rendered transparent by the bleaching of the metallic silver.

Several variations in the aforesaid four steps can be made (hereinafter described under the heading of modifications), but retainingthe governing principles necessary to produce the finished article or cinematograph positive, which, when complete, comprises a strip of transparent cinematograph film support, an imageless silverless transparent colloid player attached to the support, and insoluble colored colloid relief images of a sound record and a series of insoluble colored colloid relief images of picture records, all being superimposed upon and permanently amalgamated with the face of the said insoluble colorless ayer.

One important feature of the invention consists in the means and method and process of so treating the image of the sound record that it shall differ from the images of the picture records. This is attained by forming the plaster in two different colors of colloid, as parallel stripes, so that when laid upon and cemented to the printed developed film and subjected to the subsequent chemical treatment the plaster will apply different colors to the picture records and the sound record. For example, the picture reccords may be colored, green, blue, red, yellow or the like, whilst the sound record is colored black, grey, or other desired color. Or, alternatively, the picture records may be colored black, green, red, or other color, whilst the sound record is left uncolored or bleached and semitranspare'nt. The method of constructing the plaster to eifect this differentiation is hereinafter described.

The colored plaster with diflerent colored stripes The colored plaster itself is constructed in any of the following forms. The preferred one Form A.--A strip of porous paper is coated upon one surface with a layer of suitable colloid mixed with suitable coloring matter in parallel stripes of different colors as hereinafter described. The plaster-ribbon may be made as a wide web which is afterwards cut into narrow-strips when dry; or the narrow ribbons themselves may be separately coated. Coating is efiected by any suitable known apparatus; for example, wide webs are preferably coated and dried by the apparatus generally used for coating webs of paper or iilm with photographic emulsions, or with the apparatus used for sizing and enamelling paper webs. For ready-cut narrow paper ribbons suitable coating apparatus is that generally used for gumming and drying tapes; or a wet rubber belt running horizontally may be used to which the paper tape is squeegeed; or an adhesive belt may be used to which the paper tape is adhered. by slight pressure; or the tape may be carried by a textile or perforated metal belt which passes over a long suction table, the paper being held to the belt by exhausting air from the suction table by a suction fan. In any of these methods the colored fluid colloid is deposited upon paper web or tape from a hopper, weir, slot or ductor roller having a scraping knife, all of which. are known methods of coating. After the colloid layer has set the coated web or tape is :l by was ing through a drying chamber fed r th filtered and warmed air free from dust the usual man-- her of coating processes.

For the colloid it is possible to use any one of several kinds, or mixtures of two or more, and

among those which are more or su table may be mentioned gelatine, glue, fish-glue, albumen, casein, agar, gum 'arabic, and gum-tragacanth or dextrine. A good colloid is a mixture of glue and gelatine. Another is albumen and fish-glue. Another is gum arabic alone.

The preferred colloid is clear soft gelatine mixed with a snail proportion of very clear glue. This is the colloid used in the description of the process hereinafter illustrated.

The coloring matter incorporated with the colloid must be extremely fine pigment, or a transparent pigment, or a dye-lake of a sufliciently transparent type, or a vat dye in colloidal dispersion, or an aqueous solution of a leuco compound or dyestuif, or any other coloring agent which is sufficiently transparent and is also satisfactorily miscible with the particular form of colloid adopted.- Two or more colors may be mixed to produce any intermediate shade, or any lower or duller tone desired.

The invention can be applied to films of various forms or types, as hereinafter described in detail under the heading of different constructions" and 81 each of these a different arrangemerit of the color stripes of the plaster is necessary.

If the plaster is required for producing only one picture-color and sound it is made of singlewidth only. But if the plaster is required for applying two picture-colors and sound upon one side of a double-width film it is made of double width, with the two colors coated side by side as parallel stripes. Or if the 2-color film is printed upon opposite sides, then two plasters of singlewidth are used, one being provided with sound color. For 3-color work a triple-width plaster may be used having three colors applied in three parallel stripes, one being provided with sound color. Or alternatively a single-width and a double-width plaster may be used, one strip having sound color; or alternatively three singlewidth plasters may be used. For 4-color work a quadruple-width plaster may be used having four colors applied in four parallel strips; or alternativelyfl two double-width plasters; or alternatively four single-width plasters; in each of these 4-color arrangements a sound color is provided on one of the strips.

But whichever of these alternative arrange- .ments is adopted, one of the plasters is provided with a narrow stripe or edge differently treated from the rest of the coloring of the plaster and corresponding in location to the sound record in the margin of the film.

This different marginal stripe for the sound record is formed of colloid containing a different color, for example, black, grey or blue, which, when the entire plaster is laid over the film, covers only the sound track, whilst the other coloring matter covers only the picture records. Whenta film covered by such plaster is treated by the chemical processes hereinafter more fully described, it eventually emerges with its picture records in color and its sound record in black, grey, blue or whatever may be chosen.

In some films two or more sound records are.

required, and in such cases a corresponding number of differently-colored colloid sound stripes are formed on the plaster.

In another arrangement of the plaster a black color for sound can be got by coloring the sound record in one color such as red, and covering it with a green blank space on the opposite side of the film, the green and red forming black when superimposed. a

Although the film-strip is perforated in the usual manner for registration and traction purposes, the plaster tape need not necessarily be perforated, as it can be laid over the film by machine with sufficient accuracy to ensure that the differently colored tracks shall lay correctly over their own portions of the images. If, however, greater accuracy is desired, the plaster tape may be perforated in both margins similarly to the film itself. Or it may be perforated in only one margin, the one next to the sound track. These perforations in the plaster tape will have the effect of very accurately placing and superimposing the sound track of the plaster on to the sound track of the film.

The alternative forms of plaster, and methods of their construction, are as follows:--

Form B.-For this a paper backing is used which has been waterproofed and is therefore non-porous. It may be prepared by impregnating porous paper with hot wax or with an oleate of a fatty acid. Or it may be prepared with a coating of rubber solution. Or with a coating of shellac or other resin. The colored colloid is coated upon this prepared paper in the manner previously described.

The plaster is adhered to the face of the printed film by slightly 'moistening and softening the surfaces of gelatine film and colored colloid, then squeegeeing together between rolls, and afterwards the dry paper backing is pulled off or stripped, leaving the colored colloid firmly attached to the printed gelatine film.

The mode of manufacturing such a plaster is similar to that used in the manufacture of the well-known stripping films which were formerly in common use but are now almost obsolete.

Form C.In this form of plaster no paper backing is used, and it consists entirely of colored colloid alone. This is manufactured in web or tape form by casting or flowing the liquid colored colloid on to a polished moving surface, whereon it is allowed to set and dry, and from which it is finally stripped and then slit or trimmed and reeled for storage and use. The moving surface is preferably an endless belt of polished metal, or a continuous belt of polished celluloid, or a belt of paper or the like which has been coated with celluloid solution or with a resinous varnish to give it the necessary glossy surface. A metal drum or other polished surface may be used for short lengths only.

This colloid plaster is applied to the printed film and otherwise handled and treated in. the same manner as the previously described forms of plaster A and B.

General procedure or routine of operations The method of producing colored films according tothe invention requires the following operations and sequence. They are described as applied to the production of a 2-color film having differently colored images upon opposite sides.

The film to be printed, which is sensitized upon both sides, is first perforated with suitable perforations for registrations and traction purposes.

It is then printed in any known manner, but preferably from a double-width negative by optical projection in a printing machine as shown in the specification of my British Patent No. 373,312, which produces a pair of prints simultaneously, and in accurate registration one with the other, upon opposite sides of a film sensitized upon both sides with gelatino-silver emulsion.

Other methods of printing the film may however be employed.

The double-sided printed film is then developed, fixed, washed and dried in any known type of developing machinery.

The two plasters of different colors are then cemented applied to opposite sides of the film in perfect optical contact therewith in the manner aforesaid and the film, together with its plasters, is passed into the bleaching bath.

The bleached film is next passed into the colloid-dissolving relief-developing apparatus, from which it emerges as a film having pairs of differently colored reliefs or color-component images upon opposite sides, thus producing a complete 2-color film, which is next fixed in a sodium-hyposulphite bath to dissolve the remaining silver-salts, after which the film is washed and dried.

The machine and mocesses.- The plaster may be adhered to the surface of the developed film f in several ways. The preferred way, which is very simple in operation, is carried out in the machine illustrated in the accompanying drawings Fig. l, where a film with two images upon opposite sides is shown in the process of being colored by two plasters applied to opposite sides.

The film (which has been printed, developed, washed and dried, and which carries picture records and sound record formed of metallic silver) is carried on a supply roll F from which it is drawn off by sprocket feed rolls 1 which engage with its perforations, and in its movement is passed through a damping trough and rolls F? by which its gelatine surface is made sufliciently damp, soft and tacky.

It is then led between. two multi-colored tape or ribbon plasters 2 and 3 which are in turn drawn ofi supply rolls L and L The colored colloid of these plasters is dry, but very absorbent, and preferably comprises more or less glue which strongly adheres to the damp film surface and the-two become physically united or amalgamated.

In a modification the gelatine of the film may be impregnated with a dilute solution of glue, glycerine, and water to give it better adhesion as well as softer characteristics.

The three ribbons l, 2 and 3 next pass between ,a set of pressure rolls A and B mounted on weighted frames A and B by which the two gluecolloid faces of the plasters 2 and 3 are squeegeed into perfect optical contact with the faces of the gelatino-silver-images, and complete adhesion of the glue-colloid to the gelatine-sllver image is eflected. The number of rolls used may be more or less than shown according to speed of produc tion desired.

One of the frames together with its rolls is mounted with a floating movement controlled by the weighted arms.

The purpose of this is to ensure that the pressure upon the plasters will always be the same however much they may vary in thickness, and thus prevent variable squeegeeing and too much or too little pressure. It also provides for using two or three bands yet always with the same pressure.

The triple ribbon then passes through a drying chamber K fed with warmed air at a temperature only high enough to dry out some of the moisture but not to melt the colloid.

The triple ribbon then passes into and through a. bath M containing the bleaching solution,

which quickly penetrates the porous paper backings, passes through the colored colloid layers, and attacks the silver in the layers of hardened gelatine of the film, until the silver imagesgare completely bleached and the colored colloid where in contact with such images is rendered insoluble and becomes amalgamated with the hardened gelatine of the bleached silver image layer.

At this stage therefore the two kinds of image areamalgamated or interlocked by the chemical reactions and insolublization of the gelatine and colloid of each kind of image in proportion to the original quantity of metallic silver involved in the reaction. I

The triple ribbon with its bleached images then passes into a colloid-dissolving bath M. In this bath the soluble parts of colored colloid not required to form parts of the colored images are dissolved and washed away, leaving behind on the film a series of colored colloid images which are in relief. As the ribbon emerges from this bath the two paper supports are stripped away by rollers 1W and M The film (now a single ribbon) with its colored relief images, then passes into another bath M containing the fixing solution which dissolves and removes the remaining soluble salts of silver, leaving a layer of original insoluble gelatine free from any trace of the original silver images, upon which are superimposed and amalgamated clear and transparent images of pure colored colloid in relief.

The film is then passed into a washing tank M by which the fixing solution is washed out of the colored colloid images and out of the transparent hardened gelatine layer beneath them. As a final precaution the washed film may be passed through a supplementary final washing tank M though this is not absolutely necessary.

Or it may be treated in the bath and sprays N with a. hardening and flexing solution of alum and glycerine, or with a cellulose varnishing solution either by this final tank M or by the spraying devices N or by both in combination.

The film then passes into and through a drying chamber 1? fed with warm filtered air, and when dry is reeled at P 7 The foregoing description of coloring by two colored images upm opposite sides.

Several other variations are possible in the method of applying the multi-color plaster and bleaching solution to the printed images of metallic silver, and are hereinafter described in detail under the heading of modified details and routine.

If the film requires coloring only upon one side, one plaster only is used, the rest of the procedure being the same.

Bleaching and hardening bath.-..-The type of bleaching and hardening is that commonly known as ozobrome, carbro, or any other similar type. Many modifications in the ingredients and proportions of such baths have been published, and the invention is not limited to the use of any particular one. They usually comprise a mixed solution of a. soluble bichromate and a ferricyanide or a copper salt; and sometimes in addition to these substances soluble bromides are present in the solution. The effect of such a bath is that the metallic silver of the image is transformed into a silver salt, and the gelatine, Where in contact with the metallic silver, is tanned, hardened or insolubilized to an extent in exact proportion to the quantity of metallic silver form-- ing the image. Therefore, according to this process the amount of silver in the film-image definitely controls and regulates the quantity of colored colloid that will be rendered insoluble and will attach. itself to the silver image, and therefore the silver also controls the quantity of such colored colloid that will be left soluble to be dissolved and removed by the dissolving bath. In this way, by careful control of the amount of metallic silver in the primary image in the lower layer of insolubilized gelatine, by suitable adjustments of the length of exposure, time of development, and strength and composition of the dcveloper, it becomes possible to control exactly the amount or depth of color of the secondary image of insoluble colored colloid image in the upper layer. After removal of all the silver, the whole of the gelatine of the lower layer, including the parts where there had been a silver image, becomes transparent, and after removal of the unwanted surplus colored colloid of the upper layer by its solvent bath there is left a relief image of transparent colored colloid only which is superimposed upon and united to an imageless layer of non-colored transparent insoluble or hardened gelatine.

Modifications in details and routine of perations There are quite a number of, possible modifications in practice of the operations that will produce similar finished results, for example:-

The colloid and its solvents.-In the foregoing description it is assumed that a colloid is used which requires heat for its solution before coating and is set by cooling and is dried by warm air after coating. Such a colloid is gelatine, or glue and gelatine. For developing such colloid into relief warm water is therefore used.

But alternatively, a colloid may be used which is soluble in cold, and is solidified and dried by the application of warm air after coating. Such a colloid is gum-arabic, fish-glue, and others of those hereinbefore mentioned. For developing such colloid into relief cold water or other cold solvent is therefore used.

Silver solventa-The ordinary bath of sodiumhypo-sulphite may be used for dissolving the remaining silver salts. Or any other suitable substitute that will easier attack the silver imprisoned in the hardened gelatine, such as the wellknown ferricyanide and hypo bath, or the like. Other modifications of treatment are as follows:-

(1) Hardening of the colloid layer carrying the silver image may be affected during manufacture of the sensitive material. Or it may be ef fected after manufacture but before printing, by passing the sensitive strip through a bath of chrome alum or formaline, then drying. Or where it is desired to bleach after fixing the hardener, such as potash alum may be added to the fixing bath. in any case it is absolutely essential the gelatine of the silver image colloid layer should be rendered sufficiently hard to prevent its solution in the warm water bath, and instead leave it permanently anchored to the cellulose support of the film.

(2-) The printed gelatino-silver layer (if too hard owing to its having been dried after development) may be slightly softened to ensure better adhesion, by passing it through a weak alkaline bath, for example, one containing ammonia or sodium. The colored colloid of the plaster may or may not be treated in the same way, according to requirements. The addition of a little glycerine is useful. The addition of glue hereinbefore referred to may also be made to this softening bath if desired.

(3) The bleaching bath, which serves the dollble purpose of bleaching the metallic silver and of rendering insoluble such portions of the colored colloid as are in contact with such silver, may be applied at either one of different stages.

The preferred method is to adhere the dry plaster to the printed gelatine surface of the film which has first been slightly softened by an alkaline bath, and then apply the bleacher by passing the complete film with its adherent plaster through the bleaching bath, for a sufficient time to allow the solution to penetrate firstly the porous paper support and secondly the colored layer and the silver-image layer, and to thus effect a complete bleaching of the silver therein and effect complete insolubilization of the colored colloid in contact with such silver.

- operation.

(5) Bleaching and hardening of the image may be effected by two separate baths applied in succession at two separate operations, thus allowing more variations of control of the hardening op eration according to the kind of gelatine used.

(6) Bleaching of the image may be effected by incorporating the ingredients of the bleaching bath with the colored colloid before it is coated on to the paper support of the plaster, or by soaking the colored plaster in a bath of bleaching solution and then drying the plaster. When bleaching it is then only necessary to bring one dry strip into pressure-contact with the damp strip to produce a liquid bleacher in situ.

('7) Bleaching can be effected by soaking the printed film until its gelatine is saturated, in a bath of chromic acid, then applying the dry plaster to the film after the surplus solution has been removed from the surface.

both surfaces are under water passing between immersed rolls so placed and constructed that any enclosed air is driven off at the edges. To effect this the position of the two supply spools of plaster needs changing to the position near the spool F.

(11) Other porous materials than paper might be used as the support for the colored colloid in construction of the plaster, provided they are sufficiently porous to allow penetration of liquids through the plaster to the silver. One such material would be a strip of cellulose xanthate, better known as cellophane or viscose, upon the face of which the colored colloid would be coated; or the strip squeegeed into contact with-the wet colored colloid whilst on its preparatory support and dried thereon.

. (12) In another modification the backing of the plaster may be entirely dispensed with, the colored gelatine or other colloid being itself cast in the form of a tape, or cut as a ribbon from a wide web of such material, as herein-described.

(13) The print may be fixed, washed, and dried, after leaving the developing bath. Then stored for coloring at any subsequent period desired. This is the preferred method and in the drawings showing the coloring processes and machinery therefor it is assumed that the already printed developed dried film is stored upon the supply spool F.

(14) The several processes may be combined in one set of machines as one continuous process. In such case after development the plaster is applied, bleaching follows, then fixing, washing and drying. Therefore the wet film passes straight from the developing machine (without intermediate treatment or drying) and enters the coloring machine at the point where it makes contact withand between the two dry surfaces of the two plasters. In such case the damping F" and preliminary drying K are cut out.

(15) Or the processes may be divided into two groups, carried out by two sets of machines, development, washing and drying being one process; and plastering, bleaching, fixing, washing and drying a separate process. The advantage of this latter division is that it enables the coloring and finishing processes to be carried on entirely in a daylight room instead of an extension of the developing room. This is the preferred method illustrated by the drawings.

. (16) Where the stages of treatment are varied, as in modifications 3 to 8, the tanks and sections of the machine illustrated in the drawings are transposed or otherwise modified to suit. such variation of the preferred practice illustrated.

(17) Other modifications may be made in the arrangement of the machine. For example, very soft and adhesive layers may be sufficiently well adhered with only one or two pairs of pressure rolls. But where the film surface is hard a number of pairs of rolls are required to ensure perfect adhesion. The rolls may be arranged horizontally, instead of vertically as shown in the drawings. be placed between the damping apparatus F and the pressure rolls if arranged horizontally immediately after the damping apparatus. The drying chamber K may be placed after the pressure rolls and before the bleaching tank M between the two.

Different constructions of films Another feature of the invention is the adaptability of the process to the production of cine- The plaster tape supply spools L L may matograph positives o! diflerent types or constructions, as illustrated by the following examples:-

\ (A) A monochrome film having positives or one color only on one face of the film, for example black or sepia or blue, thus dispensing with all troublesome toning processes; and provided with a sound record in black, or color, formed alongside the colored picture records.

(B) A two-tone monochrome film, having posltivesln a deep shade of one color, for example sepia, on one side of the film; and on the other side partial positives in a lighter shade or the same color; and a sound record in black or color alongside.

(C) A two-color film having on one side complete positives in black, and on the other side partial positives in blue or red. By this means pictures with moonlight or night effect can be produced by blue and black, and pictures with sunset effects can be produced with red and black and with sound record in black or color alongside. Thus troublesome toning operations to obtain double-tones are abolished.

(D) "Plaster-relief" effects can be produced by printing through a film which is sensitized on both sides, the image depths being so regulated that the light background is printed upon one side only of the film, and the darker objects, such as furniture, figures of actors, trees, buildings, or the like are printed through on to both sides and thus receive a double quantity of color. Or the light parts may be printed upon one side and the dark parts upon the other side and each provided with diflerent shades or intensities of coloring, and a sound record in black or color alongside.

(E) A multi-color film of 2-co1or type such as orange-red and blue-green can be formed with the two colors upon opposite sides of the film, each printed from difierent color-separation negatives which form pair-parts of the same picture, and a sound record in black or color alongside.

(F) A multi color film of 2-color type (as in E) can be formed by printing the two pair-parts side by side upon a double-width film which, after coloring, is slit longitudinally and the parts superimposed and cemented together, and a sound record in black or color alongside one of the colors.

(G) A multi-color film of 3-color type can be produced by making two images, for example red and blue, in the manner already described, and then adding a third color such as yellow by resensitizing and re-printing over one of theother colors, by any of the various well-known methods. Or the third color may be formed first and another color over it. Or the third color can be added by photo-mechanical printing methods or by stencil methods, or in any other known way, and a sound record in black or color alongside one of the colors.

(H) A multi-color film of 4-color type can be more readily constructed according to this invention than by any of the methods previously known and described in some of my own published 4-color processes such as'British specification No. 224,569 and its several divisions and associated specifications. The simplest way of forming such a 4- color film by use of the present invention is by printing two component images (of a set of four) side by side upon ,one face of a sensitive film in one emulsion, and the other two images of the set side by side upon the opposite face of the film in another emulsion. The four images are printed and developed simultaneously by known methods to form groups or our silver images, and are afterwards colored by adhering to one face a plaster comprising two parallel stripes of diil'erently colored colloid, and to the other face another plaster comprising two other parallel stripes of differently colored colloid. By this means all four images are simultaneously colored at one operation as the film is passed through the various baths. A sound record in black or color is formed alongside one of the colors. After printing and coloring the double-width film is slit into two single-widths, which are then superimposed and cemented together with sound images inside as in my British specifications Nos. 232,302 or 246,282. This i-color film is produced substantially as described in my British specification No. 224,573, upon double-width film-material oi the type described in my British specification No. 233,985, but its coloring is effected by the improved method described in the present invention instead of by the methods described in the specification aforesaid, and a sound record black or color is added alongside.

This invention is also applicable for coloring a multi-color him of the type described in my British specifications Nos. 285,227 and 285,228 in which the film is made 0! insoluble gelatine without any cellulose support. The construction methods are the same, but with the coloring etfected according to this invention instead of by I the methods therein described; and the film-material of that film (which consists of gelatine plus a gelatino-silver emulsion and no cellulose support) is itself non-colored before printing, and is only colored (after the silver images have been formed) by the process according to the present invention. A sound record in black or color alongside is also added.

In all these examples the sound record is differently treated or colored from the picture records, by suitable construction of the multi-color plaster as hereinbeiore described.

Figs. 2 to 16 of the accompanying drawings will enable the invention, and its difierences from previously known processes, to be readily understood. In these drawings:--

Fig. 2 is a transverse section through a sensitized film before exposure, I being the transparent celluloid support, 2 the adhesive substratum, and 3, the sensitized silver emulsion layer 0! insoluble gelatine;

Fig. 3 is a similar section after exposure and development showing images of metallic silver in the gelatine layer 3, the images 3* being the sound record of metallic silver and 3 the picture records of metallic silver.

Fig. 4 is similar section showing the colored plaster 4 with its paper backing 5 adhered to the face of the insoluble gelatine layer 3 with the developed images 3 and 3 of metallic silver embedded therein.

Fig. 5 is a. similar section of the finished positive'showing the transparent color picture records 3 in relief and black sound record 3 in relief to the metallic silver images embedded in the hardened gelatine layer 3 after the film has passed through the developing bath and before passing to the bleaching bath, the plaster I having a wide orange red stripe 4 for coloring the picture rec.

. (green).

ords and a narrow black stripe i for the sound record.

Fig. 7 is a perspective view showing the paper backing 5 of the plaster 4 being stripped from the film after the latter has passed through the' of transparent insoluble colloidin place of the black-silver, with the colored colloid images superimposed upon and firmly amalgamated with the insoluble colloid parts of the lower layer of insoluble transparent gelatine. These colored colloid images are in relief, and stand above the lower layer of gelatine, to which they are permanently united or amalgamated as shown in Fig. 5.

Figs. 9 and 9% show how a 2-color film is made with orange-red picture component images upon one face and blue-green picture-component images upon the opposite face, and black sound record not shown alongside either the red or green picture records. Fig. 9 being a longitudinal section of the film with developed metallic silver images 3 on each side and colored plasters 4 adhered thereto and Fig. 9 being the finished 2-color film with orange-red and blue-green relief images upon each opposite sides forming complete Z-color picture records the black sound recordbeing formed parallel therewith in the margin of the film. The finished film comprises a transparent central support I of celluloid, two layers 2 of adhesive substratum 2, two layers 3 of insoluble transparent imageless silverless gelatine. an insoluble colloid relief and picture ii on one face and an insoluble colloid relief green pictures 3 on the other face.

Figs. .19, 11, 12 and 13 illustrate the steps in forming the 2-color film Fig. 13; this is produced from the double-=width printed film Fig. 10 which shows the developed black metallic silver images;

the paper backed colored plaster Fig. ll adhered.

to the silver images; Fig. 12 shows the film with its colored colloid relief images, and Fig. 13 the finished film with the two parts slit andthen ce-' mented together face to face; (or they may be cemented back to back, or face to back) Fig. 14 shows a multi-c'olor plaster d for a 2-.color and sound film having three colored stripes; 4, being forthe black sound record and 4 4 for the two color-picture records respectively.

.Fig. 15 shows a multi-color plaster d for a 3-color and sound film having four colored stripes; 4 (black) 4' (magenta) 3 ,(yellow) and 4 (blue) for the black sound record and the three colored picture records respectively.

Fig. 16 shows a pair of multi-color plastersfor producing a four-color and sound film built up of two double width films; the first plaster has 3 colored stripes 4" (black) for the black sound rec- 0rd, 4 (red) and 4 (yellow) and the second plaster two colored stripes 4 (blue) and I he slit into two strips. In embling the red stripe goes over the green stripe and the yellow over the blue.

Instead of the tape or plaster being of the same width as the film a narrow tape or plaster may be employed provided with a layer of colored They may be prin ed as one strip or l colloid the width of the picture records only.

so that when applied to the face of the printed film the picture records are colored but the sound record is not colored since the plaster leaves it entirely exposed. The sound record is thus differentially treated from the picture records and may be finished either as black silver or as colorless bleached silv er.

In producing such film an ordinary positive film sensitized with gelatino-siiver-emulsion is exposed or printed under a negative having color records and under a negative having a sound record, which latter is printed parallel to the former. Bothmay be printed simultaneously.

It is next developed to produce images of both kinds of record in metallic silver. It is then washed, after which the plaster tape or ribbon is applied to the silver picture images whilst the film is still wet.

Or if preferred the developed film may be fixed,

hardening bath of well-known type by the chernical action of which the silver is bleached and the colored colloid is rendered insoluble wherever in contact with silver and in exact proportion to the amount of silver present in the image.

The bleached image is then treated in a solvent by which the surplus colored colloid not used to form the image is dissolved and removed. It is also treated in a solvent by which the silver salts are dissolved and removed, leaving behind a film which comprises a transparent support, a transparent imageless. layer of insoluble gelatine attached to the support, and a relief image of colored colloid superimposed upon and standing above the transparent gelatine layer, representing one ofthe. color parts of the picture-record.

If it is desired to form the sound record in black metallic silver it is coated with a narrow stripe of protective varnish after development fixing washing and drying, in order that the black silver may be protected fromthe bleaching bath in the subsequent operation and therefore remain black permanently. Or such protective layer may be a strip of adhesive waterproof tape (such as rubber covered plaster). Either the protective varnish or protective tape may be applied. to the film before development or after development and drying.

But if it is desired to form the sound record with a colorless image, such protective layeris omitted and the sound record is bleached at the same time as the picture record and the silver is dissolved and removed in the fixing bath as aforesaid.

After all operations aforesaid have beencompleted the film is washed and dried. i

What I claim as my invention-and desire to protect by Letters Patent is:--

1. An improved process for producing a comently colored colloid mounted on a porous paper support applied to the film simultaneously, the stripe covering the picture areas being of one color and the stripe covering the sound record being of a different color; (1)) passing the film and the colloid tape adhered thereto into a bleaching and hardening bath by the reaction of which the silver images are bleached and the colloid stripes are rendered insoluble whenever in contact with the silver of the images and in direct ratio to the quantity of silver in the images; (0) dissolving and removing all unwanted colloid and removing the porous paper support that has not become insolublized and amalgamated with the underlying silver image, thus producing relief images of insoluble colloid; (d) dissolving and removing by a fixing bath the unwanted silver salts thus producing a clear transparent imageless layer of gelatine upon which the aforesaid colloid relief images are superimposed; and

finally Washing and drying the film; thus producing a positive cinematograph film strip having a layer of imageless transparent gelatine firmly attached to its transparent cellulose support, and another layer comprising sound and picture records of colloid reliefs in parallel formation superimposed upon and firmly attached to the aforesaid imageless layer of hardened gelatine, the picture records being in colored colloid reliefs and the sound record being in a differently colored colloid relief, these colloid relief images, being the only images left on the film.

2. An improved process for producing a combined color picture and sound record cinematograph film having the picture records formed in relief in colloid of two colors and the sound record in relief in colloid of a third color, the two records in relief colloid being formed simultaneously from a film in which both records have first been formed by exposure and development as primary images of metallic silver embedded in a layer of hardened. gelatine, the said process comprising the following steps in combination:- (a) applying in optical contact on to the aforesaid silver images a tape carrying three parallel stripes of differently colored colloid mounted on a porous paper support applied to the film simultaneously, the stripes covering the picture areas being of two different colors and the stripe covering the sound record being of a third color;

7 (b) passing the film and the colloid tape adhered ver image, thus producing relief images of insoluble colloid and removing the porous paper support; ((1) dissolving and removing by a fixing bath the unwanted silver salts thus producing a clear transparent imageless layer of gelatine upon which the aforesaid colloid relief images are superimposed; and finally washing and drying the film; thus producing a positive cinematograph film strip having a layer of imageless transparent gelatine firmly attached to its transparent cellulose support, and another layer comprising sound and picture records of colloid reliefs in parallel formation superimposed upon and firmly attached to the aforesaid imagele'ss layer of hardened gelatine, the picture records being in colored colloid reliefs and the sound record being in a differently colored colloid relief, these colloid relief images being the only images left on the film.

3. An improved process for producing a combined color picture and sound record cinematograph film having the picture records formed in relief in colloid of a plurality of colors and the sound record in relief in colloid of a difierent color from any of the colors forming the picture records, the two records in relief colloid being formed simultaneously from a film in which both records have first been formed by exposure and development as primary images of metallic silver embedded in a layer of hardened gelatine, the

said process comprising the following steps in combinatiom-(a) applying in optical contact on to the aforesaid silver images a tape carrying a plurality of parallel stripes of differently color'ed colloid, mounted on a porous paper support applied to the film simultaneously, the stripes covering the picture areas being of a plurality of different colors and the stripe covering the sound record being of a different color from any of the colors of the stripes covering the picture areas;' (b) passing the film and the colloid tape adhered thereto into a bleaching and hardening bath by the action of which the silver images are bleached and the'colloid stripes are rendered insoluble whenever in contact with the silver of the images and in direct ratio to the quantity of silver in the images; (0) dissolving and removing all unwanted colloid that has not become insolublized and amalgamated with the underlying silver image, thus producing relief images of insoluble colloid and removing the porous paper support; (d) dissolving and removing by a fixing bath the unwanted silver salts thus producing a clear transparent imageless layer of gelatine upon which the aforesaid colloid relief images are superimposed; and finally washing and drying the film; thus producing a positive cinematograph film strip having a layer of imageless transparent gelatine firmly attached to its transparent cellulose support, and another layer comprising sound and picture records of colloid reliefs in parallel formation superimposed upon and firmly attached to the aforesaid irnageless layer of hardened gelatine, the picture records being in colored colloid reliefs and the sound record being in a differently colored colloid relief, these colloid relief images being the only images left on the film.

JOHN THORNTON.

Images