US1992169A - Coloring photographic images - Google Patents

Coloring photographic images Download PDF

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Publication number
US1992169A
US1992169A US669559A US66955933A US1992169A US 1992169 A US1992169 A US 1992169A US 669559 A US669559 A US 669559A US 66955933 A US66955933 A US 66955933A US 1992169 A US1992169 A US 1992169A
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United States
Prior art keywords
iodid
iodin
gelatin
solution
image
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US669559A
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English (en)
Inventor
Percy D Brewster
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Individual
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Individual
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Priority to US669559A priority Critical patent/US1992169A/en
Priority to GB27964/34A priority patent/GB449679A/en
Priority to FR790109D priority patent/FR790109A/fr
Application granted granted Critical
Priority to DEB168821D priority patent/DE648567C/de
Publication of US1992169A publication Critical patent/US1992169A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
    • G03C5/40—Chemically transforming developed images
    • G03C5/48—Mordanting

Definitions

  • This invention (subject of the present application, a continuation in part of my copending application Serial No. 143,298, filed October 21, 1926, renewed July 30, 1932) relates to. color cinematography, more particularly to changing or transforming a silver image into one composed, at least in part, of dye, and the chief object of the invention, stated generally, is the conversion of the silver image into a silver iodid or like dyeadsorptive compound of adequate dye-mordanting power, and composed of clearly defined grains or deposits which occupy substantially the same positions as the corresponding silver grains or deposits of the original image.
  • adsorption refers chiefly to the property of taking up and holding the dye-stuff, and does not necessarily'imply a chemical reaction.
  • the image After dyeing, the image is sharply defined, following well the general contour of the'original silver grains, but the dye-adsorption is so poor and the opacity of the image so great that for purposes of color photography, and particularly for projection upon a screen as in cinematography, it is necessary to remove all or a large portion of the silver iodid, as by treatment in a hypo (sodium thiosuliate) bath.
  • This removal of the silver iodid is not satisfactory, as it requires a long time and causes or results in severe bleedingfof the dye image into the undyed gelatin, which can not be stopped by any known means.
  • the clearing operation destroys what was the best feature of the Traube patent, namely the sharpness of the image. For such reasons this method has never proved usable in practical work, although much time and labor have been expended upon it.
  • the Miller process gives an image of high transparency and brilliancy of coloring, but lacking in sharpness, and from long experience with the process I have come to the conclusion that the lack of sharpness is due to the solubility of the mordanting compound in the bleaching solution, which causes or permits migration of the molecules or clumps of the compound from their original positions into other parts of the gelatin, especially into the highlights, where such migration is most objectionable as causing a lack of definition and-a clouding of the whites when the image is projected.
  • the effect is as if there were an almost total destruction of the grain contour in the highlights, and a substantial bleed from the heavy grains of the shadows.
  • colloids or gels vary widely in ability to adsorb dye and retain definition, and I believe that the greater the number of potassium iodid mols in the complex in proportion to the number of silver iodid mols, the greater the tendency, in general, to form a mordant of brilliant color when dyed but of poor image definition, as is characteristic of the Miller process; and conversely, the-smaller the number of silver iodid mols in proportion to those of potassium iodid the greater the tendency to form a mordant of the Traube type, of good image definition but opaque and dull in color.
  • the effect is to allow a certain amount of migration of the gel complexes of the image, especially in the highlights, thereby impairing definition and causing poor washing of the whites or clear portions of the image. Itseems likely that silver molecules on the surface of the heavy or shadow portions of the image are first converted and then, while the underlying silver. grains are being converted, are more or less dissolved, causing the bleed from heavy image densities characteristic of the .Miller process.
  • the film is first treated with a preliminary or preparing solution and then with an acid reagent or reagents in solution, which causes iodin to be'liberated within the gelatin (impregnated with the preliminary solution) merely by the penetration of acid ions.
  • mordant so produced is highly adsorbent of dye and produces brilliant images with the sharpness of definition necessary for color-cinematography.
  • the best quantitative analysis, at present available to me, of mordants havingthese' desirable characteristics indicates, and it is my present belief, that the ratio of silver iodid to potassium iodid therein ranges from about 1/20 to about 1/40, but I'do not desire to be bound by these limits, which on the basis ofthe analysis represent the optimum for the mordant.
  • An excellent general method of reto be carried by its solvent into leasing this iodin is to impregnate the gelatin with an iodid and a suitable oxidizing agent in neutral or alkaline solution (sometimes referred to hereinafter as the presoak"), and then treat the film with acid ions in liquid or gaseous form.
  • oxidizing agents produce this reaction and grees for the production of dye mordants.
  • inorganic oxidizing agents are the iodates, periodates, bromates, perbromates, chlorates, perchlorates, chromates, dichromates, ferri-cyanides, permanganates, nitrites, peroxides, and certain metallic salts having double valence such as the stannates, stannic salts, manganic salts, ferric salts, cupric salts, plumbic salts and so forth.
  • Iodin can be liberated in the gelatin by treating the-same (impregnated or pre soaked" with mately one minute. If the gas is too strong and 76 protecting the highlights.
  • the mechanism of my improved process in which the image is bleached by a reaction which liberates iodin within or largely within the emulsion is that when or as the highlights and thin parts of the image are bleached the grains or grain clumps of the conversion-product are protected from being dissolved in the iodid or other iodin salt solution by an increasing iodin content in the immediate vicinity of the grains.
  • the conversion of silver in the shadows to silver iodid consumes theiodin almost if not quite as fast as the iodin is provided, so that the grains in the shadows are not acted upon by a high iodin content such as is shadows bleach properly to the gel condition, and as soon as they are completely bleached they also are protected by the increase of iodin content.
  • the novel action described above is obtained by impregnating the emulsion, before bleaching with a solution containing iodin salts, preferably including an iodate, from which iodin can be liberated at relatively slow re'action velocity while the image is being bleached by treatment with an acid reagent, so that the amount of iodin in the emulsion around or in the immediate vicinity, of the grains which are bleached or which are undergoing bleaching, will progressively increase.
  • iodin salts preferably including an iodate
  • the image for example on a cinematographic positive film, is developed, fixed in a plain fixing bath, washed, hardened in a 'weak solution of formaldehyde, and dried without washing. After drying the film is treated with a strong solution of potassium chlorate or other non-staining oxidizing agent. After thorough washing it is treated, preferably without drying, in a solution containing an iodid and an iodate, say of the following composition:
  • ammonia or other suitable alkali serves to prevent premature liberation of iodin, as I prefer to have the solution quite clear and free from iodin, though it may contain enough free iodin to give a straw color without apparent harm.
  • the film is well soaked in the above presoak solution, for a time which may vary from a few seconds to 2 or 3 minutes, depending upon circumstances, such as the thickness of the emulsion, the degree of pie-hardening to which it had been subjected, the amount of water already contained in it, etc.
  • the emulsion of the film is well charged 5 with the presoak, it is bleached by treatment with an acid solution, or with an acid gas.
  • the solution may be, for example, either of thefollowing:
  • the purpose of the aluminum acetate or-ammonium chrome alum or like metallic salt in the bleach is to aid in coagulating the silver iodid.
  • Such salt may be included in the presoak instead of in the bleaching solution, in which case I prefer the presoak to be as follows:
  • the iodid-iodate preparing solution or pre- 7 soak is inherently stable but should be either neutral or slightly alkaline, and I accordingly include the alkali, preferably ammonium hydroxide,
  • the bleach may otherwise be varied, it should be sufficiently acid to cause or permit liberation of iodin from the iodate or iodid, or both, with which the emulsion was charged by its immersion in the presoak solution. It is my present belief that the reaction between the iodid and iodate of Solution A, and the acid ingredient of bleaching Solution B2, follows the equation an analogous reaction taking place when an acid other than acetic is used. 0
  • the proportion of potassium iodate in the presoak or perparing solution depends, in general,
  • the amount of potassium iodid in the gelatin should be suflicient to so condition the latter that it will not produce a mordant of the opaque Traube form and to produce more of the visible yellowish-white sil- "ver' iodid, while increase of the iodid component to sufficient concentration produces the invisible type of gel; but in my process the iodin appears to have an eifect analogous to a toughening, as it were, of the gel structure.
  • iodid-iodate Acidulating an iodid-iodate mixture in which the proportion of these salts is five mols of iodid and one mol of iodate, releases all the combined iodin, but I do not limit myself to these proportions.
  • An excess of iodid may sometimes be employed, as with hard gelatin, or an excess of iodate may be incorporated.
  • the amount of iodid-plusiodate may vary widely but is preferably between 50 and 100 grams per liter, the higher concentration tending to a more colloidal condition of the mordant, but I prefer a concentration which will, with a given bleaching reagent, produce a clear faintly whitish mordant, characterized by substantial transparency in the highlights and translucency elsewhere.
  • the presoak that is, the iodid-iodate solution, may also be prepared by treating iodin with a solution of an alkali, as for example sodium or potassium hydroxid.
  • a soluble iodid preferably an alkali iodid, as for example sodium, potassium or ammonium iodid, but soluble iodids or" the base metals may be used, say stannic iodid. Base metal iodids, however, are prone to interfere with the smodth action of the bleach.
  • a metallic salt to aid in coagulating the colloidal silver iodid to a gel as for example aluminum acetate or ammonium chrome alum.
  • the acid employed-in (a) will alone cause conversion of the silver image to a colloidal iodid containing silver, but conditioning of the gel is aided by the metallic salt.
  • the bleachsolution will produce an excellent mordant in the total absence of a metallic coagulant, but greater sharpness is obtained if the gel is first formed and the tin excess iodin is allowed to toughen or harden it, as described above.
  • the free acid would ordinarily retard or impede the effect of the alum, but the conditions are such that the acid is consumed approximately as fast as it penetrates the gela- (d) Iodin to retard the diffusion, into the bleaching solution, of iodin produced within the Although iodin in the bleaching solution has but little effect on the silver image, it is impoi'ta'nt to prevent, as far as possible, the iodin which the gelatin has brought with it, from the presoak or preparing solution, from going into the bleaching solution.
  • the iodin salts carried by the gelatin supply suflicient iodin for the conversion of the silver image, but if there is any difference in the salt pressure in the bleaching solution and in the emulsion, there is a tendency to diffusion of the iodin and iodate from the emulsion into the solution, which would weaken the action of the iodin and by the circulation in the emulsion tend to dissolve the gel of silver iodid and cause it to permeate the emulsion, this permeation being apparent as bleeding and lack of sharpness when the image is dyed. 1
  • the excess liquid of the presoak or preparing solution is re-' moved from the surface of the film, as by an airblast or other means which will not harm the image, after which the treatment with a gas or the like may be conveniently effected by passing the film into or through an atmosphere carrying the acid gas or acid ions.
  • an atmosphere may consist, in the case of a weak acid, of the acid vapor or gas itself, as for example the vapor of acetic acid at ordinary temperatures,
  • the acid atmosphere should have about the same acidity as theyapor of glacial acetic acid at a temperature of approximately 20 C. with such acidity the film is usually bleached in about one minute.
  • concentration of the acid vapor or acid ions the action is faster, but if too fast the image may lack the desired transluoency. In any case a concentration suitable for good results may readily be found by trial.
  • the presoak or preparing solution employed when the acid gas method is to be used to bleach the image may be the same as when a solution is used for the latter purpose but I prefer the following composition:
  • Process of converting into a dye mordant a developed and fixed photographic silver image carried by a gelatin coating and subsequently coloring the image comprising washing the gelatin coating and treating the same with formaldehyde, drying the coating, impregnating the coating with an iodid-iodate mixture, causing liberation of iodin therefrom to convert the silver of the image into an iodin compound, and subsequently dyeing the image.
  • a photographic image composed of a dyed mordant embedded in gelatin and consisting of silver iodid gel substantially insoluble in potassium iodid solution.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
  • Coloring (AREA)
US669559A 1926-10-21 1933-05-05 Coloring photographic images Expired - Lifetime US1992169A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US669559A US1992169A (en) 1926-10-21 1933-05-05 Coloring photographic images
GB27964/34A GB449679A (en) 1926-10-21 1934-09-29 Improvements in dye mordanting processes for colouring photographic silver images
FR790109D FR790109A (fr) 1926-10-21 1935-02-25 Perfectionnements à la photographie en couleurs
DEB168821D DE648567C (de) 1926-10-21 1935-02-26 Verfahren zum Umwandeln des in einer Gelatineschicht befindlichen Silbers photographischer Bilder in eine farbziehende Beize

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14329826A 1926-10-21 1926-10-21
US669559A US1992169A (en) 1926-10-21 1933-05-05 Coloring photographic images

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FR (1) FR790109A (fr)
GB (1) GB449679A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2423504A (en) * 1943-09-22 1947-07-08 Polaroid Corp Process for forming lightpolarizing images
US2467359A (en) * 1946-01-23 1949-04-12 Rubinstein Leon Photographic oxidizers and resists
US2668762A (en) * 1946-02-20 1954-02-09 Rubinstein Leon Process of producing screens

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2423504A (en) * 1943-09-22 1947-07-08 Polaroid Corp Process for forming lightpolarizing images
US2467359A (en) * 1946-01-23 1949-04-12 Rubinstein Leon Photographic oxidizers and resists
US2668762A (en) * 1946-02-20 1954-02-09 Rubinstein Leon Process of producing screens

Also Published As

Publication number Publication date
GB449679A (en) 1936-06-29
FR790109A (fr) 1935-11-14

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