US3189452A

US3189452A - Color-forming photographic process utilizing a bleach-fix followed by a bleach

Info

Publication number: US3189452A
Application number: US157096A
Authority: US
Inventors: Charleton C Bard; George P Varlan
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1961-12-05
Filing date: 1961-12-05
Publication date: 1965-06-15
Anticipated expiration: 1982-06-15
Also published as: GB1026496A; BE625533A; DE1202638B

Description

June 15, 1965 COLOR-FORMING PHOTOGRAPHIC PROCESS UTILIZING A DENSITY DENSITY c. c. BARD ETAL $189,452

BLEACH-FIX FOLLOWED BY A BLEACH Filed Dec. 5, 1961 12,-\ YELLOW DYE DENSITY DYE DENSITY l l l l I I l l l l 1 4! DYE DENSITY MAGENTA DYE DENSFE'Y 1 I I i l l l 1 l l I l I I i I Chaz'leton G Bard George RVarZan INVEN TORS 311%Z4-[M WW m Arrows United States Patent Ofi ice Patented June 15, 196-5 CSLOREGRMENG PHQTGGEEAPHEC PROCESS A BLEACH Charleton C. Bard and George P. Varlan, Rochester, N.l., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Eersey Filed Dec. 5, 1961, fier. No. 157,096 4 (Ilaims. (Cl. 96-55) The present invention relates to photography and particularly to the processing of color photographic materials. Still more particularly, the invention relates to a shortened method for the processing of coupler-incorporating, colorforming photographic films and prints.

In the usual method for processing of exposed multilayer coupler-incorporating, color-forming photographic materials, the color developer bath is usually followed by consecutive baths comprising a fix, a bleach, and a fix again with an intervening wash step between each of the baths indicated. As is well known, the fix bath is employed to remove the undeveloped silver halide from the developed emulsion layers while the bleach bath is employed to oxidize the metallic silver formed by development to silver halide. The second fix is normally employed to remove the silver halide formed by the previous bleaching step so that the emulsion layers are cleared of residual silver and silver halide. This leaves essentially a colored image of cyan, magenta, and yellow dye densities as formed at the time of development by coupling of the incorporated couplers with oxidation products of a primary aromatic amino developing agent contained in the color developer bath.

It has been of interest for some time to shorten the time required for processing of color-forming photographic materials. 'Ihe present invention has quite unexpectedly found a shortened method for the processing of certain color-forming photographic materials without sacrifice in image quality and which is adapted for use in the processing of photographic materials of a high silver content. By high silver content in the present specification, we mean materials having a silver content of 200 mg. per square foot or higher. The image quality obtained according to the present invention is illustrated in the accompanying drawing in which:

FIG. 1 shows the colored image densities obtained in a standard photographic process FIG. 2 shows the colored image densities obtained using the present shortened process.

Accordingly, it is an object of the present invention to provide a novel shortened process for the processing of color-forming photographic materials. A second object is to provide processing baths for use in said shortened process. Other objects will become apparent from a reading of the specification and appended claims.

These objects are accomplished by treating an exposed color-forming photographic material of the invention, after color development and washing, with a combined bleaching and fixing solution followed by a separate bleaching solution. According to the invention, an intervening wash between the treating baths of the invention is not required. After the bleaching bath of the present process, the photographic material can be washed and then treated with a conventional bufier bath, if desired, as normally employed in the art.

Photographic materials of the type processed according to the present invention comprise materials having color-forming couplers contained in respective layers of a multilayer photographic element. Materials of this type have been described in a number of US. and foreign patents, for example, in US. Patents 2,322,027, Tune 15, 1943; 2,407,210, September 3, 1946; 2,474,293, June 28, 1949; 2,640,776, June 2, 1953; and 2,956,876, October 18, 1960. Color films of the invention include the so-called negative-positive type materials as well as reversal materials. The photographic multilayer color materials of the invention comprise elements having usually three selectively sensitive emulsion layers coated on one side of a photographic support. Sensitive layers of the elements of the present invention contain color-forming couplers to form the complementary dye to wmch a particular layer is sensitive. In sensitive materials of this type, the uppermost layer is generally blue-sensitive and normally in corporates a yellow-forming coupler. The next layer generally comprises a filter layer which is yellow in color and blue absorbing and being placed under the top layer absorbs most of the blue light thus preventing unwanted blue exposure below the filter layer. The next layer is generally green-sensitive and usually incorporates a magenta-dye forming coupler. The emulsion layer adjacent to the support is generally red-sensitive and according to the present invention normally contains a cyan-dye forming coupler. Sometimes multilayer photographic elements as used in the present invention contain additional silver halide emulsion layers or other interlayers for specialized purposes. In photographic print materials, frequently the yellow filter layer is omitted and the arrangement of silver halide emulsion layers may be changed for the purpose of obtaining more accurate recording of the color negative.

In accordance with the present invention, the combined bleaching and fixing solution can be prepared by combining a number of silver bleaching agents and silver halide fixing agents. For example, where freshly prepared combined solutions can be employed, a suitable bleaching agent can comprise an alkali metal dichromate (e.g., sodium dichromate, and potassium dichromate), an alkali metal ferricyanide (e.g., potassium ferricyanide, and sodium terricyanide), ferricyanide-bromide, permanganate (e.g., potassium permanganate), quinone, and the like. Such bleaching agents can be combined in freshly prepared solutions with such fixing agents as alkali metal thiocyanates (e.g., sodium thiocyanate and potassium thiocyanate), ammonium thiocyanate, alkali metal thiosulfate (e.g., sodium thiosulfate and potassium thiosulfate), ammonium thiosulfate, thioureas, and alkali metal selenocyanates (e.g., sodium selenocy anate and potassium selenocyanate). Combined baths of this type, however, are stable over a very short period of time; and, consequently, optimum results can be obtained using fresh solutions only. Some improvement in stability in such baths can be obtained by the addition to the bath of a thicken-ing agent which results in the formation of a viscous solution. Such viscous solutions can be applied as a surface layer on the photographic material to be processed. Suitable thickening agents for this purpose include a wide variety of materials, such as carboxymethylcellulose, ethylcelluiose, gelatin, poly-vinyl alcohol, collod-ion, polyvinyl acetals, cellulose esters, and the like.

More stable combined bleaching and fixing solutions comprise, for example, a ferric chloride solution containing a sequestering agent such as ethylene diamine tetra-v acetic acid tetnasoclium salt, and a fixing agent such as sodium thiosulfate. Other combined solutions of the j .The separate bleaching solution for use in the present invention can be prepared by dissolving an appropriate amount of a silver bleaching agent of the type mentioned baths have been described, for example, in US. Patents 2,745: ,000, May 29, 1 956; 2,113,329, April 5, 1938; and 2,252,718, August 19, 1941.

Photographic silver halide emulsions useful in the process of the present invention can be prepared according to known methods such as those described in Hewit- -s on and McClintock, US. Patent 2,618,556, November '18, 1952. Emulsions prepared by other methods can also 1 ganic and have boiling points above about 175 C. These cellulose nitrate, etc., water-insoluble, but Water-permeable cellulose ethers, Water-insoluble but water-penneable natural and'synthetic resins, high-boiling, substantially Water-insoluble crystalloidal materials, such as N-n-aniylphthalimide, tetrahydrofurfuryl benzoate, triphenyl phosphate, n-butyl phthalate, and the like (see also U.S.

2,801,717). r Our invention isespecially. useful with emulsions in which the color-former is dispersed in one or more of the aforesaid substantially water-insoluble, high-boiling, crys talloidal materials. These crystalloidal materials are orcrystalloidal materials have a high solvent action for the i be used to equal advantage in the invention. These emulsions can be sensitized, for example, with chemical sensitizers as described in US. Patents 2,540,085; 2,597,856; and 2,597,915; with azaindene compounds as disclosed in US. Patent 2,716,062; with condensation products of alkylene oxides as described in US. Patent 2,400,532,- and with the additives as mentioned in US. Patent 2,937,- 3089. In short, the photographic emulsions of the invention can contain addenda or not, as Well known in the art, to improve the character of such emulsions.

: Photographic elements of the present invention can be prepared by employing any of the emulsions previously described. Emulsions of the present type can be coated as separate layers on typical supports as used in preparzing such photographic elements, such as cellulose acetate film, resin film, paper etc. elements of the invention which contain separate layers and are therefore referred to as multilayer materials have been described in such US. Patents as 1,055,155, 2 March 4, 1913; 2,304,940, December 15, 1942; and 2,322,- 027, June 15, 1943. The present invention is also applicable to color photo- 'g-naphic emulsion materials wherein the emulsions are 1 mixed instead of disposed in separate layers. Moreover, particular emulsions can be employed in the invention which comprise single emulsions containing color tormers for making component color pictures. The emulsions of the present invention, in addition to containing color- 1 formers (couplers) as previously indicated, can also con- ;tain sensitizing dyes in addition to the usual addenda' j employed in emulsions of the present type.

permeable materials set forth in U.S.'Patents 2,304,940

and 2,322,027, such as Water-insoluble but water color-formers and for the dyes formed therefrom andare permeable to photographic processing solutions. These crystalloidal materials have been referred to as oil formers because they have the property of producing an oily or liquid solution when mixed with the coupler, even though the cou ler is a solid. The crystalloidalmaterials. are generally liquid'at ordinary temperatures or low melting solids (below 100 C.), The most useful compounds contain one or more polar groups such as'halogen, hydroxyl, carboxylic acid, amide, ketone, etc.

The following couplers are suitable for use in our inven-- tion. It is to be understood that this list is not exhaustive, but merely to typify compounds which maybe used."

Courrans PRODUCING CYAN IMAGES 5- (p-amylphenoxybenzenesulfonamino) -l -naphtho1 5- ('N-benzyl-N-naphthalenesulfonamino) -1-naphthol 5-(n-benzyLN-n-valerylamino)-1-naphthol S-caproylarnino-l-naphthol V 2-chloro-5 (N -n-valeryl-N-p -is opropylbenzylamino) ,-1-

naphthol 2,4-dichloro-5- (p-nitrobenzoyl-fl-o-hydroxyethylamino)1 naphthol 2,4-dichloro-S-palmithylamino-l-naphthol 2,2'-dihydroXy-5 ,5 -dibromostilbene 5-diphenylethersulfonamido-l-naphthol Typical photographic Any of the acylaminophenolcouplers disclosed in United States Patents 2,423,730, dated July 8, 1947, can also a be used as couplers for the cyan image.

The emulsions of the present photographic elements a permeable cellulose esters, e.g., Water-insoluble, but waterpermeable cellulose acetate, cellulose acetate-phthalate,

Courrens PRoDUcrNo MAGENTA IMAGES l-p-sec. amylphenyl-3-n-amyl-5-pyrazolone 2-cyanoacetyl-5- (p-sec. ,amylbenzoylamino)rcournarone 2-cyanoacetylcoumarone-i(N-n-amyl-p-tert. amylsulfanilide.) 2-cyanoacetylcoumarone-5-sulfon-N-n butylanilide 2-cyanoacetyl-5-benzoylaminocoumarone 7 Z-cyanoacetylcoumarone 5rsulfondimethylamide Z-cyanoacetylcournarone 5-sulfon-N-methylanilide Z-cyanoacetylcoumaron e-5- (N- y-phenylpropyl) -ptert, amylsulfonanilide V 1-p-laurylpheny1-3 -methyl- 5-pyrazolone l-{i naphthyl-3-arnyl-5 pyrazolone l-p-nitrophenyl-Z-n-amyl-5-pyrazolone' 7 lfi-phenylene bis-3%l-phehyl-S-pyrazolone) r I V 1-phen'yl-3 acetylamino-5-pyrazolone COUPLERS PRODUCING YELLOW IMAGES N-amyl-p-b enzoylacetaminob enzenesulfonate N- (4-anisoylacetaminobenzenesulfonyl) -N-b enzyl-mtoluidine N- (4-b enzoylacetaminobenzenesulfonyl) -N-b enzyl-mtoluidine N- (4-benzoylacetaminob enzenesulfonyl) -N-n-amyl-ptoluidine N- (4-benzoylacetaminob enzene sulfonyl) -N-benzylaniline wp-B enzoylb enzoyl) acetanilide w-B enzoylacet-Z,S-dichloroanilide w-Benzoyl-p-sec. amylacetam'lide N ,N-di o-benzoylacetyl) -p-phenylenediamine N,N-di- (acetoacetamino) diphenyl 4,4-di acetoacetamino) -3 ,3 '-dimethyldipheny1 p,p'-Di-(acetoacetamino) diphenylmethane Ethyl-p benzoylacetaminobenzenesulfon ate N onyl-p-b enzoylacetaminob enzenesulfonate N-phenyl-N- (p-acetoa cetaminophenyl) -urea In the development of exposed photographic silver halide emulsion layers using the couplers of our invention, any color-forming developer containing a primary amino group may be used. These include developers having two primary amino groups as Well as those having one of the amino groups substituted or having substituents in the ring, such as the alkyl phenylene diarnines. These compounds are usually used in the salt form, such as the hydrochloride or the sulfate which are more stable than the amines themselves. The suitable compounds are diethyl-p-phenylenediamine hydrochloride, monomethyl-pphenylenediamine hydrochloride, dimethyl-p-phenylenediamine hydrochloride, and Z-amino-S-diethylaminotoluene hydrochloride. The p-amino phenols and their substitution products may also be used where the amino group is unsubstituted. All of these developers have an unsubstituted amino group which enables the oxidation products of the developer to couple with the color-forming compounds to form a dye image.

The color-formers (couplers) can be incorporated in the emulsions in the customary manner, e.g., by adding a dispersion of the coupler in a water-insoluble but waterpermeable material to the emulsion as indicated previously, or by adding a dispersion of the alkali metal of the coupler in water. Couplers can also be added to the emulsion in crystalloidal materials such as oil-boiling organic crystalloidal materials to produce an oil-like misture which can then be dispersed in water or a binder of colloidal character as well known in the art. (See for example U.S. Patent 2,640,776.) Dispersion of the coupler in a binder can be efiected with the aid of a homogenizer, a colloid mill, or the like; and dispersions can be stabilized by the addition of emulsifying agents also well known in the art.

sensitizing dyes of the type previously indicated normally are added to the emulsion before the coupler or coupier dispersion is added. (See for example US. Patent 2,640,776 and 2,407,210.) Typical sensitizing dyes for use in emulsions of the invent-ion have been described in a number of U18. and foreign patents, for example, US. Patents 2,478,366, August 9, 1949; 2,213,238, September 3, 1940; 2,231,658, February 11, 1941; and 2,515,- 913, July 18, 1950.

To further describe the invention, reference will now be made to the following examples.

EXAMPLE I A multilayer photographic element of the type described in Jelley and Vittum U.S. Patent 2,322,027, issued June 15, 1943, was used as the multilayer sensitive element. Separate elements of the type described were given a like exposure to a colored image in theusual manner and processed according to the following procedures in which one of said elements was processed in a conventional manner (Process A) and the second element was processed according to the present invention (Process B).

Process A (70 F.)

Time

Color develop a- 7 min. 30 sec. Wash -15 sec. Fix 4 min. Wash -4 4 min. Bleach 8 min. \Vash 4 min. Fix 4 min. Wash 7 min. Butter 1 min.

Wash 2 sec.

Total time 39 min. 47 sec.

Process B (70 F.)

Time

Color develop 7 min. 30 cc. Wash 15 sec. Acid stop 2 min. Bleach-fix 4 min.

Bleach 4 min.

Wash 7 min.

Buffer 1 .min.

Wash 2 sec.

Total Time 25 min. 47 sec.

The processing solutions had the following to'rmulations:

COLOR DEVELOPER Water ml 950.0 Benzyl alcohol ml 3.8 Sodium sulfite 0 2.] Sodium hydroxide g 0.45 '4 amino N ethyl N (fi-methanesul-fonamidoethyl) meta toluidine sesquisulfate monohydrate g 5.0 Sodium bromide g 0.86 Sodium carbonate (anhydrous) g .2.7 Water to make 1.0 liter. pH 10.75 at 70 F.

FIX BATH Water ml 600.0 Sodium thiosulfate g 240.0 Sodium sulfite g 15.0 Glacial acetic acid g 13.4 Boric acid g 7.5 Potassium alum g 15 .0 Water to make 1.0 lite-r. pH 4.2 at 70 F.

BLEACH BATH Water ml 800.0 Potassium ferricyanide Q g 50.0 Potassium bromide g 20.0 Water to make 1.0 liter. pH 6.5 at 70 F.

BUFFER BATH Water -m1 800.0 Disodium hydrogen phosphate g 8.2 Glacial acetic acid ml; 4.5 Water to make 1.0 liter. pH 5.0 at 70 F. V,

. ACID STOPVBATH Water ml 600.0 Sodium sulfite g 15.0 Glacial acetic acid ml 15.0

\Vater to make 1.0 liter. Adjustment to final pH of 4.2 using acetic acid or sodium hydroxide as required.

Sodium sulfite 15.0 pH 7.0 8.t70F.

In either of the processes of the example; color develop-l merit formed silver, cyan magenta, and'yellow dye densities in the. sensitive layers of the element; and after development in each process, 'ithe emulsion layers were cleared of silver and silver halides, leaving the respective dye densities in situ. V 7

Process A. a conventional process, requirerl'39 minutes,

.47 seconds and employed ten steps including development,

pvhereas processing according to the present invention (Process B) required25 minutes, 47 seconds and employed eight steps. The process of the present invention, in effect, reverses the normal processing order by employ ing a bleach bath'subsequent to a fixing bath to clear the photographic material of silver and silver halide from the emulsion layers. a e

The sensitometrie results of the example are shown in the accompanying drawing in which FIG. 1 shows the sensitornetric curves obtained from the material processed according to Process A and 'FIG. 2 shows the sensitometnic curves obtained in a comparable element processed according to Process B.

More particularly, in FIG. 1, sensitometric curve shows the integral cyan dye density of the prowssed element as measured in a Well known manner on an Eastman Electronic densitometer using a tungsten light source and red-light transmitting filter. Sen-sitometric curves 11 and 112 show the integral magenta and yellow dye densities,-

respectively, as measured in like manner using a greenlight transmitting "filter .for the magenta dye density determination and a blue-light transmitting filter for the yellow dye density determination.

In 1 16. 2,

sensitometric curves

13, 14, and show, respectively, the cyan, magenta and yellow integral dye densities obtained in like manner in the element processed according to Process B. The density measurements were made employing, respectively, red-, greenand blue-light (transmitting sources as in the 'FIG. 1 determination. The retention of silver in the elements processed in l the present example was in each' case 1 mg. or less p r square foot for theelements processed according to either of Processes A or B as determined in a well known manner, for example, by X-ray'fiuorescence analysis. The ele- .rnents .usedin the present example contained in excess of 200 mg. of silver per square foot prior to processing.

EXAMPLE II Separate multilayer photographic elements of the type used in Example I 'wereexposed to a multicolored image in a well known 'manner after which one strip was processed according to a conventional process (Process C) and the second strip was processed according to the process of the present invention (Process D).

Process C 7 :Min.

; Color develop 12 Benzyl alcohol ml 12.6 Sodium heXametaphospha-te g 2.0 Sodium sulfite g 2.1 0 Sodium carbonate g 26.8 Potassium bromide g 0.48 Sodiumchloride g 0.70

r G. Boric acid 5.0 Potassium alum 24.0 Sodium thiosu iate u 223.0 Sodium. bisulfite 12.0 Sodium acetate (desiccated) 14.0 Sodium citrate (desiccated) 1.7 Water to 1.0 liter. v pH 4.40 at F.

BLEACH BATH 1 G. Sodium nitrate V 45.0 Potassiumrferricyanide r225 Potassium bromide 8.2 Boric acid V 7.5 Borax 0.97 7 Water to 1.0 liter.

pH 7.30 at 75 F.

HARDENER-FIX BATH G. Glacial acetic acid 15.0

Zinc sulfate 7 l i V 7.5 Sodium citrate V 2.5 Zircotan 0.46 Sodium bisulfite 17.9 Boric'acid r 17.2 Potassium. alum 35.5 "Sodium thiosulfate 1.67.7 Water to 1.0 liter. 7 V a a pH 4.40 at 75 F. V

' FORMALIN-HARDENER BATH. Calgon (sodium hexametaphosphate) g 0.75 Sodium carbonate g 8.8 'Formaldchyde (37% solution) ml 25.5

Water to 1.0 liter. 0

f ProcessD Color develop l Acid-hardener bath' l 2 Bleach-fix p '2 Bleach '4 Wash 8 Buffet} 3 Total time 29 The processing solutions not previously disclosed had the following formulations:

.coLo R DEVELOPER Hydroxylamine sulfate g 2.1 4 amino N ethyl N-(,B-rnethanesulfonamidoethyl) -rn et a-toluidine sesquisulfate monohydrate g 4.2 Water to 1.0 liter. pH 9.96 at 75 STOP BATH Glacial acetic acid ml 17.0 Sodium sulfite g 20.0 Water to 1.0 liter. pH 4.64 at 75 F.

mnscu FIXING BATH The processing time for the standard process (Process C) of the example was 43 minutes as compared to a 29- minute process time for Process D. Substantially the same sensitometric results and silver retention were obtained in either case. Each element contained an excess of 200 mg. of silver per square foot prior to processing.

EXAMPLE HI Separate strips of a photographic material of the type described in Jelley et al. US. Patent 2,322,027 coated on a paper support were exposed to a multicolored positive transparency in the usual manner and processed separately according to the following procedures, in which Process E is a standard reversal process and Process F is a reversal process of the present invention.

Process E Presoak 2 min. Drain 2 min. First developer 6 min. First stop 3 min. Wash 7 min. 15 sec. Reversal exposure:

Color develop 7 min. 15 sec. Second stop 3 min. Wash 7 min. 15 sec. Bleach 7 min. 15 sec. Wash 7 min. 15 sec. Hardener-fix 7 min. 15 sec. Wash 14 min. 30 sec. Stabilizer 1 min.

Total processing time 75 min.

Process F Presoak 2 min. Drain V 2 min. First developer 6 min. First stop 3 min. Wash 7 min. 15 sec. Reversal exposure:

Color develop 7 min. 15 sec. Second stop 3 min. Bleach-fix 4 min.

Bleach 4 min. Wash 14 min. 30 sec.

Stabilizer 1 min.

Total processing time 54 min.

Processing solutions used in the present example which have not been previously disclosed herein had the following formulations:

FIRST DEVELOPER N-methyl-p-aminophenol sulfate g 0.9 Sodium sulfite g 8.0 Hydroquinone g 2.35 Potassium bromide g 0.55 Sodium metaborate (8H O) g 25.5

6-nitrobenzimidazole nitrate (0.5% solution) ml 12. Water to 1.0 liter. pH 10.03 at 75 F.

FIRST lSTO'P BATH Sodium acetate 8.0 lacial acetic acid 19.0

Water to 1.0 liter. (Adjust to pH 3.7 at 75 F. using sodium hydroxide.)

SECOND STOP BATH Potassium iodide 2 0.2 Sodium bisulfite g 15.0 Glacial acetic acid m1 20.0 Potassium alum g 30.0

(Adjust to pH 3.0 using sodium hydroxide or sulfuric acid as required.)

BLEACH BATH.

The process time in the present example was shortened from 75 minutes to 54 minutes and resulted in reduced stain density according to the following data.

Stain Density Red Green Blue- Process E 22 22 26 Process F 18 17 18 Change in stain density 4 5 9 The stain densities were measured in a well known manner by reflection densitometry in which the integral dye densities in the cyan, magenta, and yellow were determined using red-, greenand blue-transmitting filters, respectively.

In the present process, good image densities are obtained presumably since the invention permits the use of a final bleach which oxidizes leuco dye present to full color intensity. The photographic materials of the previous examples contained in excess of 200 mg. of silver per square foot. The silver retained after processing was equal to or less than the silver retention in conventionally processed elements which involved more time and a greater number of steps. Photographic materials having from 200 to about 600 mg. of silver per square foot can be processed to an optimum photographic result by way of the present invention.

The invention has been described in detail with parjticular referencev to preferred embodiments thereof but it will be understood that variations and modifications jean be eflected Within the spirit and scope of the inven-' ;tion as described hereinabove and as defined in the ap- .spen-ded claims. i

Q We claim: 1.,In the color processing of an'exposed photographic silver halideemulsion' layer containing a color coupler fthat has been color developed to form a dye image, the improvement which comprises treating the said color Ideveloped emulsion layer with an aqueous solution conftaining ferric chloride and a thiosulfate silver halide :solvent and thereby solubilizing'and'rernoving silver and .silver halide from said emulsion layer, and thereafter further treating the resulting emulsion layer with an aqueous solution containing a ferricyanide silver oxidizi12 agent and thereby oxidizing leuco dye in said emulsion layer to full color" intensity; I g

2. In the color processing of an exposed photographic silver halide emulsion layer containing a color coupler that has been color developed to form" a dye irnage, the improvemnt which comprises treating the said color developed emulsion layer with an aqueous solution containing ferric chloride and an alkali metal thiosulfate and thereby solubilizing and removing silver and silver halide from said emulsion layer, and thereafter further treating the resulting emulsion layer with an aqueous solution containing an alkali metal ferricyanide and thereby oxidizing leuco dye in said emulsion layer to the full color intensity of the dye.

i2 :3. In the color processing of an exposed photograehic silver halide emulsion layer containing a color coupler that has been color develcpedto form a dye image, the.

improvement whichcomprises treating the said color developed emulsion layer with an aqueous solutionvcon taining" ferric chloride, ethylenediamine' tetraacetic. acid," sodium thiosulfate and sodium sulfite'and thereby solubilizing and removing silver and silver halide from said emulsion layer, and thereafter further treating the resulting emulsion layer with an aqueous solution containing potassium ferricyanide andthereby oxidizing leuco dye in saidemulsion layer to full color intensity.

4. The process as described in claim 1 wherein the silver halide emulsion layer contains in excess of 20-0 mg. of silver per square foot.

References Cited by the Examiner V UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner.

LOUISE P. QUAST, Examiner.

Claims

1. IN THE COLOR PROCESSING OF AN EXPOSED PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER CONTAINING A COLOR COUPLER THAT HAS BEEN COLOR DEVELOPED TO FORM A DYE IMAGE, THE IMPROVEMENT WHICH COMPRISES TREATING THE SAID COLOR DEVELOPED EMULSION LAYER WITH AN AQUEOUS SOLUTION CONTAINING FERRIC CHLORIDE AND A THIOSULFATE SILVER HALIDE SOLVENT AND THEREBY SOLUBILIZING AND REMOVING SILVER AND SILVER HALIDE FROM SAID EMULSION LAYER, AND THEREAFTER FURTHER TREATING THE RESULTING EMULSION LAYER WITH AN AQUEOUS SOLUTION CONTAINIG A FERRICYANIDE SILVER OXIDIZING AGENT AND THEREBY OXIDIZING LEUCO DYE IN SAID EMULSION LAYER TO FULL COLOR INTENSITY.