05/358935

02/18/1975

05/10/1973

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Delaware Photographic Products, Inc. (Buffalo, NY)

430/419

430/451, 430/465, 430/456, 430/458, 430/427, 430/437

G03C5/38; G03C5/30; G03C5/38

96/61M,66R,66.3

3615513	INHIBITION OF SILVERING IN PHOTOGRAPHIC PROCESSING SOLUTIONS	October 1971	Haist et al.
3730716		May 1973	Land

Photo Lab-Index, Morgan & Morgan, Inc. Publ., p. 3-231 - 3-233, 1971..

Kelley, Mary F.

Clarence A. O'Brien & Harvey B. Jacobson

1. An aqueous composition for the combined developing and fixing of exposed silver halide photographic emulsions, having a pH in the range 9.5 - 10.75, comprising the following ingredients in the weight proportion ranges indicated per liter of composition: ##SPC4##

2. A composition, as claimed in claim 1, wherein said 3-pyrazolidone developer is selected from developing agents having the following chemical structure: ##SPC5##

3. A composition, as claimed in claim 2, wherein said 3-pyrazolidone is

4. A composition, as claimed in claim 1, wherein said enediol is selected

5. A composition, as claimed in claim 1, wherein said aminophenol developer

6. A composition, as claimed in claim 1, comprising the following ingredients in the weight proportion ranges indicated per liter of composition: 3-pyrazolidone developer 2 to 4 grams dihydroxybenzene developer 8 to 12 grams aminophenol developer 1/2 to 2 grams enediol developer 3 to 7 grams inorganic sulfite preservative 20 to 75 grams alkaline agent 3 to 7 grams restrainer 1/4 to 11/4 grams fixing agent 70 to 95 grams.

7. A composition, as claimed in claim 1, wherein said dihydroxybenzene is hydroquinone, said 3-pyrazolidone is 1-phenyl-3-pyrazolidone, said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid, and said aminophenol is 2,4-diaminophenol dihydrochloride.

8. A composition, as claimed in claim 7, wherein said inorganic sulfite

9. A composition, as claimed in claim 7, wherein said alkaline agent is

10. A composition, as claimed in claim 7, wherein said restrainer is

11. A composition, as claimed in claim 7, wherein said pH is in the range

12. A composition, as claimed in claim 7, further including at least one of the following additional ingredients:

13. A composition, as claimed in claim 12, wherein said additional ingredient is a grain reducer selected from sodium and potassium

14. A composition, as claimed in claim 12, wherein said additional

15. A composition, as claimed in claim 12, wherein said additional

16. A composition, as claimed in claim 12, wherein said additional

17. A composition, as claimed in claim 15, wherein said water softening

18. An aqueous composition for the combined developing and fixing of exposed silver halide photographic emulsions comprising the following ingredients in the weight proportions indicated per liter of composition:

19. A process for simultaneously developing and fixing an imagewise exposed silver halide emulsion comprising contacting said emulsion with an aqueous monobath composition having a pH in the range of 8 - 9.5, said monobath comprising the following ingredients in the weight proportion ranges indicated per liter of composition: ##SPC6##

20. A process, as claimed in claim 19, wherein said 3-pyrazolidone developer is selected from developing agents having the following chemical structure: ##SPC7##

21. A process, as claimed in claim 19, wherein said dihydroxybenzene is hydroquinone, said 3-pyrazolidone is 1-phenyl-3-pyrazolidone, said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid and said aminophenol is 2,4-diaminophenol dihydrochloride.

22. A process, as claimed in claim 21, wherein said pH is in the range 9.8

23. A process, as claimed in claim 21, further including at least one of the following additional ingredients:

24. A process, as claimed in claim 23, wherein said monobath composition comprises the following ingredients in the weight proportions indicated per liter of composition:

25. A process, as claimed in claim 19, further including the step of

26. A process, as claimed in claim 25, wherein said monobath temperature is

27. A process, as claimed in claim 19, further including the step of rinsing the developed and fixed emulsion in an aqueous hardening bath.

28. A process, as claimed in claim 27, wherein said hardening bath includes a silver halide emulsion hardener selected from acid alum and aldehyde

29. A process, as claimed in claim 28, wherein said hardening bath comprises the following ingredients in the weight proportions indicated per liter of hardening bath:

30. A dry mixture, all ingredients of which are adapted to be admixed and dissolved in water to produce a solution having a pH in the range 9.5 to 10.75 for the combined developing and fixing of an exposed silver halide photographic emulsion comprising: ##SPC8##

31. A dry mixture, as claimed in claim 30, wherein said dihydroxybenzene is hydroquinone, said 3-pyrazolidone is 1-phenyl-3-pyrazolidone, said enediol is selected from the group consisting of tetramethyl reductic acid and ascorbic acid and said aminophenol is 2,4-diaminophenol dihydrochloride.

32. A process, as claimed in claim 27, wherein said hardening bath comprises the following ingredients in the weight proportions indicated per liter of hardening bath:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to chemical compositions for the combined developing and fixing of silver halide photographic emulsions.

2. Description of the Prior Art

Compositions for the combined developing and fixing of silver halide photographic emulsions (monobaths) have conventionally employed numerous silver halide developing agents. Exemplary of these agents are 1-phenyl-3-pyrazolidone (commonly called Phenidone, a registered trademark of Ilford Ltd.), 2,4-diaminophenol dihydrochloride (Amidol), hydroquinone and ascorbic acid. In addition, various combinations of these agents are well known for use in conventional developer formulations. Thus, for example, U.S. Pat. No. 3,276,875 teaches the use of Phenidone in combination with each of hydroquinone, amidol and ascorbic acid, individually, and with a mixture of hydroquinone and ascorbic acid. Monobaths have also employed combinations of the various well known developing agents, as shown, for example, in U.S. Pat. Nos. 2,875,048 and 2,751,300 (Phenidone-ascorbic acid), U.S. Pat. Nos. 3,240,603 and 3,232,761 (Phenidone-hydroquinone) and Canadian Pat. Nos. 670,962 and 682,111 (Phenidone-hydroquinone and Phenidone-amidol).

However, every known monobath employing combinations of the aforementioned developers is a special purpose monobath in the sense that its composition is formulated to make it particularly effective in the developing and fixing of only certain emulsions, and reformulation of the monobath is required for it to be equally effective with other emulsions. While these special purpose monobaths could, of course, be employed with other emulsions, their ability to produce satisfactory images therewith is substantially reduced. In his Monobath Manual at page 45, Grant Haist explains the inability of known monobaths to produce satisfactory results with more than one emulsion by noting that "commercial monobaths are often compromise formulations that . . . fail to give the best results possible with each film or paper" and that "the general-purpose monobath usually fails to please anybody but the uncritical."

Haist recognizes that there exists no single monobath capable of producing satisfactory results with all emulsions without reformulation. He suggests, at page 51, a general purpose monobath, the MM-1 monobath, which supposedly produces satisfactory results with all films by adjusting the mono-bath pH for each film. While it is true that pH adjustments of the MM-1 mono-bath with either sodium hydroxide or glacial acetic acid produce images having acceptable contrasts with various films, this can be accomplished only at the expense of speed loss. With the exception of Verichrome Pan and Royal-X Pan for which MM-1 apparently works without adjustment, pH adjustment is accompanied by speed losses of from 1/3 to 1 stop.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a monobath which is effective with all films and which require neither reformulation nor pH adjustment to produce satisfactory images.

It is another object of this invention to provide a monobath composition which is effective for developing and fixing all emulsions by suitable changes in agitation and temperature.

It is still another object of this invention to provide a process of developing silver halide emulsions by employing a single monobath composition and varying only agitation and temperature for each emulsion.

Other objects and advantages will become apparent from the following description and appended claims.

Briefly stated, in accordance with the aforesaid objects, the present invention provides a monobath composition comprising four developing agents -- (a) a 3-pyrazolidone; (b) an aminophenol; (c) a dihydroxybenzene; and (d) an enediol -- and a silver halide solvent. Preferably, the developing agents employed are Phenidone, amidol, hydroquinone and ascorbic acid, respectively, and the silver halide solvent is sodium, potassium or ammonium thiosulfate or thiocyanate. In another embodiment, the present invention comprehends a process for developing and fixing silver halide film by contacting the film with an alkaline monobath comprising a developing agent selected from each of the aforementioned classes and a silver halide solvent. By varying the monobath temperature and the extent of agitation, the monobath compositions of the present invention are effective in producing satisfactory images on all film emulsions without film speed loss.

DETAILED DESCRIPTION OF THE INVENTION

The present invention, in its broadest form, provides an alkaline monobath composition containing four developing agents and a silver halide solvent, which monobath is effective for all films by suitable changes in agitation and temperature.

The silver halide developing agents employed in accordance with the present invention are selected, one each, from the following classes of agents:

a. 3-pyrazolidones;

b. dihydroxybenzenes;

c. aminophenols (including diaminophenols); and

d. enediols.

The 3-pyrazolidone silver halide developing agents have the general structure ##SPC1##

in which the R groups each represent various substituents such as hydrogen, alkyl or aryl groups. For example, R ₁ can be hydrogen, a group such as alkyl preferably containing from 1 to 4 carbon atoms, or an aryl group of the benzene or naphthalene series substituted or not; and R ₂ , R ₃ , R ₄ and R ₅ can be hydrogen atoms, groups such as an alkyl group preferably of 1 to 4 carbon atoms, or an aryl group such as phenyl.

1-phenyl-3-pyrazolidone (Phenidone) is the preferred member of the 3-pyrazolidone class of agents for use in the present invention. Phenidone is preferred because it is commercially available in large quantities while other known, related developing agents having similar structure and characteristics are not widely available. The following compounds are representative of 3-pyrazolidone silver halide developing agents which are useful in the monobath compositions of the invention:

1. 1-phenyl-3-pyrazolidone

2. 1-p-tolyl-3-pyrazolidone

3. 5-phenyl-3-pyrazolidone

4. 5-methyl-3-pyrazolidone

5. 1-p-chlorophenyl-3-pyrazolidone

6. 1-phenyl-5-phenyl-3-pyrazolidone

7. 1-m-tolyl-3-pyrazolidone

8. 1-phenyl-5-methyl-3-pyrazolidone

9. 1-p-tolyl-5-phenyl-3-pyrazolidone

10. 1-m-tolyl-3-pyrazolidone

11. 1-p-methoxyphenyl-3-pyrazolidone

12. 1-acetamidophenyl-3-pyrazolidone

13. 1-phenyl-2-acetyl-4,4-dimethyl-3-pyrazolidone

14. 1-phenyl-4,4-dimethyl-3-pyrazolidone

15. 1-m-aminophenyl-4-methyl-4-propyl-3-pyrazolidone

16. 1-0-chlorophenyl-4-methyl-4-ethyl-3-pyrazolidone

17. 1-m-acetamidophenyl-4,4-diethyl-3-pyrazolidone

18. 1-p-(B-hydroxyethylphenyl)-4,4-dimethyl-3-pyrazolidone

19. 1-p-hydroxyphenyl-4,4-dimethyl-3-pyrazolidone

20. 1-p-methoxyphenyl-4,4-diethyl-3-pyrazolidone

21. 1-p-tolyl-4,4-dimethyl-3-pyrazolidone

22. 1-(7-hydroxy-2-naphthyl)-4-methyl-4-n-propyl-3-pyrazolidone

23. 1-p-diphenyl-4,4-dimethyl-3-pyrazolidone

24. 1-p-(B-hydroxyethylphenyl)-3-pyrazolidone

25. 1-o-tolyl-3-pyrazolidone

26. 1-o-tolyl-4,4-dimethyl-3-pyrazolidone

27. 3-pyrazolidones as claimed in U.S. Pat. No. 3,284,200 of the general formula ##SPC2##

wherein Z is a divalent aliphatic grouping which, with the carbon atoms in 4 and 5 positions of the pyrazolidone ring, completes a five-membered or six-membered cycloaliphatic ring and R ₁ is an aryl group, e.g., phenyl or naphthyl group. Such aryl groups may be substituted with hydroxy, alkoxy, oxyalkyl, amino, substituted amino, nitro, sulphonic or carboxylic groups or halogen atoms. These compounds include, for example, 1-phenyl-4,5-tetramethylene-3-pyrazolidone, 1-phenyl-4,5-trimethylene-3-pyrazolidone and 1-m-chlorophenyl-4,5-tetramethylene-3-pyrazolidone.

The dihydroxybenzene silver halide developing agents which are useful in the monobath may be hydroquinone, resorcinol or pyrocatechol.

The preferred aminophenol (the term "aminophenol" will be employed hereinafter as generic to amino substituted phenols, including diaminophenols) for use in the present invention is 2,4-diaminophenol dihydrochloride, commonly known as amidol. However, a number of aminophenol compounds can be used in place of the amidol in the monobaths of the present invention. It will be appreciated, however, that amidol is the only member of the class that is manufactured and commercially available in quantity. Exemplary of the aminophenol silver halide developing agents which are useful in the present monobath are the following:

1. p-aminophenol

2. N-methyl-p-aminophenol

3. 2,4-diaminophenol

4. 2,4-diaminoresorcinol

5. 6-methyl-2,4-diaminophenol

6. 5-methyl-2,4-diaminophenol

7. 4-amino-6-methyl-2-methylaminophenol

8. 6-amino-4-methyl-2-methylaminophenol

9. 5-dimethylamino-2-methylaminophenol

10. 1,2,4-triaminobenzene

11. 5-methyl-1,2,4-triaminobenzene

12. 4-hydroxy, 2',4'-diaminodiphenylamine

13. 4,2',4'-triaminodiphenylamine

14. 1,3-diamino-4,6-dihydroxybenzene

It should also be appreciated that the acid salts of any of the foregoing aminophenol agents will likewise be suitable for use in the present monobaths.

The enediol silver halide developing agents which are useful in the present monobath include the following:

1. ascorbic acid

2. d-araboascorbic acid

3. reductic acid

4. enediols as disclosed in U.S. Pat. Nos. 3,615,440 and represented by the formula ##SPC3##

wherein R ₁ , R ₂ , R ₃ and R ₄ each are selected from the class consisting of hydrogen and the radical --CH ₂ R ₅ wherein R ₅ is hydrogen or a monovalent organic radical, selected from the group consisting of amino, cyano, halo, hydroxyl, carboxyl, sulfonyl, alkyl, cycloalkyl, aryl of the benzene or naphthalene series and alkaryl of the benzene or naphthalene series, at least one of said R ₁ , R ₂ , R ₃ and R ₄ being --CH ₂ R ₅ . Tetramethyl reductic acid is one particularly useful enediol.

5. 2-oxytetronic acid

6. 4-aryl-2-oxytetronic acid

7. 4-aryl-2-oxytetronimide

8. isoascorbic acid

The monobath also includes a silver halide solvent which imparts the fixing capability to the composition. Exemplary of suitable fixing agents are sodium, potassium and ammonium thiosulfates and thiocyanates.

Inorganic sulfites, such as sodium or potassium sulfite, are utilized in their well-known role as preservatives for the developing agents. In addition, strongly basic compounds, such as sodium or potassium hydroxide, are employed in sufficient quantity to produce an alkaline composition pH in the range 9.5 to 10.75. Preferably the pH is adjusted to the range 9.8 to 10.3 and most preferably to the range 10 to 10.2. The composition also includes a restrainer and grain reducer such as sodium or potassium bromide.

Table I sets forth a broad embodiment of the monobaths of the present invention.

TABLE I ______________________________________ INGREDIENT CONCENTRATION (g/l) Minimum Maximum ______________________________________ 3-pyrazolidone 1 5 dihydroxybenzene 8 14 aminophenol 1/2 3 enediol 1 10 alkaline agent 3 7 inorganic sulfite preservative 20 75 restrainer 1/4 2 fixing agent 60 110 ______________________________________

In addition, conventional antifoggants, grain reducers (e.g., LiCl or NaCl), solubilizers, stabilizers, toners, buffers, antioxidants, sequestering agents and antisludge agents may be used in the monobaths of the present invention. A particularly preferred grain reducer is sodium or potassium thiocyanate which may be incorporated in the monobath in amounts up to about 21/2 grams per liter. A preferred antifoggant, which also serves as a grain reducer, is benzotriazole in minute quantities up to about 0.1 gram/liter. Whether or not ammonium thiosulfate is employed as the fixing agent in the monobath, it has been found to be a useful optional additive in quantities up to 3 grams/liter above any amount used as a fixing agent to increase development speed and to yield increased density images. It is also noteworthy that where hard water conditions prevail some flocculation may occur in the monobath. To remedy this it is desirable to include up to 2 grams of a water softener or water conditioner per liter of composition. Particularly preferred for this purpose is sodium hexametaphosphate, which may be provided as the commercially available product Calgon, manufactured by the Calgon Corporation.

A preferred form of the present invention is set forth in Table II.

TABLE II ______________________________________ INGREDIENTS CONCENTRATION (g/l) Minimum Maximum ______________________________________ 3-pyrazolidone 2 4 dihydroxybenzene 8 12 aminophenol 1/2 2 enediol 3 7 alkaline agent 3 7 inorganic sulfite preservative 20 75 restrainer 1/4 11/4 fixing agent 70 95 ______________________________________

The following examples are illustrative of preferred monobath compositions which have demonstrated their effectiveness on Tri-X, Plus X, Verichrome Pan and Pan-X emulsions.

EXAMPLE I ______________________________________ Phenidone 3 g/l Hydroquinone 10 g/l Amidol 1 g/l Ascorbic Acid 5 g/l NaOH 5.7 g/l Na ₂ SO ₃ 30 g/l NaBr 1 g/l Na ₂ S ₂ O ₃ . 5H ₂ O 80 g/l Sodium hexametaphosphate 2 g/l H ₂ O to make 1 liter pH 10.15 ______________________________________

When Plus-X was processed with the monobath composition of Example I it was surprisingly observed that the film speed was increased. Specifically, density and contrast were so great that it was necessary to decrease processing temperature to compensate. For example, Plus-X (35 mm) exhibited an E.I. of about 275 when processed by the monobath of this Example at 66°-69° F. for 6 minutes with agitation for the first 15 seconds and thereafter for 5 seconds out of every 30 seconds. Plus-X (120) exhibited a similar E.I. under like conditions when processed for 7 minutes.

EXAMPLE II ______________________________________ Phenidone 3 g/l Hydroquinone 10 g/l Amidol 11/2 g/l Ascorbic Acid 5 g/l NaOH 6 g/l Na ₂ SO ₃ 50 g/l NaBr 1/2 g/l Na ₂ S ₂ O ₃ . 5H ₂ O 85 g/l Sodium hexametaphosphate 2 g/l (NH ₄ ) ₂ S ₂ O ₃ 2 g/l Benzotriazole 0.05 g/l H ₂ O to make 1 liter pH 10.25 ______________________________________

EXAMPLE III ______________________________________ Phenidone 21/2 g/l Hydroquinone 10 g/l Amidol 11/2 g/l Ascorbic Acid 7 g/l NaOH 6 g/l Na ₂ SO ₃ 30 g/l NaBr 0.5 g/l Na ₂ S ₂ O ₃ . 5H ₂ O 80 g/l Sodium hexametaphosphate 2 g/l KSCN 2 g/l H ₂ O to make 1 liter pH 10.25 ______________________________________

Temperature has been found to have a profound effect on the relative rates of developing and fixing with the monobaths of the present invention. For example, it has been noted that as the temperature increases above 70°F the rate of development is greater than the corresponding rate of fixation. However, as the temperature decreases toward and approaches 60°F, the rate of development becomes less than the corresponding rate of fixation relative to the 70°F values. While this type of response is noted with most monobaths, with the monobath of the present invention the response is sufficiently profound to enable temperature to be effectively used as a control on monobath performance. When several monobath compositions within the scope of the invention were tested using Tri-X 35mm film, it was noted that the film showed a one to two f stop variation in density as the temperature of the monobath varied between 65° and 75°F. Furthermore, when Panatomic-X 35mm film was processed using the monobath set forth in Example I, there was at least a one f stop difference in the film when processed at 67°F compared to processing at 75°F.

Moreover, contrary to the generally prevailing notion that monobath performance is relatively insensitive to variations in agitation (see, e.g., Kazen and Wolnick, Photogr. Sci. Eng., 6,241 (1962) and Haist, Monobath Manual (1966), page 66), it has been found that emulsions show varying responsivity, i.e., some greater and some lesser to changes in the mode of agitation during processing with the monobaths of the present invention. However, all emulsions were found to be responsive to agitation changes. This observation, together with the profound temperature effects on development and fixation rates hereinbefore described, can be combined to advantage in utilizing the monobaths of the present invention with all known emulsion films without need to adjust pH or to reformulate for each emulsion.

To establish applicable temperature and agitation parameters for various emulsions a number of monobath compositions within the scope of the invention were tested under various conditions on 35mm Tri-X, Plus-X, Verichrome Pan and Pan-X and on 120 Tri-X, Plus-X and Pan-X. Table III sets forth the optimum processing temperature and time for each emulsion with the monobaths of the present invention to achieve results similar to D-76 conventional development in terms of contrast and density range. In addition, Table III sets forth mean agitation modes for optimum performance of the monobaths with each emulsion. It will be appreciated that the agitation modes are not rigorous, unvarying criteria, but rather are guidelines which, if followed within about a 20 percent permissible variation, will yield consistently satisfactory results.

TABLE III ____________________________________________________________ ______________ FILM FORMAT TEMPERATURE AGITATION TOTAL DEVELOP. TIME ____________________________________________________________ ______________ TRI X 35mm 68-70°F 60 sec then 5 sec/30sec 6 min. PLUS X 35mm 58-61°F 10 sec then 5 sec/60sec 61/2-7 min. VER PAN 35mm 66-68°F 15 sec then 5 sec/30sec 6 min. PAN X 35mm 70-72°F continuous 6 min. TRI X 120 67-69°F 30 sec then 5 sec/30sec 7 min. PLUS X 120 58-61°F 10 sec then 5 sec/60sec 71/2 min. PAN X 120 68-70°F continuous 7 min. ____________________________________________________________ ______________

Emulsion hardening when processing with monobaths has heretofore taken the form of (a) prehardening the emulsion in a hardening solution, or (b) incorporating a hardener in the monobath. Neither technique has been found to be satisfactory. Prehardening is itself time consuming, requiring, for example, 90 seconds using the solution of U.S. Pat. No. Re. 26,601. In addition, following prehardening a thorough rinsing is necessary to avoid prehardener carry-over into the monobath and contamination of the monobath. Incorporation of a hardener into a monobath, whether by design or through inadvertence, as by carry-over, typically causes a loss of emulsion speed and shortens the shelf life of the monobath. For example, upon incorporation of an aldehyde hardener in a monobath a slight discoloration of the monobath evidences an increased rate of monobath oxidation with an attendant loss in development capability. Moreover, break down of the aldehyde hardener itself in the monobath makes it doubtful whether effective hardening can be achieved, particularly where the monobath is prepared and kept on the shelf for 3 to 6 months.

It has been found, contrary to some reported observations (see, Sasai and Mii, Studies on Photographic Monobaths Containing Posassium Thiocyanate, Photographic Science and Engineering, Volume 8, No. 3, pages 270-275 (1964), that hardening following development and fixation, i.e., post-hardening, is effective, not only with the monobath of the present invention but with all monobaths. Not only does post-hardening give good hardening but it neither reduces emulsion speed nor decreases monobath shelf life.

Post-hardening by rinsing the developed and fixed film for about 10-30 seconds with either an acid alum hardener or an aldehyde was found to yield excellent results, as shown in the following Examples which illustrate the use of exemplary hardener rinse solutions.

EXAMPLE IV

Boric Acid 5 g Aluminum Potassium Sulfate 5 g Sodium Bisulfate 5 g H ₂ O to make 1 liter pH adjusted to 4.25

EXAMPLE V

Exemplary of a post-hardener concentrate is the following composition

88% Ethanolamine 140 g Boric Acid 70 g Glacial Acetic Acid 140 g Aluminum Chloride.6H 2 O 80 g Ethylene Glycol 30 g

One ounce of the post-hardener concentrate diluted with water makes 1 quart of rinse solution.

EXAMPLE VI ______________________________________ 85% glutaraldehyde l0 ml H ₂ O to make 1 liter ______________________________________

A glutaraldehyde post-hardener is effective but suffers from the problem that it ages at a much faster rate than other post-hardeners, which may last for years.

It should be appreciated that the post-hardening solutions of Examples IV-VI are merely illustrative of the numerous hardening solutions which are suitable. For example, virtually any known prehardening solution can also be used for post-hardening. In addition, known pH and temperature conditions for prehardening are also satisfactory for post-hardening.

A particular advantage of the monobath compositions of the present invention is the flexibility they allow in commercial packaging configurations to insure prolonged shelf life. For example, in one embodiment the primary monobath ingredients, except for the alkalinity agent and the four developers, are provided in dry powdered form. The alkalinity agent is a separately packaged aqueous concentrate and the developers are provided in powdered, pre-mixed form in a number of individual compartments, each compartment containing sufficient developer to activate, for example, 16 ounces of monobath solution. To use such a configuration, the powdered primary ingredients are dissolved in about 48 ounces of water at 52°C to form a concentrate having a shelf life in a tightly stoppered bottle of at least one year. To prepare and activate the monobath, the pre-measured contents of the alkaline agent package are added to the primary ingredients to adjust the pH to the proper range. Finally, a compartment of powdered developer is opened and admixed with 16 ounces of the alkaline solution to form an activated ready-to-use monobath capable of processing three rolls of 120 film or three rolls of 36 exposure 35mm film.

To exemplify the numerous possible configurations, a typical monobath system in accordance with the present invention is shown in Table IV.

TABLE IV ______________________________________ NaOH aqueous concentrate. BASIC MIX ______________________________________ a. Sodium Sulfite b. Sodium Bromide Base Mix c. Sodium Thiosulfate ______________________________________ Y d. Ascorbic Acid e. Amidol Base Mix f. Hydroquinone Z g. Phenidone ______________________________________

Various configurations of the ingredients of Table IV are possible to contribute to the longevity of the packaged ingredients and assure freshness of the product to the ultimate user.

Configuration 1

the NaOH concentrate is added to 800 mls H ₂ O. Basic mix (2) is then added and when dissolved additional water is added to make 1 liter. Alternatively, Basic Mix (2) may be added in increments to activate only a portion of the diluted NaOh concentrate.

Configuration 2

the NaOh concentrate is added to 800 mls H ₂ O. Base mix (2) Y is then added and the resultant solution stored prior to use at which time it is activated by adding Base mix (2) Z and H ₂ O to make 1 liter. Alternatively, Base mix (2) Z may be added in increments to activate only a portion of the stored solution.

Configuration 3

the NaOh concentrate is added to 800 mls of H ₂ O. Base mix (2) Y and ingredient (2)(d) are then added and the resultant solution is stored prior to use at which time it is activated by adding ingredients (2)(e), (2)(f) and (2)(g) and H ₂ O to make 1 liter. Alternatively, ingredients (2)(e), (2)(f), and (2)(g) may be added in increments to activate only a portion of the stored solution.

Configuration 4

the NaOh concentrate is added to 800 mls H ₂ O. Base mix (2) Y plus ingredients (2)(d) and (2)(g) are then added and the resultant solution is stored prior to use at which time it is activated by adding ingredients (2)(e) and (2)(f) to the solution and H ₂ O to make 1 liter. Alternatively, ingredients (2((e) and (2)(f) may be added in increments to activate only a portion of the stored solution.

Thus the method, composition and packaging of this monobath provide a photographic worker with: (1) a monobath that produces a maximum of shadow detail and full emulsion speed; (2) a primary aqueous mixture that has a shelf life of at least six months to one year prior to activation; and (3) a method of activation that enables the worker to activate the solution only when he needs to process film ensuring a fresh solution. By varying temperature and agitation it is possible to process all commercially available camera films intended for continuous tone photography without the need of pH adjustment or reformulating the monobath due to the inherent differences between different speed films.

While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications can be made by those skilled in the art without actually departing from the scope of the invention. Accordingly, all modifications and equivalents may be resorted to which fall within the scope of the invention as claimed.