US2607686A

US2607686A - Process of obtaining cold sepia tones

Info

Publication number: US2607686A
Application number: US122093A
Authority: US
Inventors: Ira B Current
Original assignee: General Aniline and Film Corp
Current assignee: GAF Chemicals Corp
Priority date: 1949-10-18
Filing date: 1949-10-18
Publication date: 1952-08-19
Anticipated expiration: 1969-08-19

Description

Aug. 19, 1952 B CQRRENT 2,607,686

y PROCESS 0F OBTAINING COLD SEIA TUNES Filed 06f. 18, 1949 WA VELENGTH /Nv M/LL/M/GRONS INVENTOR /PA f8. CURRENT Patented Aug. 19, 1952 PROCESS oF OBTAINING coLD f ToNEs j SEPIA .Y if

ra B. Current, Binghamton, N. Y., assigner to General Aniline & Film Corporation, New York, v N. Y., Ya corporation of Delaware Application october 1s, 1949, 'serial No. 122,993 j solaims. (cias-488) This invention relates to the toning of vdeveloped photographic prints andr particularly to an improved process of obtaining cold sepiatones by sulfur or selenium toning of developed chloride and chloro-bromide emulsions. Y

It is known in the photographic art that metallic silver, which forms the image of a photographic print or transparency, can be replaced with a compound of silver or other metal, such as sulfur, selenium, gold, tin and the like, by the toning process. The most generally used toning process consists of converting the metallicsilver to silver sulfide or silver selenide to produce what are commonly known as sepia prints which range in color from a yellowish brown to ashade approaching purple. vsulfide and selenide toning methods may be either direct, in which `the silver image is converted at once into an imager of silver sulfide or silver selenide, or indirect, in which the silver image is first converted to a silver halide by bleaching, and then transformed into a sulfide or selenide image in a bath containing soluble sulfide or selenide.

The color of a sulfide-toned printv depends upon the sizes and structures of the grains of which the image is composed. A coarsegrained structure in the original silver print generally gives a tonev tending toward the purple.,while a fine grained print-generally produces a toned print of a yellowish brownshade. Forthis reason, both the nature `of the emulsion withwhichthe print is made, and the processing procedure used in making a silver print have a bearing upon the color of theprint after toning has been carried out. For example, the development of the silver print has a very important effect upon the color of the toned print. If a print is overexposed and underdeveloped, the grain structure is finer and the color of the toned print tends toward 'the yellow.

Considerable time and effort have been exthe prints should be developed prior to toning in a developer containing a specified amount of a soluble bromide-'for a fixed period of time. As a consequencey of this understanding, several print developers containing specified amounts of a soluble bromide have been devised for various positive emulsions. For bromide and fast chlorobromide papers-ian Amidol (di-hydrochloride of 2,4-diaminophenol) developer containing one gram of potassium bromide is generally used. A Metol-glycine-hydroquinone (p-methylaminophenol sulfate, p-hydroxyphenylglycine, and hydroquinone) developer containing from 3 to 4 grams of potassium bromide is generally used for chloride and chloro-bromide papers, whereas for some chloride and slow chloro-bromide papers, a Metol hydroquinone developer containing from 11A; to 2 grams of 'potassium bromide is generally used. For some bromide and chloro-bromide papers, a glycine-hydroquinone developer containing as high asA 4 grams of potassium bromide has been recommended.

In developing positive chloride and chlorobromide emulsions with developers normally used, i. e., those containing from 0.5-4 grams of potassium bromide per liter, warmer tones are obtained after sulfur or selenium toning. Despite the fact that these emulsions are available in a wide range of speeds, from the slow chloride type to the fastest papers, substantially equal in speed to the fastest bromides, they all may yield upon development with the recommended print dev velopers, followed by sulfur or selenium toning,

pended by investigators in devising satisfactory y methods of obtaining uniformly the` desired shades in sulfide and 'selenide toned. prints. In the field of portrait and pictorial photography, the positive emulsionsV used have lbeen formuflated to produce only a relatively warm tone upon development. However, many photographers also desire to use the same paper for sepia toning, but are disappointed by the extremely warm or yellowish sepia tones obtained, despite the fact that bromide emulsions tend to produce somewhat colder tones than either chloride or chlorobromide emulsions.

f It' has always been taught by the art that for greatest uniformity of color and depth of tone,

. inafter. f

prints of warmer than desired character. It is an object of the present invention to providea 'method whereby cold sepia tones are;ob

tained by the toning of chloride and chlorobromide emulsions. Other objects and advantages will appear here- I havefound that contrary to recognized Vunderstandings yand established procedures, chloride I and chloro-bromide positive' emulsions, which normallyv yieldv warm tones upon sulfur orv selenium toning, yield colder sepia tones by first developing the'exposed chloride and chlorobromide positive emulsion with any black and white print developer containingfrom 20 to 80 grams 1of potassium vbromide per liter of developer.,` With normal orv slightly increased developingtime, the prints are altered so that alvmost any degree of colder (deeper brown) sepia and even bluish-black tones are obtained on sulfur or selenium toning. This unexpected result appears to be due to the'high concentration of potassium bromide in the developer, which posgrowth (compared to an Ostwald ripening effect),

to give a tone eifect more nearly approaching that available from a bromide paper. The amount of potassium bromide to be added to the developer is governed by the kind of paper selected for making the print and the color tone desired. vFor a slow chloro-bromide and' a fast.

chloro-bromide or a chloride paper of moderate speed, as little as 20 grams per literof potassium bromide is sufficient to produce a noticeable effect.V

`tones they represent become. :across With no ups or downs would represent a practically neutral or gray tone.

the tone is represented by the shape of the curve after development from 4 to 8"minutes followed by toning. A'concentration of 50 grams per liter of potassium bromide has been found to produce satisfactory cold tones after toning. Above 80 grams per literof addedfpotassium bromide, the restraining action may be so Ygrea-,tl that Vthae effector the'conversion of'the halide in the paper cannot bei realized and a Warmer than normal tonemay result. The exact limits of potassium bromide concentration are dependent, therefore, uponpthe type of emulsion, i.V e., Whethera chloride or a chloro-bromide; emulsion, the .desired tone, and the developing time, all of whichcan be very'readily ascertained by simple trial experimentsK y f The .developers which may be vused vinaccord-V ance'WithLthe present invention are thosewhich are normally employedffor` Adeveloping' out .positive silver halide emulsions. As illustrative examples of vthereducing agentsY contained in such developers, the following are given: (a) p-liethylamincphelnol sulfate and hydroquinone Y (5) G lycin (p-hydroxyph'enylglycine) Y (c) lAdurol (2#brume1Adihydroxybenzene)' (d) Eikonogen V(hydrated sodiumaminoA naph-v Athol Sulfonate) i n (e) Amidol (2;4-diaminophen'ol dihydrochloride) ('f) Chlorhydro'quncne (2.-chloro-1fi-dihydroxybenzene) Print developers containing the -foregoingree ducing orV developing ag ents are availablein photographic literatureand need not be Arepro,- duced herein.

As pointed out above, .the developing time of the exposed printmay. vary from. 4 to 8 minutes. The usual. developing/,time With developers of this type, withoutfthe 4higli concentration Lof potassium bromide, normally usedfor-'developing exposed positive. emulsions. varies from; .L1/2; to 15 minutes. Withthesame developers containing from 20y to 80 grams of potassium bromide-a minimum developing.. time of. about. 2, minutes may be necessary to yield satisfactory results. The developing time must, in some cases fdepending. .uponf the typev of vprint paper, be .extended frornV to v1() minutes to' overcome the restraining effectief the potassium br'omidegfothervvise Vthe result may yield. .warmer-.l tones .thanswould be obtained Withoutv the bromide addition. This makes vthe developingbtirnelan .important variable When using, prior toltoning, a developer cone taining a high concentration.v of potassium bromide, but Vif .it isextended enough, Vusually not more than 8V to 1'01 minutes, reasonablyV repro` ducible colder toningresults will be obtained warm tone printingpapers.V f

The present invention.. is. illustratedV by f thev accompanying drawing-in whichFigs. lfand 2` represent spectrophotometric refiectanceE-curves 4 indicating the relative proportions of light of different wavelengths that are reected from the toned areas. In other words, the curves are graphic presentations of the relative color of the tones at an arbitrariiy chosen medium density (0.5) at Wavelength 400 at Which the start of the -curves are selected. Although these curves do not show the `eiects of higher and lower densities which also influence the color of the tone prints,

vthey serve, however, to show the relative toning effects. The higher the right hand part of the curvesextend, the morereddish or warmer the A curve straight The color of land even relatively minor variations in the curve shape may be detected in the actual print by an experienced eye.

These curves were obtained by adjusting toned photographicprint Wedges in thespectrophotometerf until the ton'edfdeposit-gave a reilectance reading of Y3 O at` a Wavelength,ofA 400 millimicrons..

Fig. 1 indicates'the natureofthetones obtained on a slow chlorof-bromide tpaperA withl a two r`minute developmentiin a high energy` devel,- oper containing no potassium bromide and 20 and 80 grams per. liter-respectively, andthe subsequent. conversion of the Asilver image intothe silver sulfide image.; Y

Fig s2..illustrates.;the` toning Veiect on a fast chloro-bromide paper. resulting fromI 8-rninute development in alovv energy developer containing f no potassium bromide andff andai) gramsof bromide: projectionpaper'of moderatespeed were exposed;v Them-sti. paper: was,developed in a developer solutiorrofz. the following composition for .5 minutes: at 68? F.: f

Y prepared. as 'above;-except that the developing Frnithese lcurves, it will be.observed .that/the addition vof 20 .and y8l) 'grams 'ofI potassiumA .bromide. respectively, per literof-'developer produces excellentcoldertones when followed by direct sepia toning.

ilExample-II A lTh'ree'shee'tsl'of al fast chloroebromideemulsion projection paper were individuallyv-exposed through a-.nega'tiva The "first .exposed print was developed for 8 minutes at 682 C in a developer solutiofpf the following composition: Hotjwater}('l25 F. or 52 C.) 1;.; cc l. A1750 The second and third"ei'qiolsedf` papers :were developed in tw'or separate developing solutions prepared as above, except that thel developing solutions contained in addition 20 and 80 grams of potassium bromide per liter, respectively.

After short-stopping, fixing, washing, and drying, the developed prints were toned :for 10 minutes at 72F. in a solution prepared as follows:

100 grams of sodium sulte are dissolved in a smallv amount of Water, then 10 grams of powdered selenium metal dissolved in this solution, and the volume -brought up to 1 liter. The clear part of the solution may be decanted or ltered from any sediment remaining and used as a direct'toning solution.

The toned prints were washed for minutes in flowing water and then dried.

Spectrophotometric curves of the resulting three images, at a density of about 0.5, were obtained as illustrated in Fig. 2. These kcurves illustrate the somewhat less cold toning effects resulting from the development with bromide additions.

In lieu of the developing solutions of the foregoing examples the following developer solution may be employed to yield the same colder tones when followed by direct sepia toning:

Hot water (125 F.) cc 750 p-Methylaminophenol sulfategrams.. 5 Sodium sulflte do 40 Hydroquinone ..do 6 Potassium bromide do 50 Sodium carbonate (monohydrate) do 40 Water to make 1 liter.

Example III Three sheets of chloro-bromide projection paper were processed up to and including the washing step described in Example I.

After washing the prints were bleached for 5 minutes in a solution of the following composition? Potassium ferricyanide grams-- 50 Potassium bromide do 10 Water to make 1 liter.

The bleached prints were washed for 5 minutes and toned, i. e., redeveloped. in a 1% solution of sodium sulfide in water.

'I'he toned prints were thoroughly `washed in water for 30 minutes and dried. Prints of excellent cold sepia tone were obtained.

-An optional hardening treatment with an aqueous chrome alum solution may be used on the toned prints prepared as above after some preliminary washing so as to remove most of the 6 sodium sulde absorbed bythe emulsion layer;v Once a particular printgdeveloper containing from 20 to 80 grams of potassiumfbromide-,per literhas beenfound whichgives the desiredsepia tones,fa1l 'the'steps e., developer formula and concentration "of 'potassium bromide o'uldfbe carefully standardized and made yuniform from` one tim-e tothe next, and frequentv renewalo all processing solutions will insurev .uniformity of tones from .day to day. .Onthe otherifhandgthe. factorseifecting the .sepia tones maybe-putte, an' advantage.. in securingalmostany.- degreefo'f. warmth and tone,. 'particularly the1addition:of potassium bromide ranging .from v220 to y80, grams per liter to an energetic developer with increased deveiopirlgtiine, i. e.; frcm'at 1p mimiteswiiicn can' provide" -direct sepia tones, 'considerably colder than Flemish tones available 'from the' same paper with normal print developer andvde-V veloping time1`- :ff nl -;'..'1,.": u f f IWhile I have herein vidiscl'osed the preferred embodimentslof my invention,vI doV not desirelt'o limit myself solely to the specific examples since it will lbe readily apparent to those skilled in the art that the precise ratios of potassium bromide and the nature of the reducing agent in the print developer may be varied. Any other reducing materials having equivalent properties may be employed without departing from the spirit and scope thereof. Accordingly, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process of obtaining cold sepia tones by toning warm toned positive printing papers of the group consisting of chloride and chloro-bromide papers which consists of exposing and developing said papers with a photographic developer for positive silver halide emulsions comprising an aromatic silver halide developing agent and from 20 to 80 grams of potassium bromide per liter, fixing and washing the developed print, and subsequently toning it with a toner selected from the group consisting of sulfur and selenium toners.

2. A process of obtaining cold sepia tones by toning a warm toned silver chloride emulsion positive printing paper which consists of exposing and developing said paper with a photographic developer for positive silver halide emulsions comprising an aromatic silver halide de-` veloping agent and from 20 to 80 grams of potassium bromide per liter, fixing and washing the developed print, and subsequently toning with a toner selected from the group consisting of sulcomposition;

Hot water F.) cc 750 p-Methylaminophenol sulfate grams 5 Sodium sulte do 40 Hydroquinone do 6 mamas Henney & Dudley. Handbook of Photpga-rzrfw McGraw-Hill, 1937,*p. 369.

Claims

1. A PROCESS OF OBTAINING COLD SEPIA TONES BY TONING WARM TONED POSITIVE PRINTING PAPERS OF THE GROUP CONSISTING OF CHLORIDE AND CHLORO-BROMIDE PAPERS WHICH CONSISTS OF EXPOSING AND DEVELOPING SAID PAPERS WITH A PHOTOGRAHIC DEVELOPER FOR POSITIVE SILVER HALIDE EMULSIONS COMPRISING AN AROMATIC SILVER HALIDE DEVELOPING AGENT AND FROM 20 TO 80 GRAMS OF POTASSIUM BROMIDE PER LITER, FIXING AND WASHING THE DEVELOPED PRINT, AND SUBSEQUENTLY TONING IT WITH A TONER SELECTED FROM THE GROUP CONSISTING OF SULFUR AND SELENIUM TONERS.