Periodate photographic bleaching method without acidic prebath

Color photographic elements are processed with a highly acidic periodate bleaching solution including a rehalogenating agent and a strong acid. Bleaching is carried out after color development without any intervening processing steps, such as an acidic prebath. The processing method provides rapid bleaching without physical defects such as blistering or vesiculation, and minimizes the formation of Dmin.

RELEVANT APPLICATION 
Copending and commonly assigned U.S. Ser. No. 08/947,072, filed on Oct. 8, 
1997 by Sidney J. Bertucci and Eric R. Schmittou, and entitled "Periodate 
Photographic Bleaching Compositions and Methods of Use." 
FIELD OF THE INVENTION 
The present invention relates generally to periodate photographic bleaching 
of color photographic elements without the use of an acidic prebath before 
the bleaching step. 
BACKGROUND OF THE INVENTION 
During processing of silver halide color photographic elements, the 
developed silver is oxidized to a silver salt by a suitable bleaching 
agent. The oxidized silver is then removed from the element in a fixing 
step. 
The most common bleaching solutions are desirably acidic, and contain 
complexes of high valence metal ions, such as ferric ions, and various 
organic ligands. Both the metal ions and the chelating ligands present 
environmental concerns and are the subject of increasing regulatory 
scrutiny. Thus, a primary desire in this industry is to design bleaching 
compositions that are more compatible with the environment, with reduced 
use of high valent metal complex bleaching agents. 
Bleaching solutions containing peroxide, or peracids such as persulfate, 
perborate, perphosphate, percarboxylic acid or percarbonate as bleaching 
agents offer an alternative to the ferric complex bleaching solutions. 
They are less expensive and present lower chemical and biological demands 
on the environment since their by-products can be less harmful. A number 
of such compositions have been explored, but to date they have not found 
wide acceptance in the trade for various reasons. 
Various peroxide and peracid bleaching solutions are described, for 
example, in U.S. Pat. No. 5,318,880 (English et al), U.S. Pat. No. 
5,464,728 (Szajewski et al), U.S. Pat. No. 5,508,151 (O'Toole et al) and 
U.S. Pat. No. 5,521,056 (Buchanan et al). 
While persulfate bleaching agents have low environmental impact, they have 
the disadvantage that their bleaching activity is slow and thus requires 
the presence of a bleaching accelerator or the use of an accelerator 
prebath, as widely practiced to process motion picture films. The most 
common bleaching accelerators are thiols that have offensive odors. 
Because hydrogen peroxide reacts and decomposes to form water, a peroxide 
based bleaching solution offers many environmental advantages over 
persulfate and ferric complex bleaching solutions. As a result, many 
publications describe peroxide bleaching solutions, including U.S. Pat. 
No. 4,277,556 (Koboshi et al), U.S. Pat. No. 4,301,236 (Idota et al), U.S. 
Pat. No. 4,454,224 (Brien et al), U.S. Pat. No. 4,717,649 (Hall et al), 
U.S. Pat. No. 5,550,009 (Haye et al), U.S. Pat. No. 5,541,041 (Haye), U.S. 
Pat. No. 5,641,615 (Haye et al), WO-A-92/01972 (published Feb. 6, 1992), 
WO-A-92/07300 (published Apr. 30, 1992) and EP 0 428 101A1 (published May 
22, 1991). These compositions may comprise various amounts of chloride 
ions and have a pH in the range of 5 to 11. 
Hydrogen peroxide bleaching compositions, however, often cause physical 
defects in the processed photographic elements, such as blistering (or 
vesiculation), and suffer long term stability problems at certain acidity 
levels. In addition, peroxide is ineffective in oxidizing developed silver 
to silver halide at acidic pH values, and thus it cannot be used to 
directly replace current high valent metal ligand bleaching solutions. 
There is a desire and need in the photographic industry to find solutions 
to all of these problems. Thus, there is a need to avoid the use of 
bleaching accelerators and high valent metal bleaching agents while 
providing an effective acidic bleaching environment. 
In copending and commonly assigned U.S. Ser. No. 08/947,072, filed on Oct. 
8, 1997, noted above, useful acidic periodate bleaching compositions and 
methods of bleaching are described. However, such methods include the use 
of an acidic prebath immediately before bleaching. 
The purpose of this acidic prebath is two-fold. Firstly, it serves as a 
wash solution to remove any residual color developing agent carried over 
by the processed element from the color developer solution. Secondly, it 
serves to lower the pH within the element layers to a level at which any 
incorporated dye forming color couplers are no longer reactive with 
oxidized color developing agent. Without the prebath before bleaching, the 
processed element would carry color developing agent into the bleaching 
solution, and this color developing agent would be oxidized by bleaching 
agent. Additionally, incorporated dye forming color couplers may still be 
reactive with oxidized color developing agent, forming additional dye. 
Since this dye formation would occur in a non-imagewise fashion, the newly 
formed dye would be seen as undesirable overall dye "stain" in the 
processed photographic element. 
Yet, there remains a need in the art to eliminate the use of the acidic 
prebath so as to reduce the number of steps to be followed and solutions 
to be prepared and maintained. Thus, prebath elimination would increase 
processing time and productivity in a processing facility. 
In order to process such photographic elements without the use of an acidic 
prebath, the bleaching solution must be sufficiently oxidizing to oxidize 
developed silver to a silver salt, but acidic enough to deactivate the 
reactive dye forming color couplers in the elements before they can react 
with color developing agent carried over from the color developer 
solution. With relatively weak oxidizing bleaching agents, such as 
chelated high valence metal ions (for example, the common ferric chelates 
of aminocarboxylic acids), bleaching compositions may be formulated over a 
wide range of acidity and bleaching agent concentration for silver 
oxidization without unwanted dye stain. These expectations can be 
characterized as the need to reduce residual silver in a processed element 
to below about 0.04 g/m.sup.2, and to minimize dye stain, or minimum 
density (Dmin) in unexposed areas. Acceptable Dmin would be that obtained 
from comparable processing of the same element using an acidic prebath 
prior to the use of a conventional chelated iron bleaching agent. 
When much stronger oxidants are used as bleaching agents, however, we 
discovered that there is less flexibility in formulating a bleaching 
composition that performs all of the desired functions without dye stain. 
For example, merely using the periodate bleaching compositions and methods 
described in our copending U.S. Ser. No. 08/947,072, noted above, in the 
absence of an acidic prebath, did not provide desired results. Bleaching 
was effective in most cases, but dye stain was unacceptably increased. 
Thus, there is a need to find a way to use a periodate bleaching 
composition in the absence of acidic prebath solutions. 
SUMMARY OF THE INVENTION 
The problems noted above are overcome with a method of processing 
comprising the steps of: 
A) color developing an imagewise exposed silver halide color photographic 
element, and 
B) without intervening processing steps, bleaching the element with the 
bleaching composition having a pH of less than 2, and comprising: 
a) periodate, or a source of periodate, at a concentration of from about 
0.01 to about 0.05 mol/l, 
b) chloride ions at a concentration of at least 0.01 mol/l, and 
c) at least one acid with a pKa less than 2, at a concentration greater 
than or equal to 0.05 mol/l. 
The periodate bleaching compositions useful in this invention can replace 
the peroxide or peracid solutions known in the art, and in some cases, can 
shorten the bleaching time. For example, bleaching of some silver chloride 
color photographic papers can be carried out in less than 30 seconds. 
Other elements also have shortened bleaching steps. In addition, the usual 
acidic prebath steps between color development and bleaching can be 
avoided with the careful formulation of pH and concentration of periodate 
bleaching agent in the bleaching composition. It functions both to stop 
color development as well as to rapidly bleach the developed photographic 
element. 
Thus, the bleaching compositions used in the practice of this invention 
satisfy the two essential criteria noted above when acidic prebath 
solutions are eliminated: effective bleaching so that residual silver is 
less than about 0.04 g/m.sup.2 of processed element, and minimal Dmin or 
dye stain in unexposed areas. 
Unlike persulfate bleaching compositions, the periodate compositions useful 
in this invention do not require a bleaching accelerator to be effective. 
In addition, the high valent metal bleaching agents that present 
environmental concerns are avoided. Unlike peroxide bleaching 
compositions, the periodate bleaching compositions easily convert 
developed silver to silver halide at very acidic pH values (for example at 
a pH below 2). No physical defects (such as blistering or vesiculation) 
are observed in the processed elements.

DETAILED DESCRIPTION OF THE INVENTION 
The method of this invention includes color developing a silver halide 
color photographic element using any of the conventional color developing 
solutions known in the art. Such solutions typically include one or more 
color developing agents, antioxidants (or preservatives), sequestrants, 
halides, buffers, and other addenda that would be known in the art. 
Particularly useful color developing agents include aminophenols and 
p-phenylenediamines, and particularly useful antioxidants include 
substituted and unsubstituted hydroxylamines, hydrazines, hydrazides, 
sulfites, a-amino acids, mono- and polysaccharides, and alcoholamines. By 
substituted hydroxylamines is meant, for example, those having one or more 
alkyl or aryl groups connected to the nitrogen atom. These alkyl or aryl 
groups can be further substituted with one or more groups such as sulfo, 
carboxy, carbamoyl, sulfamoyl, hydroxy, alkoxy, and other groups known in 
the art which provide solubilizing effects. Examples of such 
hydroxylamines are described, for example, in U.S. Pat. No. 4,876,174 
(Ishikawa et al), U.S. Pat. No. 4,892,804 (Vincent et al), U.S. Pat. No. 
5,178,992 (Yoshida et al), U.S. Pat. No. 5,354,646 (Kobayashi et al), U.S. 
Pat. No. 5,508,155 (Marrese et al), and WO US96/03016 (Eastman Kodak). 
Development can also be carried out using what is known in the art as a 
"developer/amplifier" solution, as described in U.S. Pat. No. 5,324,624 
(Twist). 
The amounts of the components of the color developing solution would be 
those considered conventional in the art. Further details of useful color 
developing solutions are provided in Research Disclosure, publication 
36544, pages 501-541 (September 1994). Research Disclosure is a 
publication of Kenneth Mason Publications Ltd., Dudley House, 12 North 
Street, Emsworth, Hampshire PO10 7DQ England (also available from Emsworth 
Design Inc., 121 West 19th Street, New York, N.Y. 10011). This reference 
will be referred to herein as "Research Disclosure". 
Following color development, without any intervening processing steps, such 
as acidic treatments or washes, the color photographic element is bleached 
using the periodate composition described herein. These compositions 
contain one or more suitable sources of periodate, including, but not 
limited to hydrogen, alkali and alkaline earth salts, or a compound which 
releases or generates periodate. Alkali metal periodates, such as sodium 
periodate, are preferred bleaching agents. 
Periodate exists in different forms in solution as a function of pH (see 
for example, Cotton and Wilkinson, Advanced Inorganic Chemistry, 2nd 
Edition, Interscience Publishers, New York, 1966, pp. 572-4), so that the 
form or forms of periodate that are the active bleaching agent(s) may vary 
as the bleaching composition pH varies. However, the most convenient 
sources of the active form(s) of the periodate bleaching agent for the 
preparation of bleaching compositions are the water-soluble salts of meta- 
and paraperiodic acids. 
The amount of periodate (or its precursor) is generally at least 0.01 
mol/l, preferably from about 0.01 to about 0.05 mol/l, and more preferably 
from about 0.01 to about 0.025 mol/l. 
The periodate bleaching compositions also include chloride ions as a 
rehalogenating agent. This rehalogenating agent can be supplied as part of 
a simple inorganic salt for example, sodium chloride, potassium chloride, 
ammonium chloride, lithium chloride, and others readily apparent to one 
skilled in the art. In addition, it can be supplied as an organic salt 
such as a tetraalkylammonium chloride. The preferred salts are potassium 
and sodium chlorides. 
The concentration of the chloride ions is generally from about 0.01 to 
about 1 mol/l, preferably from about 0.01 to 0.1 mol/l. 
The periodate compositions also include one or more acids, each having a 
pKa of less than 2, preferably less than 1.5, and more preferably less 
than 1. The total concentration of the acid(s) is greater than or equal to 
0.05 mol/l, preferably greater than or equal to 0.1 mol/l. 
The bleaching composition useful herein is highly acidic, having a pH less 
than 2, preferably less than 1.5, and more preferably, less than 1.25. The 
pH can be provided by adding at least one conventional strong acid, 
including, but not limited to, sulfuric acid, phosphoric acid and 
methanesulfonic acid. Sulfuric acid is preferred. 
The bleaching compositions are quite simple, having only the essential 
components described above. However, they may also include one or more 
distinct phosphonic acid or carboxylic acid sequestering agents, or 
corrosion inhibitors (such as nitrate ion) in conventional amounts. 
The periodate bleaching composition may be completely free of any purposely 
added complex of a high valent metal ion and any polycarboxylic acid, 
aminopolycarboxylic acid or phosphonic acid ligand. This does not mean 
that such complexes might not be carried over from the color developing 
solution into the bleaching bath, but if this occurs, the maximum 
concentration should be less than 1.times.10.sup.-4 mol/l, and preferably 
less than 1.times.10.sup.-4 mol/l, but clearly none of such complexes or 
the high valent metal ion to make such complexes, is purposely added to 
the bleaching compositions. Such carryover amounts are insufficient to 
perform the bleaching function. High valent metal ions are metal ions 
having a valence greater than +1, including iron(II), iron(III), 
copper(II), cobalt(II) and nickel(II). 
Fixing of the processed element can be accomplished using any suitable 
fixing solution containing one or more suitable fixing agents. 
Representative fixing agents are described in Research Disclosure, noted 
above. Preferred fixing agents include thioethers, thiocyanates and 
thiosulfates. The components of the fixing solutions are present in 
conventional amounts. 
The photographic elements processed using the present invention may be any 
suitable photographic color negative film, color reversal film, color 
paper, or motion picture films of all types. Each of these materials may 
be processed using a periodate bleaching composition in combination with 
the various conventional processing steps known in the art. The 
conditions, times and solutions used for such processing steps are well 
known or readily ascertained by a skilled worker in the art. 
The photographic elements processed according to this invention can have 
any suitable combination of silver halide emulsion layers that are known 
in the art. The present invention is particularly useful to process 
photographic color papers, especially those having one or more 
predominantly silver chloride emulsions, meaning an emulsion having at 
least 50 mol % silver chloride. The other emulsions in the color paper can 
be the same or different, but preferably, all of the emulsions in the 
papers are predominantly silver chloride emulsions. Thus, the red, green 
and blue color records each have at least one predominantly silver 
chloride emulsion. More preferably, each emulsion has at least 90 mol % 
silver chloride, and most preferably, each emulsion has at least 95 mol % 
silver chloride. The predominantly silver chloride emulsions contain 
substantially no silver iodide, meaning less than 1 mol % of silver 
iodide. Any remaining silver halide in such emulsions is silver bromide. 
The photographic emulsions used in these elements can have any suitable 
silver halide grain morphology including cubic, octahedral or tabular 
morphologies as described in numerous publications in the art, including 
Research Disclosure, noted above. Silver chloride emulsions can have 
tabular grains with {100} faces. 
The photographic elements processed in the practice of this invention can 
be single or multilayer color elements. Multilayer color elements, such as 
multilayer color papers, are particularly suitable, and typically contain 
dye image-forming units sensitive to each of the three primary regions of 
the visible spectrum. Each unit can be comprised of a single emulsion 
layer or multiple emulsion layers sensitive to a given region of the 
spectrum. The layers of the element can be arranged in any of the various 
orders known in the art. In an alternative format, the emulsions sensitive 
to each of the three primary regions of the spectrum can be disposed as a 
single segmented layer. The elements can also contain other conventional 
layers such as filter layers, interlayers, subbing layers, overcoats and 
other layers readily apparent to one skilled in the art. 
The multicolor photographic elements processed according to this invention 
can advantageously have one or more appropriate cyan, yellow and magenta 
dye forming couplers in one or more silver halide emulsion layers. Various 
classes of such coupler compounds are known, as described in Research 
Disclosure noted above. Particularly useful magenta dye forming couplers 
include both two- and four- equivalent azole and pyrazole (especially 
two-equivalent pyrazolotriazole) couplers. 
Considerably more details of the color photographic element structure and 
components are described in Research Disclosure, noted above. All types of 
emulsions can be used in the elements, including but not limited to, thin 
tabular grain emulsions, and either positive-working or negative-working 
emulsions, and the levels of silver coverage in the various types of 
elements can be any of those conventional in the industry. For example, 
the color papers processed using this invention have low total silver 
coverage, that is up to about 1 g/m.sup.2, and preferably up to about 0.75 
g/m.sup.2. 
The elements are typically exposed to suitable radiation to form a latent 
image and then processed as described above to form a visible dye image. 
The fixing step described above can be followed by one or more washing 
and/or stabilizing steps, then drying to provide the desired image. 
Processing according to the present invention can be carried out using 
conventional processing equipment, including what are known in the art as 
"low volume thin tank" processing systems having either rack and tank or 
automatic tray designs. Such processing methods and equipment are 
described, for example, in U.S. Pat. No. 5,436,118 (Carli et al) and 
publications noted therein. 
Bleaching according to the present invention is generally carried out for 
at least 30 seconds, and preferably at least 45 seconds. The maximum 
bleaching time will depend upon the type of element being processed. For 
example, high silver chloride color papers can be bleached in less than 
about 30 seconds. 
Bleaching temperatures are generally from about 20.degree. to about 
50.degree. C., and preferably from about 25.degree. to about 45.degree. C. 
Optimal bleaching temperatures can be readily determined for a given 
processed element with routine experimentation. 
The following examples are presented to illustrate the practice of this 
invention, and are not intended to be limiting in any way. Unless 
otherwise indicated, all percentages are by weight. 
Materials and Methods: 
Unless otherwise indicated, the photographic elements processed in the 
examples were imagewise exposed for 0.1 second on a 1B sensitometer 
(3000K) through a 0-3 step chart and HA-50 and NP-11 filters. The elements 
were processed using the various processing protocols at 35.degree. C. 
The residual silver for each of the 21 steps in the 0-3 chart was measured 
using conventional X-ray fluorescence XRF). The measured values 
(g/m.sup.2) are shown in the various tables. In those tables, "DF" 
represents a photographic element that has been developed and then fixed 
only. It gives the level of silver developed in the photographic process. 
This is the level of silver that needs to be bleached. "DBF" represents an 
element that has been developed, then bleached and fixed (full process). 
For a useful bleach, the silver levels in a DBF strip should be low, below 
about 0.040 g/m.sup.2. "DB" represents an element that has been developed 
and bleached only (no fix). It is desirable for a bleach to be 
silver-retentive, that is, that all of the developed silver oxidized by 
the bleach should remain in the element until the fixing step. A bleach is 
silver retentive to the degree that the silver levels in the DB strip are 
similar at all exposure levels and on the order of the highest silver 
levels in the DF strip. Strip "DBF-1" gives the residual silver in an 
element fully processed in conventional processes using a conventional 
chelated iron bleaching agent. "DB-1" shows the silver level in the same 
element after the bleaching step in the conventional processes. Strip 
"DBF-2" gives the residual silver in an element fully processed in the 
method of this invention using a periodate bleaching composition within 
the scope of this invention, and Strip "DB-2" shows the silver level in 
the same element after the bleaching step in the method of this invention. 
Strip "DBF-3" gives the residual silver in an element fully processed 
using the method protocol of this invention but with a hydrogen peroxide, 
sodium persulfate or periodate bleaching composition outside of this 
invention, and "DB-3" shows the silver level in the same element after the 
bleaching step. 
Minimum Status A reflection densities (Dmins) were measured on the fully 
processed film strips. 
Processing solutions used in the examples include: 
______________________________________ 
Color Developer 
Water 700.0 ml 
Triethanolamine 12.41 g 
PHORWITE REU 2.30 g 
Lithium polystyrene sulfonate (30% solution) 
0.30 g 
N,N-diethylhydroxylamine (85% solution) 
5.40 g 
Lithium sulfate 2.70 g 
KODAK Color Developing Agent CD-3 
5.00 g 
1 Hydroxyethyl-1,1-diphosphonic acid 
1.16 g 
(60% solution) 
Potassium carbonate, anhydrous 
21.16 g 
Potassium bicarbonate 2.79 g 
Potassium bromide 7.00 mg 
Water to make 1.00 liter 
pH = 10.04 (at 27.degree. C.) 
Color Paper Bleaching Solution 
1,3-Propanediaminetetraacetic acid (PDTA) 
15.40 g 
Ferric nitrate, 9-hydrate 
18.30 g 
Glacial acetic acid 6.00 ml 
1,3-Diamino-2-propanoltetraacetic acid 
0.50 g 
Potassium bromide 23.90 g 
Water to make 1.00 liter 
pH = 4.75 (at 25.degree. C.) 
Fixing Solution 
Sodium thiosulfate 42.60 g 
Sodium sulfite 18.60 g 
Glacial acetic acid 10.00 ml 
Disodium ethylenediaminetetraacetate 
1.00 g 
Water to make 1.00 liter 
pH = 6.50 (at 25.degree. C.) 
______________________________________ 
EXAMPLE 1 
This example shows that a periodate bleaching composition can be used to 
replace three conventional processing solutions (acidic stop bath, water 
wash, and chelated iron bleaching solution) in the conventional "Separate 
Bleach and Fixer Option" for Process RA-4 used to process color 
photographic papers. 
Conventional FUJICOLOR SUPER FA5 Color Paper was exposed and processed 
according to the following processing protocol. 
______________________________________ 
Time (sec) 
Solution DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
Color Developer 45 45 45 45 45 
Acidic Prebath 30 30 30 -- -- 
Water wash 30 30 30 -- -- 
Color Paper Bleaching Solution 
-- 60 60 -- -- 
Bleach A -- -- -- 110 110 
Water wash 120 60 60 60 60 
Fixing Solution 60 60 -- 60 -- 
Water wash 90 90 150 90 150 
______________________________________ 
Acidic Prebath 
Glacial acetic acid 9.0 ml 
Water to 1 liter 
Bleaching Composition A 
Sodium periodate 2.14 grams 
Sodium chloride 0.88 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 0.79 
______________________________________ 
The residual silver values are shown below in TABLE I, and the Dmin values 
are shown below in TABLE II. The data in TABLE I show that the method of 
this invention provides comparable silver retentive bleaching compared to 
the conventional method in which acidic prebath and washing steps were 
used. A comparison of the Dmin values shows that there was no increase in 
red, green or blue Dmin with the method of this invention. 
TABLE I 
______________________________________ 
Control Bleach A 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.501 0.000 0.538 0.000 0.539 
0.508 0.000 0.540 0.005 0.548 
0.526 0.000 0.537 0.005 0.533 
0.485 0.000 0.544 0.011 0.535 
0.481 0.004 0.543 0.005 0.535 
0.490 0.000 0.542 0.004 0.552 
0.455 0.000 0.524 0.010 0.550 
0.443 0.003 0.540 0.000 0.537 
0.423 0.000 0.533 0.001 0.538 
0.330 0.000 0.531 0.000 0.537 
0.219 0.002 0.533 0.000 0.536 
0.145 0.001 0.540 0.000 0.543 
0.073 0.000 0.544 0.003 0.535 
0.031 0.000 0.535 0.000 0.540 
0.008 0.009 0.526 0.006 0.550 
0.000 0.000 0.533 0.000 0.542 
0.000 0.000 0.550 0.000 0.543 
0.002 0.000 0.542 0.004 0.543 
0.002 0.005 0.523 0.003 0.541 
0.000 0.000 0.552 0.000 0.541 
0.002 0.000 0.538 0.000 0.538 
______________________________________ 
TABLE II 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.119 0.119 0.136 
(control) 
DBF-2 0.119 0.118 0.137 
(invention) 
______________________________________ 
Comparative Example 1 
This example shows that if hydrogen peroxide or sodium persulfate is 
substituted (on an equimolar basis) for periodate as the bleaching agent 
in Bleaching Composition A and the method of Example 1 is repeated, 
bleaching of developed silver is not achieved. Thus, periodate is shown to 
be effective as a bleaching agent in the processing method of this 
invention while hydrogen peroxide and sodium persulfate, both common 
bleaching agents, are not. 
The process of Example 1 was repeated, using either Bleaching Composition B 
or C. 
______________________________________ 
Bleaching Composition B 
Hydrogen peroxide (30 wt % in water) 
1.13 grams 
Sodium chloride 0.88 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 0.72 
Bleaching Composition C 
Sodium persulfate 2.38 grams 
Sodium chloride 0.88 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 0.72 
______________________________________ 
The residual silver values are shown below in TABLE III. 
TABLE III 
______________________________________ 
Bleach B Bleach C 
DF DBF-3 DB-3 DBF-3 DB-3 
______________________________________ 
0.524 0.500 0.547 0.462 0.534 
0.508 0.490 0.545 0.467 0.537 
0.496 0.482 0.549 0.449 0.535 
0.500 0.470 0.531 0.457 0.531 
0.485 0.457 0.540 0.450 0.538 
0.487 0.452 0.525 0.446 0.539 
0.482 0.432 0.529 0.419 0.536 
0.443 0.408 0.539 0.400 0.540 
0.412 0.392 0.531 0.373 0.545 
0.316 0.301 0.536 0.292 0.539 
0.226 0.218 0.540 0.205 0.531 
0.139 0.123 0.539 0.126 0.527 
0.067 0.065 0.542 0.060 0.541 
0.027 0.028 0.530 0.022 0.543 
0.016 0.014 0.542 0.000 0.544 
0.000 0.000 0.523 0.000 0.542 
0.002 0.001 0.523 0.001 0.539 
0.003 0.000 0.544 0.000 0.547 
0.012 0.005 0.525 0.005 0.535 
0.000 0.009 0.537 0.000 0.529 
0.000 0.001 0.531 0.000 0.525 
______________________________________ 
EXAMPLE 2 
Raid Processing 
This example demonstrates rapid bleaching in a shortened process of this 
invention. Samples of conventional FUJICOLOR SUPER FA5 Color Paper were 
exposed and processed as in Example 1 except that Bleach A was replaced 
with Bleaching Composition D and the time for bleaching was reduced to 30 
seconds. Thus, the 120 seconds total application time of the acidic 
prebath, the water wash and the Color Paper Bleaching Solution in the 
control process was replaced by the 30 seconds bleaching time in the 
invention process. The residual silver values are shown in Table IV. Table 
V shows that the Dmin values for the invention were comparable to the 
conventional process. 
______________________________________ 
Bleaching Composition D 
______________________________________ 
Sodium periodate 3.21 grams 
Sodium chloride 0.88 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 0.76 
______________________________________ 
TABLE IV 
______________________________________ 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.499 0.010 0.540 0.010 0.530 
0.515 0.003 0.533 0.014 0.541 
0.515 0.010 0.531 0.010 0.531 
0.508 0.009 0.535 0.014 0.549 
0.487 0.002 0.541 0.003 0.542 
0.478 0.003 0.527 0.012 0.570 
0.471 0.000 0.523 0.019 0.536 
0.452 0.000 0.539 0.014 0.549 
0.400 0.008 0.524 0.003 0.533 
0.343 0.005 0.545 0.009 0.534 
0.243 0.001 0.543 0.000 0.540 
0.142 0.000 0.535 0.011 0.547 
0.082 0.000 0.548 0.011 0.543 
0.031 0.008 0.533 0.000 0.527 
0.011 0.012 0.529 0.000 0.536 
0.002 0.004 0.526 0.000 0.548 
0.011 0.005 0.531 0.002 0.539 
0.010 0.000 0.535 0.002 0.530 
0.003 0.009 0.534 0.001 0.529 
0.014 0.000 0.536 0.000 0.526 
0.002 0.002 0.537 0.004 0.528 
______________________________________ 
TABLE V 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.118 0.117 0.136 
(control) 
DBF-2 0.122 0.122 0.141 
(invention) 
______________________________________ 
EXAMPLE 3 
This example demonstrates bleaching of commercially available KONICACOLOR 
QA TYPE A6E Color Paper using the present invention and 10 comparing the 
invention to processing using the "Separate Bleach and Fixer Option" for 
conventional Process RA-4. Samples of the color paper were exposed and 
processed as in Example 1. The residual silver values are shown below in 
TABLE VI. TABLE VII shows that the Dmin values for the invention were 
comparable to the conventional process. 
TABLE VI 
______________________________________ 
Control Bleach A 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.470 0.000 0.499 0.001 0.498 
0.472 0.000 0.497 0.011 0.499 
0.476 0.002 0.493 0.000 0.511 
0.467 0.000 0.502 0.014 0.501 
0.469 0.005 0.505 0.000 0.494 
0.462 0.000 0.493 0.000 0.498 
0.444 0.000 0.499 0.002 0.492 
0.431 0.000 0.494 0.006 0.501 
0.365 0.000 0.506 0.000 0.497 
0.272 0.000 0.497 0.000 0.500 
0.193 0.000 0.499 0.000 0.498 
0.086 0.000 0.502 0.000 0.493 
0.042 0.000 0.503 0.000 0.505 
0.012 0.000 0.499 0.000 0.495 
0.000 0.000 0.514 0.000 0.495 
0.000 0.000 0.500 0.000 0.502 
0.001 0.002 0.501 0.000 0.495 
0.000 0.000 0.497 0.002 0.496 
0.003 0.000 0.477 0.000 0.494 
0.000 0.000 0.494 0.000 0.508 
0.000 0.000 0.498 0.001 0.521 
______________________________________ 
TABLE VII 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.094 0.087 0.099 
(control) 
DBF-2 0.096 0.093 0.109 
(invention) 
______________________________________ 
EXAMPLE 4 
This example demonstrates bleaching of commercially available AGFACOLOR 
TYPE 10 Color Paper using the present invention and comparing the 
invention to processing using the "Separate Bleach and Fixer Option" for 
conventional Process RA-4. Samples of the color paper were exposed and 
processed as in Example 1. The residual silver values are shown in Table 
VIII. Table IX shows that the Dmin values obtained using the invention 
were comparable to those measured when the control bleach (of Example 1) 
was used. 
TABLE VIII 
______________________________________ 
Control Bleach A 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.640 0.008 0.656 0.029 0.653 
0.613 0.000 0.653 0.002 0.669 
0.625 0.006 0.662 0.028 0.653 
0.636 0.001 0.651 0.022 0.657 
0.608 0.000 0.652 0.029 0.673 
0.602 0.008 0.650 0.023 0.662 
0.568 0.004 0.651 0.026 0.644 
0.514 0.009 0.658 0.016 0.650 
0.431 0.000 0.651 0.014 0.638 
0.318 0.006 0.656 0.011 0.651 
0.211 0.005 0.646 0.000 0.671 
0.108 0.006 0.637 0.004 0.656 
0.059 0.001 0.658 0.013 0.661 
0.027 0.009 0.643 0.000 0.638 
0.011 0.000 0.656 0.000 0.667 
0.004 0.002 0.656 0.005 0.658 
0.002 0.012 0.652 0.014 0.670 
0.003 0.000 0.654 0.000 0.664 
0.003 0.004 0.644 0.006 0.648 
0.000 0.002 0.637 0.010 0.671 
0.003 0.002 0.638 0.005 0.653 
______________________________________ 
TABLE IX 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.114 0.107 0.117 
(control) 
DBF-2 0.110 0.112 0.123 
(invention) 
______________________________________ 
EXAMPLE 5 
This example demonstrates bleaching of KODAK EDGE 5 Color Paper using the 
present invention and comparing it to the "Separate Bleach and Fixer 
Option" for conventional Process RA-4. Samples of the color paper were 
exposed and processed as in Example 1. The residual silver values are 
shown below in TABLE X. TABLE XI shows the Dmin values obtained using the 
present invention to be comparable to those using the control process (of 
Example 1). 
TABLE X 
______________________________________ 
Control Bleach A 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.614 0.000 0.619 0.005 0.635 
0.581 0.000 0.618 0.015 0.634 
0.577 0.000 0.638 0.012 0.624 
0.582 0.011 0.640 0.014 0.625 
0.569 0.011 0.633 0.008 0.641 
0.553 0.002 0.651 0.011 0.637 
0.525 0.000 0.635 0.011 0.635 
0.496 0.022 0.616 0.014 0.626 
0.429 0.003 0.635 0.005 0.630 
0.337 0.005 0.630 0.000 0.634 
0.218 0.014 0.618 0.000 0.615 
0.118 0.004 0.641 0.008 0.637 
0.046 0.002 0.653 0.004 0.615 
0.023 0.003 0.637 0.001 0.624 
0.018 0.000 0.624 0.008 0.613 
0.000 0.000 0.638 0.000 0.732 
0.003 0.002 0.627 0.003 0.621 
0.012 0.005 0.665 0.000 0.623 
0.013 0.000 0.624 0.000 0.635 
0.005 0.000 0.620 0.005 0.628 
0.000 0.000 0.648 0.000 0.624 
______________________________________ 
TABLE XI 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.109 0.096 0.113 
(control) 
DBF-2 0.105 0.104 0.114 
(invention) 
______________________________________ 
EXAMPLE 6 
This example demonstrates bleaching of commercially available KODAK EDGE 7 
Color Paper using the present invention and comparing the invention to 
processing using the "Separate Bleach and Fixer Option" for conventional 
Process RA-4. Samples of the color paper were exposed and processed as in 
Example 1. The residual silver values are shown in TABLE XII. TABLE XIII 
shows that the Dmin values obtained using the invention were comparable to 
those measured when the control bleach (of Example 1) was used. 
TABLE XII 
______________________________________ 
Control Bleach A 
DF DBF-1 DB-1 DBF-2 DB-2 
______________________________________ 
0.389 0.011 0.406 0.017 0.402 
0.405 0.001 0.424 0.015 0.421 
0.408 0.004 0.396 0.016 0.412 
0.411 0.006 0.414 0.014 0.423 
0.397 0.000 0.412 0.012 0.410 
0.396 0.000 0.431 0.017 0.421 
0.374 0.001 0.411 0.012 0.415 
0.360 0.001 0.428 0.008 0.429 
0.322 0.011 0.419 0.008 0.421 
0.261 0.000 0.412 0.006 0.403 
0.171 0.000 0.419 0.000 0.431 
0.089 0.002 0.412 0.000 0.428 
0.036 0.001 0.414 0.001 0.407 
0.019 0.002 0.417 0.000 0.423 
0.006 0.003 0.424 0.000 0.424 
0.000 0.000 0.427 0.000 0.415 
0.001 0.006 0.416 0.005 0.423 
0.005 0.000 0.415 0.002 0.435 
0.000 0.003 0.416 0.000 0.420 
0.005 0.002 0.417 0.004 0.425 
0.010 0.004 0.393 0.011 0.417 
______________________________________ 
TABLE XIII 
______________________________________ 
Dmin 
R G B 
______________________________________ 
DBF-1 0.093 0.084 0.073 
(control) 
DBF-2 0.095 0.089 0.076 
(invention) 
______________________________________ 
EXAMPLE 7 
This example demonstrates that periodate bleaches with higher acidity 
levels are preferable in the practice of this invention because the 
minimum density levels are controlled better. In this example, acidity 
levels were varied by changing the concentration of a common buffering 
acid in three otherwise identical periodate bleaching compositions. 
Example 1 was repeated using Bleaching Compositions E, F and G and the 
bleach time was 60 seconds. The method using Composition E is outside the 
present invention because the acid concentration is too low. 
______________________________________ 
Bleaching Composition E 
Sodium periodate 2.14 grams 
Sodium chloride 2.93 grams 
Sulfuric acid (0.045 molar in water) to 
1 liter 
pH = 1.28 
Bleaching Composition F 
Sodium periodate 2.14 grams 
Sodium chloride 2.93 grams 
Sulfuric acid (0.090 molar in water) to 
1 liter 
pH = 1.08 
Bleaching Composition G 
Sodium periodate 2.14 grams 
Sodium chloride 2.93 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 1.08 
______________________________________ 
The residual silver values are shown below in Table XIV. A comparison of 
the minimum densities with respect to the control is shown in Table XV. 
The results in Table XIV show that the three bleaching compositions E, F 
and G work equally well as silver retentive bleaching solutions. The 
results in Table XV show that the minimum density in strips fully 
processed in the current process relative to the minimum density in strips 
processed using the control bleach (like Example 1) decreases as the acid 
level is increased (that is, as pH is decreased). 
TABLE XIV 
______________________________________ 
Bleach E Bleach F Bleach G 
DF DBF-3 DB-3 DBF-2 DB-2 DB-2 DB-2 
______________________________________ 
0.538 0.000 0.561 0.003 0.581 
0.033 0.557 
0.534 0.000 0.562 0.000 0.581 
0.030 0.566 
0.510 0.000 0.565 0.011 0.577 
0.033 0.564 
0.524 0.001 0.564 0.010 0.550 
0.029 0.584 
0.507 0.000 0.568 0.000 0.549 
0.024 0.564 
0.509 0.009 0.570 0.000 0.566 
0.033 0.556 
0.481 0.000 0.552 0.000 0.567 
0.036 0.567 
0.443 0.001 0.585 0.005 0.566 
0.012 0.574 
0.395 0.006 0.547 0.014 0.564 
0.024 0.569 
0.329 0.000 0.566 0.006 0.574 
0.018 0.577 
0.243 0.000 0.563 0.000 0.573 
0.000 0.576 
0.146 0.000 0.573 0.012 0.559 
0.000 0.572 
0.074 0.000 0.557 0.000 0.569 
0.000 0.561 
0.026 0.000 0.576 0.000 0.571 
0.012 0.567 
0.014 0.000 0.551 0.009 0.580 
0.000 0.587 
0.009 0.000 0.554 0.000 0.567 
0.000 0.574 
0.002 0.000 0.591 0.000 0.574 
0.000 0.536 
0.000 0.000 0.563 0.005 0.580 
0.000 0.566 
0.000 0.000 0.566 0.001 0.580 
0.000 0.561 
0.002 0.000 0.551 0.002 0.582 
0.000 0.581 
0.011 0.000 0.566 0.000 0.556 
0.000 0.562 
______________________________________ 
TABLE XV 
______________________________________ 
Dmin 
Bleach sample R G B 
______________________________________ 
Color Paper Bleach 
control 0.106 0.104 
0.120 
E DBF-3 0.159 0.130 
0.143 
Color Paper Bleach 
control 0.113 0.112 
0.127 
F DBF-2 0.122 0.118 
0.134 
(invention) 
Color Paper Bleach 
control 0.105 0.104 
0.120 
G DBF-2 0.110 0.107 
0.123 
(invention) 
______________________________________ 
EXAMPLE 8 
This example demonstrates that periodate bleaching compositions having 
higher acidity levels (lower pH) are preferable in the bleaching method of 
the present invention because such solutions control the minimum density 
levels in strips fully processed according to the present invention. In 
this example, the pH of bleaching compositions having identical periodate 
and chloride concentrations were varied by replacing sulfuric acid with 
acids of lower acid strength. 
Example 1 was repeated except that Bleaching Compositions H and I were used 
and the bleach time was 60 seconds. The method using Composition H is 
outside the present invention because the Composition H pH is too high. 
The use of Composition I is within the present invention. 
______________________________________ 
Bleaching Composition H 
Sodium periodate 2.14 grams 
Sodium chloride 2.93 grams 
Glacial acetic acid 15.0 grams 
Water to 1 liter 
pH = 2.56 
Bleaching Composition I 
Sodium periodate 2.14 grams 
Sodium chloride 2.93 grams 
Phosphoric acid (85 wt % in water) 
23.0 grams 
Water to 1 liter 
pH = 1.24 
______________________________________ 
The residual silver data are shown below in TABLE XVI. A comparison of the 
minimum densities with respect to the control (of Example 1) is shown in 
TABLE XVII. The results in Table XVI show that both Bleaching Compositions 
H and I are effective at desilvering the developed color paper, but the 
data in Table XVII show that bleaching at the lower pH is needed to reduce 
Dmin to an acceptable level. 
TABLE XVI 
______________________________________ 
Bleach H Bleach I 
DF DBF-3 DB-3 DBF-2 DB-2 
______________________________________ 
0.521 0.000 0.577 0.005 0.581 
0.522 0.000 0.590 0.002 0.561 
0.502 0.011 0.588 0.014 0.580 
0.503 0.000 0.572 0.022 0.583 
0.485 0.005 0.581 0.013 0.568 
0.472 0.000 0.570 0.017 0.579 
0.464 0.010 0.569 0.016 0.590 
0.424 0.000 0.582 0.008 0.580 
0.384 0.011 0.586 0.018 0.578 
0.313 0.014 0.566 0.015 0.590 
0.228 0.002 0.590 0.000 0.573 
0.141 0.000 0.574 0.004 0.570 
0.083 0.000 0.585 0.012 0.555 
0.034 0.003 0.581 0.002 0.592 
0.012 0.000 0.585 0.006 0.568 
0.015 0.000 0.574 0.011 0.578 
0.012 0.004 0.555 0.003 0.579 
0.011 0.011 0.563 0.009 0.572 
0.004 0.003 0.583 0.012 0.590 
0.002 0.000 0.549 0.008 0.586 
0.005 0.000 0.561 0.009 0.567 
______________________________________ 
TABLE XVII 
______________________________________ 
Dmin 
Bleach Sample R G B 
______________________________________ 
Color Paper Bleach 
control 0.117 0.117 
0.129 
H DBF-3 0.144 0.175 
0.204 
Color Paper Bleach 
control 0.113 0.112 
0.125 
I DBF-2 0.120 0.121 
0.145 
(invention) 
______________________________________ 
EXAMPLE 9 
This example demonstrates that for periodate bleaching compositions useful 
in the present invention, lower periodate concentrations are preferred at 
the same acidity level (pH). The lower periodate concentrations generate 
less undesirable Dmin. 
Example 1 was repeated using Bleaching Compositions J, K and L, and the 
bleach time was 60 seconds. Bleach compositions K and L are outside the 
scope of the present invention because the periodate concentrations are 
above 0.05 mol/l. 
______________________________________ 
Bleaching Composition J 
Sodium periodate 10.7 grams 
Sodium chloride 5.84 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 1.02 
Bleaching Composition K 
Sodium periodate 16.0 grams 
Sodium chloride 5.84 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 1.06 
Bleaching Composition L 
Sodium periodate 21.4 grams 
Sodium chloride 5.84 grams 
Sulfuric acid (0.18 molar in water) to 
1 liter 
pH = 0.75 
______________________________________ 
TABLES XVIII and XIX show the residual silver and Dmin data, respectively. 
The results show that all three Bleaching Compositions J, K, and L were 
effective at desilvering the developed color paper, and the data in Table 
XIX show that the higher the periodate concentration, the higher the 
increase in Dmin relative to strips processed in the control process (of 
Example 1). 
TABLE XVIII 
______________________________________ 
Bleach J Bleach K Bleach L 
DF DBF-2 DB-2 DBF-3 DB-3 DBF-3 DB-3 
______________________________________ 
0.536 0.000 0.565 0.000 0.561 
0.003 0.579 
0.537 0.017 0.577 0.000 0.580 
0.000 0.574 
0.523 0.000 0.564 0.000 0.583 
0.000 0.588 
0.526 0.000 0.579 0.000 0.570 
0.000 0.573 
0.506 0.000 0.563 0.000 0.570 
0.004 0.574 
0.512 0.000 0.592 0.000 0.569 
0.015 0.570 
0.486 0.004 0.572 0.001 0.551 
0.000 0.572 
0.446 0.002 0.579 0.000 0.580 
0.001 0.564 
0.401 0.000 0.551 0.006 0.567 
0.004 0.570 
0.327 0.000 0.554 0.015 0.583 
0.000 0.571 
0.241 0.000 0.581 0.000 0.568 
0.000 0.577 
0.150 0.000 0.578 0.000 0.554 
0.002 0.557 
0.075 0.003 0.567 0.002 0.572 
0.004 0.559 
0.026 0.001 0.578 0.006 0.578 
0.005 0.568 
0.015 0.000 0.564 0.000 0.562 
0.000 0.569 
0.008 0.004 0.568 0.013 0.586 
0.000 0.577 
0.001 0.009 0.553 0.000 0.570 
0.000 0.580 
0.002 0.003 0.570 0.000 0.574 
0.000 0.555 
0.002 0.000 0.585 0.000 0.572 
0.000 0.569 
0.001 0.000 0.576 0.011 0.580 
0.000 0.573 
0.006 0.000 0.570 0.000 0.567 
0.003 0.583 
______________________________________ 
TABLE XIX 
______________________________________ 
Dmin 
Bleach sample R G B 
______________________________________ 
Color Paper Bleach 
control 0.116 0.114 
0.131 
J DBF-2 0.132 0.129 
0.145 
(invention) 
Color Paper Bleach 
control 0.114 0.113 
0.127 
K DBF-3 0.177 0.162 
0.169 
Color Paper Bleach 
control 0.112 0.111 
0.126 
L DBF-3 0.234 0.211 
0.201 
______________________________________ 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.