The Effects of Sludge on the Image Quality of a Particular Film-Monobath Combination

Rochester Institute of Technology

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5-1-1966

The Effects of Sludge on the Image Quality of a

Particular Film-Monobath Combination

Alfred DiLascia

Ronald Hubbard

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Recommended Citation

THE EFFECTS OF SLUDGE ON THE IMAGE

QUALITY OF A PARTICULAR

FILM-MONOBATH COMBINATION

by

Alfred T. DiLascia

Ronald Hubbard

May,

1966

G

ZoCLpT /ol.

ABSTRACT

Sludge is considered

_by

_many to be a factor

_limiting

the usefulness of

monobaths. A particular film-monobath combination was tested for the effects

of sludge on _{sensltometry, granularity,} and acutance. It was found that the

presence of sludge did not alter the sensitometric characteristics;

_however,

through solution _usage, the acutance and _granularity decreased. Removal of the

the sludge

_by

filtration

_during

usage resulted in improved image _quality over

The monobath type system has the characteristics of combined

_develop

ment and fixation carried out in a single solution. In general, a monobath

solution contains the normal

_developing

_agents, a preservative, a

_fairly

strong

base,

the

_fixing

agent (silver halide _solvent), and an antifoggant.

It is _necessary to manipulate these components in order to achieve a balance,

among resulting effects. The addition of the silver halide solvent often

reduces the _activity of the

_developing

agents. In order to speed _up the

development _{reaction, NaOH may be} added to raise the pH.

_{NaOH, however,}

2

causes _softening and _swelling of the emulsion. Thus it can be seen that

a monobath is

_basically

a compromise in components designed to optimize

the desired results and mininize the unwanted effects. For _example, to com

bat the loss in _activity of the

_developing

_agents, a phenidone-hydroquinone

combination is often used in place of _metol-HQ, which results in a marked

in-3

crease in _{speed, contrast,} and maximum density. Some disadvantages of NaOH

(swelling

of _emulsion, dangerous

_handling,

and _{susceptability} of solution to

to oxidation) can be lessened

_by

a substitution of

_NaCO^

without

_losing

devel-E J 4

oper _activity excessively.

The use of hypo as a

_fixing

agent limits the minimum time for complete

development and fixing. Substitution

offNHAS^C^

leads to shorter processing

^ ₆

times and finer _grain, but decomposes at high pH and yields ammonia. KSCN

produces short clearing times and appears to act as an accelerator of devel

opment. Used in conjunction with

_hypo,

rates of development and

_fixing

can

, 8 be balanced.

Some of the advantages of such a system are

_fairly

obvious. For _example,

the high speed and _simplicity of _processing attainable with monobaths is

2-temperature and agitation effects. A disadvantage

_frequently

mentioned in

the literature is the sludge problem. The objection here is the presence

of a sludge-like precipitate. It has been reported that this precipitate is

formed

_by

the reduction of the argento-thiosulfate (or thiocyanate) complex

in the solution. it is felt

_by

some that the presence of this sludge limits

12

the _practicality of monobath type solutions. it is not made clear _exactly

why the sludge is considered a

_limiting

_factor,

but some possible consequences

of the sludge are _readily apparent. Such factors as adhesion to film surface

and adverse effects on sensitometric and image _{quality may} be possible ob

jections.

The development mechanism in solutions _containing large amounts of

silver-halide solvents is believed to be

_basically

different from that in conventional

13

developers. The belief is that there is a competition between two types of

development reactions: solution-physical development vs. chemical development.

(For a discussion of these terms see James and

_Higgens,

Fundamentals of

Photographic Theory). In _general, solution-physical development results in

a higher photometric equivalent than chemical development.

The reason for this change in covering power

_(inversely

related to photo

metric equivalent) may be attributed to the fact that _{solution-physically}

developed silver _{may merely fill} in the porous structure of the _chemically

14 developed grain without _{significantly}

_increasing

the projected area. At

higher densities the influence on grain structure seems to be _{predominantly}

_by

chemical

_development,

whereas at low

_densities,

solution-physical development

15 plays the major role.

There is some difference in opinion in the literature on the effects of

film,

and _processing conditions. For _example, with a fast film it has been reported

_by

Barnes et

al1

that both acutance and _granularity improve with the use of a solvent type

_developer,

whereas Altman and Henn report a decrease

in acutance and _{granularity using a different solvent} type developer. If this work can be assumed to be _valid, there is tha _possiblity of some differences

in the exact mechanisms _operating in these cases. These _{uncertainties,}

_however,

are not considered a

_limiting

factor. On the other

_hand,

the effects of sludge

is a question which should be more

_thoroughly

investigated.

It is the purpose of this project to explore the effects of monobath sludge on image _quality for the film-developer combination mentioned below. The

response variables used for this evaluation are RMS _granularity and acutance.

Experimental Procedure:

18 The monobath chosen for this investigation is of a type _recently formulated.

It appears to have a high potential of rapid _processing applications because

[

of short _processing time. The basic formulation uses phenidone-hydroquinone as the

_developing

agents and thiosulfats-thiocyanate as the silver-halide sol

vent. (See p.4 of the Appendix for formulation). The film selected was East man Kodak 2494 RAR (Rapid Access Recording). The reason for this choice was the

film's high speed and hardened emulsion. The hardened emulsion was desired because of its _ability to withstand the _softening and reticulation that accom panies KSCN. The film's potential use in high temperature _processing was al so a factor.

Sensitometric wedges were exposed _using the Kodak Model 101 Sensitometer.

roll of film. Twenty-20 exposure _35mm rolls were exposed identically.

The _processing procedure was as follows:

1. Volume: Two-16 oz. containers of monobath (formulation in

Appendix)

were taken from the same 5gallon solution _{for processing} the treatment com

binations described below.

2. Conditions: 5 minute development at 68F. with constant agitation

(constant circular motion of roll film tank reel).

3. Finishing: vigorous 5 minute wash to remove _any sludge _adhering to

film surface, 30 second

_Photo-Flo,

and room temperature drying.

4. Treatment combinations: 10 runs (rolls of

_film)

were processed in

each of the above mentioned 16 oz. _solutions, corresponding runs

_being

used for

comparison. One solution was allowed to accumulate sludge throughout all runs.*

The other solution was filtered twice after each run with a Buchner funnel

apparatus. Whatman #42 fine analytical filter paper was used to remove the

sludge. Filtration removed all visible evidence of sludge in. all cases.

Sensitometric step wedges from the

_1st,

_6th,

and 10th runs were read on

the Macbeth TD 100 and plotted as

_density

vs. relative

_log

exposure. Granu

larity

patches from the 1st and 9th runs

_(0=1.0)

were scanned with the GAF

Model 4 Automatic

Recording

Microdensitometer used in conjuction with the

19

GAF Model 83

_Granularity

Integrator. The effective aperture used was a

16.4 u diameter circle.

_Thirty

icans were made on each patch. Knife-edge

traces from the 1st and 9th runs were scanned with the same model microden

sitometer. Seven non-overlapping scans were made of each edge. A 1 X 60 u

effective slit was used.

Silver mass/area analyses _using the Norelco

_X-ray

floresence technique

were run _using samples from the 1st and 9th runs at three

_density

_levels.

-5-The

_density

levels used were:

_D=1.0,

_1.3,

1.6.

Results:

The _sensitometry as shown on pages 7 and 8 were _visually compared and

showed no significant change throughout the series of _runs, and no change

between the filtered and sludged solutions. On this

_basis,

valid image eval

uation comparisons can be made.

The meter readings from the _{30 granularity} scans of each treatment under

analysis were averaged and the standard deviation of the readings was calculated

for each case. The means were tested _{statistically using} the Students "t"

distribution at ^=.005. i.t was found that there was a significant difference

between all three values. The RMS values are related

_linearly

to the meter

readings taken from the

_Granularity

_Integrator,

thus _validating this technique.*

(See page 10 for RMS values.)

The knife-edge analysis was performed

_by

_{superimposing} 7 scans of different

parts of the stirae edge and

_drawing

tEie smoothed visual average for each case.**

This technique produced four curves: one pair of 1st run (fresh solution)

replicates, one 9th run _sludged, and one 9th run filtered. (See page 9 for

smoothed curves). The acutance was calculated for each of these curves as

follows:

_2 _2

Acutance = _G

; where G = _{average of}

gradients-squared, and

20

iE;D=the

_density

difference. (For calculated _values, see page 10). These

values were _{statistically} tested _using trie stanaard deviation of the replicates

as an external estimate of error in the equation

_Af-As

=

t, for use with the

Se

Students "t"

distribution;

where _A~=acutance of 9th run

_filtered,

*Note: GAF calibration is linear.

6-Ag

=

acutance of 9th run _sludged, and

_Se

is the standard deviation mentioned

above. It was found that there was a significant difference between the 9th

run filtered and 9th run sludged with y =

.05. The same test was used to

show a significant difference between the acutance of the 1st run fresh and

the 9th run used solutions.

The silver analysis yielded relative figures

_indicating

Eaat the silver

mass/area (related

_directly

to photometric _equivalent) increased between the

1st and 9th _runs, and was higher in the filtered solucion than in the sludged

solution for equal densities. The increase in the silver mass/area appeared

to be greater at the lower

_density

levels than at the higher level where there

was little change.

The physical presence of the sludge caused no problems in _adhering to the

film or _{processing equipment;} thorough _washing with water removed the sludge.

Conclusions:

With the particular fiI..--monobath

investigated,

it was found that the pres

ence of sludge did not _{significantly} alter the sensitometric _{characteristics;}

however,

through solution _usage, the acutance and _granularity decreased signi

ficantly. Removal of the sludge

_by

filtration

_during

usage resulted in signi

ficantly

improved image _quality over the comparison solution in which sludge

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11-Discussion:

It would appear useful to attempt an explanation of the mechanism

involved which produced the _previously mentioned image _quality and _covering

power changes. A possible explanation of these results would be an increase

in the solution-physical type of development as the solution is used. This

can be substantiated

_by

the decrease in both the _granularity and acutance and

21

the decrease in the _{covering power,} which agrees with Altman and Henn's results.

The difference between the filtered and sludged used solutions agrees with

22

Barnes'

results,

"

in that

_increasing

solution-physical development improved

both _granularity and acutance and _{decreased covering} power. The logical con

flict in relation to acutance in these statements again suggests the _possibility

of _slightly different mechanisms _operating in each case. This difference in

mechanisms _may be expected since the above mentioned experimenters were oper

ating under different development conditions.

A possible explanation foV the increase in solution-physical development

between the sludged and filterecKgolutior.s is that removing the sludge (which

acts as nuclei for the reduction of the argentothiosulfate or thiocyanate

complexes) gives the nuclei in the image a relative advantage for the reduc

tion site.

It is _readily apparent that further basic work on this subject is neces

sary and could lead to a better understanding of monobath systems and the effect

Appendix:

1A-MONOBATH FORMULATION

Sodium Sulfite

Phenidone

Hydroquinone

Sodium carbonate

Potassium Thiocyanate

Sodium Thiosulfate

Water to make

60 grams

2 grams

15 grams

40 grams

90 grams

25 grams

F-dd-.VI

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acknowledgements:

The authors wouldlike to express their gratitude to Mr. Albert J. Derr

of the Photo and Repro Division of GAF for permission to use instrumentation

at

_GAF,

and Mr. George Giuffre of the same _company for continued

_help

through

out the entire project. We would also like to thank the United States Air

Force for use of the GAF Model 4 Microdensitometer which is _currently on loan

FOOTNOTES

1. A. Sasai and N.

_Mii,

Photg Sci. Eng. , 8: 270 (1964).

2. M.

_Levy,

..Phot. Sci.

Eng.,

2: 136

(1958).

3. Sasai and Mii.

4. Ibid.

5. Ibid.

6.

Ibid.

7. Ibid.

8. Ibid.

9. D. R. Kazen and M. F.

_Wolnick,

Phot. Sci.

Eng.,

6: 241 (1962).

10. J. C.

_Barnes,

G. J.

_Johnston,

and W. J. Moretti, Phot. Sci. and

_Eng.,

8: 312 (1964).

"May

and Baker

_Simprol,

A Variable Contrast Monobath,"

Brit. Jour, of

Phot.,

Feb. (1963).

Levy.

11.

_"May

and Baker Simprol."

12.

_Barnes,

_Johnston,

and Moretti.

13. J.C.

_Barnes,

Phot. Sci. and Eng. , 5: 204 (1961).

14.

Barnes, Johnston,

and Moretti.

15. Ibid.

16. Ibid.

17. J. H. Altman and R. VJ.

Henn,

Phot. Sci. and

_Eng.,

5: 129 (1961).

18. Sasai and Mii.

19. T.

_Celio,

Phot. Sci. and

_Eng.,

5: 12 (1961).

20. James and

_Higgens,

Fundamentals of Photographic _Theory, p. 288.

BIBLIOGRAPHY

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J. H. and

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R. W. "Effects of Developer Composition on the

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Phot. Sci/ and

_Eng.,

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(May-June,

1961).

~

Barnes,

J.C. "Mechanism of Development in Monobaths

_Containing

Thiosulfate

Ion",

Phot. Sci. and _Eng.. 5: 4

_(July-Aug,

1961).

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J.C, Johnston,

G.J. , and

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W.J. "The

Chemistry

of Monobaths:

Effect of Thiosulfate Ion Upon Image Structure,"

Phot. Sci. and Eng. ,

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_(Nov-Dec,

1964).

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tzhe

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Marilyn. "Combined Development and Fixation of Phtographic Images with

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