DETERMINATION OF OPTIMUM PAPER PROCESSING
We'll start at the end of the process. First, we'll determine the paper
processing, then the paper exposure, then the film processing and finally
the film exposure.
There is no universal paper processing time. It varies according to
the type of paper you use, the type of chemicals that you use, your processing
method and equipment, the temperature, dissolved chemicals in the water supply,
and many other factors. If you use the processing times that someone
else recommends, you are probably not getting the best results that you can
since their situation is not exactly the same as yours. Little differences
in these factors can lead to big differences in your results.
There are no special tools needed to complete this set of tests. However,
some test solutions are needed. These can be purchased commercially
or mixed yourself. In addition, it is strongly suggested that you use
tubes for processing instead of trays. Not only are tubes easier on
your health (less fumes), but they are easier on your wallet (you mix a lot
less chemicals when you use tubes). Most importantly, for the best,
consistent results, tubes can't be beat. With trays, the only paper
that gets fresh chemicals is the first piece of paper. All subsequent
pieces of paper get a diminished development to an unknown extent. With
tubes, every piece of paper gets nothing but fresh chemicals. Tubes
also make these tests easier and more accurate.
1. Select any type of B&W or color enlarging paper. The tests must be
re-run for each type of paper that you plan to use, or if you use toning
or other special techniques.
2. First, you need to determine the correct fixation time for the paper.
Test for proper fixation (the removal of all unexposed silver by the
fixer), as follows
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A. Fix, wash and dry an unexposed, undeveloped sheet of the selected paper
using any desired fixer, time and dilution. Normally, it is best to start
with the manufacturer's recommended time and dilution rate.
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B. On the emulsion side of the paper, apply one drop of Rapid Selenium Toner
concentrate.
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C. Wait two minutes.
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D. Any yellowing indicates residual silver. Increase the amount of time in
the fixer and retest until no yellowing is noticeable..
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E. Test for exhaustion of the fixer, as follows:
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1. Take two oz of the used fixer.
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2. Add two drops of test solution such as Hypocheck:
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potassium iodide 0.01g
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water 0.05ml
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F. Shake.
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G. Wait two minutes.
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H. The solution should be clear. If it displays any milkiness, the fixer
is exhausted -- decrease the dilution of the fixer and run the test again
using a sheet of paper.
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I. If the fixer clears and no yellow stain appears on the paper, the test
is passed; increase the dilution of the fixer and repeat the test until it
fails.
3. Test for proper washing of the paper (the removal of all the fixer from
the paper during the wash step), as follows:
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A. Expose, develop, fix, wash and dry a sheet of the selected paper using
any desired exposure and developer combination. Use the fixation procedures
determined above.
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B. On the emulsion side of the paper place one drop of test solution:
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water 1.30ml
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acetic acid 0.05ml
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silver nitrate 0.01g
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C. Wait two minutes.
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D. A barely visible or no stain is best. Continue washing if a stain appears
and retest. Try using a washing aid , such as PERMAWASH, to reduce the washing
time.
4. Light from OUTSIDE the darkroom is sometimes responsible for fogged
photographic paper. Test for darkroom light leaks as follows:
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A. With the darkroom door closed, turn off all the lights, including the
safelights.
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B. Wait for 5 minutes, so that sensitivity to light will be very acute.
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C. Move around the room and tag any light leaks with a pencil or Post-it
notes.
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D. Plug any light leaks with weatherstripping, felt, tape, etc.
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E. Retest the darkroom for light leaks.
5. Light that is bright enough to fog the paper can escape from even the
best-designed enlarger. Test for enlarger light leaks as follows:
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A. Set the enlarger to the height for an 8x10 on the desired film format.
You can use any other enlarger height, as long as it is a standard height
for your purposes. If fact, it is a good idea to make a mark on
the enlarger column at this point since you will need to set the enlarger
at this same height for several other tests.
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B. Select the best lens for the format.
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C. Use a scrap negative to focus the lens.
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D. Remove the scrap negative.
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E. Stop down the lens 2 f-stops.
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F. Completely cover the enlarger with a black plastic garbage bag.
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G. Tape the opening of the bag around the sides of the lens so that any possible
light leaks from around the lensboard will be covered.
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H. Turn all lights off, including the safelights.
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I. Place a sheet of the paper to be tested in the easel.
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J. Cover 1/2 of the paper with an opaque card.
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K. On the uncovered half of the paper, make a test strip from one second
to the longest possible exposure time that would likely be used, such as
1, 2, 4, 8, 15, 30, 60, 120, 240, 480 and 960 seconds. You might want
to extend this range if you make extra-large prints, or shorten it if you
only make small prints.
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L. Develop, fix, wash and dry the paper using the manufacturers recommended
paper processing scheme.
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M. Find the longest exposure which still produces pure white (no greying).
Compare the strips to the side of the paper that was covered by the opaque
card. It might be a good idea to run a fine-tuning test strip. For
example, if 30 seconds still produces white but 60 seconds does not, you
can run another step table between 30 to 60 seconds.
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N. Expose another sheet of paper at the final setting that produces pure
white. Leave the paper in the easel after the exposure.
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O. Remove the plastic bag from the enlarger.
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P. Cover the front of the lens with a lens cap or other opaque object.
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Q. Cover 1/2 of the paper with an opaque card.
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R. Keep the lens cap on the enlarger and make a test strip from one second
to the longest expected exposure with this type of paper. The paper will
not receive any direct light, just light leaking out of the enlarger.
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S. Develop the paper according to the manufacturer's recommendation. Fix
and wash as determined in earlier tests.
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T. Check the results. All the strips should appear pure white when compared
to the section of the paper covered by the opaque card. Any greying (or with
color paper, any tone) of the strips means that light is leaking out of the
enlarger and fogging the paper.
-
U. Fix any light leaks by painting the surrounding walls and ceiling black
and by gluing black felt strips or flaps over spaces and cracks in the enlarger
itself. DO NOT COVER ANY AIR VENTS ON THE ENLARGER. Don't be surprised if
even an expensive enlarger has many leaks.
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V. Retest the enlarger until no difference can be found between the test
strips.
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W. Note the maximum amount of time that the enlarger can be on without darkening
the image. Keep all future exposures under this time limit.
6. Test for mottling from too short a paper development time.
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A. Set the enlarger to the height for an 8x10 on the desired film format.
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B. Select the best lens for the format.
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C. Use a scrap negative to focus the lens.
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D. Remove the scrap negative.
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E. Stop down the lens 2 f-stops.
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F. Turn off all lights, including safelights.
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G. Expose a sheet of high contrast paper (or multigrade paper with a high
contrast filter) to produce a mid-grey tone. An appropriate exposure
time can probably be determine from the previous test. The exact tone
is not important.
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H. Process the paper using a 30 second development time. Fix and wash the
print, as determined in earlier tests.
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I. Any mottling in the print means the development time is too short.
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J. If there is no mottling, decrease the development time. But more
than likely there will be mottling. In this case, expose another sheet
and increase the developing time. Fix and wash the print, as determined
in earlier tests. How much to increase the development time is up to
you. Start out by doubling it. If the mottling disappears, then
decrease it somewhat. The goal is to find the shortest time that minimizes
mottling. Since the test uses a high contrast paper, the appearance
of mottling may never disappear completely. But don't go over-board.
As with all of these tests, there is no need to gets the exposure down to
the a precise millisecond -- you will never notice the difference! It's
best to have a longer development time to make sure that mottling will not
occur.
-
K. With many papers, anything longer than 60 seconds is OK. Recheck
your results if you change your processing technique, such as switching from
tubes to trays, etc.
7. Test for fog from too long a development time.
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A. Turn off all lights, including the safelights.
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B. Cut an 8x10 sheet of paper into 1 inch strips.
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C. Fix and wash an unexposed, undeveloped strip of paper as determined in
the first tests. This will be your comparative strip with no development.
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D. Develop each additional strip for 1, 2, 3, 4, 5, 6, 7, etc. minutes.
Then fix and wash, as determined in earlier tests.
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E. Compare strips. Any greying, even a little, indicates fogging due to too
long a development time. With most papers, usually anything less than five
minutes is OK. Run fine-tuning tests if you think they are appropriate.
8. Select a development time which does not create mottling nor fog. Let's
say you have no mottling at 2 minutes, and no fog at 5 minutes. Longer
development times will give shorter exposures under the enlarger, while shorter
development times will require longer exposures. Normally, shorter development
times -- with their requisite longer exposure times -- is the best way to
go. This will generate the greatest total amount of saved time because the
most time-consuming part of the process is developing. It will also give
more time for dodging and burning due to the longer exposures. This should
also make the use of wider apertures -- less diffraction -- easier to achieve.
The shorter development time forces the lens to be "opened-up" as more light
is needed to compensate for the shorter development.
Although some authors suggest that changes in development and exposure of
photographic paper lead to changes in the contrast of the print, this is
just another myth of photography. Henry's experiments
(Controls in Black and White Photography)
refute this; but don't take my (or his) word for it -- test it out yourself
or check out his book at the library.
9. Too powerful or too close a safelight can ruin an otherwise great print.
Test for safelight fogging of the paper.
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A. Set up safelights at desired locations and brightness.
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B. Turn safelights off.
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C. Set the enlarger to the 8x10 height for the selected film format.
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D. Select the best lens for the format.
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E. Use a scrap negative to focus the lens.
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F. Remove the scrap negative.
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G. Stop down two f-stops.
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H. To test pre-exposure safeness -- how long the paper can be exposed to
the safelights before the main exposure -- place a sheet of the paper under
test under the enlarger and cover it with an opaque card suitable for making
test strips.
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I. Turn the safelights on.
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J. Make a test strip of decreasing exposure to the light of the safelight
alone. Start with the longest exposure time likely to be used. If a timer
is used, set the timer for this time period with the enlarger turned off.
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K. Cover up the entire sheet of paper.
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L. Turn off the safelights.
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M. Uncover the sheet and expose the entire sheet to the threshold setting
determined in step 5M. This is the maximum exposure which does not cause
any greying in the print.
-
N. Cover the paper with the opaque card once again.
-
O. To test post-exposure safeness -- how long the paper can be exposed to
the safelights after the main exposure -- set the timer to the longest time
the paper would be exposed to the safelight after the exposure (including
processing time in the developer if trays are used).
-
P. Superimpose a test strip for post-exposure safeness over the pre-exposure
test strip to determine combination effects. Make a test strip as before
decreasing the time by one half and exposing a new strip to the light. However,
for this test strip, uncover the paper perpendicularly (how do you pronounce
that?) to the first test strip.
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Q. Cover the print with an opaque card.
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R. Turn the safelights off.
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S. Develop, fix and wash the paper, as determined in the last test.
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T. Find the longest pre- and post-exposure times which does not produce any
greying. Do not handle prints for longer than these times.
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U. If the maximum times produce too much exposure, decrease the wattage in
the safeflights, increase the distance between the safelights and the paper,
replace the filter in your safelight, or buy a more effective safelight..
10. The reciprocity rule can mess up paper exposures just as it can ruin
film exposures. Test for reciprocity rule failure in the paper.
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A. Set the enlarger at the 8x10 height.
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B. Set the lens at the maximum whole f-stop.
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C. Focus the lens with a scrap negative and then remove the negative.
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D. Make an test strip exposure to determine the time needed to produce any
mid-grey tone. The tone does not have to be exactly mid-grey.
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E. Develop, fix and wash the paper according to the results from the previous
tests.
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F. Stop down the lens one f-stop and double the exposure time on another
peice of paper.
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G. Develop, fix and wash the paper according to the results from the previous
tests. The tone should be the same as on the original mid-tone image.
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H. Continue stopping-down and doubling the time until a lightening of the
print is noted or there are no more f-stops available. For more accuracy,
or for extending the effective f-stop range of the lens, use neutral density
filters instead of stopping down the lens.
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I. Note the first exposure time that results in a lightening of the image
tone. Keep all future exposures under this limit. A lightening of the
print does not automatically mean reciprocity rule failure; the difference
could be due to inaccuracies in the lens aperture settings -- but either
way these settings should be avoided.
Now that you know how to correctly process the paper, you're ready to move
on to DETERMINATION OF OPTIMUM PAPER EXPOSURE.
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contact the Sub Club at the FRONT
DESK.
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COPYRIGHT @ 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 by Joe McGloin. All Rights Reserved.