Appendix 3
Recovery techniques for black and white Negatives
You get beck from your trip and your B&W negatives look
awful when you try to print them? What can you do? First you have
to work out the nature of the problem. Did you expose wrongly
or develop incorrectly? Ask an experienced darkroom worker to
help you work out the source of the problem. PhotoAccess staff,
PhotoAccess tutors or members of the Canberra Photographic Society
are good sources of experience in this area.
Under developed negs
Use an intensifier. This is a chemical that makes the negative
appear to be denser. Chromium and Selenium solutions are normally
used.
Over developed negs
Use a reducer. A reducer is a mixture of potassium ferricyanide
(ferri) with another chemical. Don't use ferri directly or you
will make the neg quite unprintable.
An excellent description of the use of intensifiers and reducers can be found in The Elements of Black & White printing and should be read before attempting this type of work.
Scratched Negatives
Nose grease. Wipe a little grease off the crease of your nose
and massage it in to the scratch so that you don't leave fingerprints.
If this doesn't work, try Vaseline or other petroleum jelly or
a very expensive liquid called "Repolisan" made
by Tetenal. Both vaseline and nose grease have to be washed off
the negative after printing, as they will attack the negative.
Repolisan is a permanent resurfacing agent. The stabiliser from
E6 slide processing can also be used to resurface & fill scratches.
This is the only substance that can be used to repair scratched
transparencies.
Damaged negatives
1. Scan the negative into the computer and digitally repair
the damage. Send the file to a bureau to be rewritten as a negative.
2. Print a large version of the print (12" x 16"). Use
retouching & collage techniques to restore the damage
Printing difficult Negatives
The most important thing is to work methodically. Guessing is
not an option. All the best printers I've met work in a very methodical
manner. By keeping good record of what you are doing, you can
backtrack if you take a wrong turn.
Dealing with is a bright sky is one of the most common problems
encountered in printing.
Burning and dodging
Test strips should be made in the sky and the ground so that
you can work out exactly how much burning and dodging is required.
Let's use a difficult sky as an example. Using test strips on
the foreground and sky you see that the sky needs 40 seconds and
the fore ground needs 10 seconds. Then make a 10 second exposure
over the whole print and then a further 30 seconds on the sky.
For a detailed horizon, make a cut out from a print and place
it against the paper. Make sure that the paper is firmly held
by an easel. For a sky that gradually brightens toward the horizon,
use a straight piece of card and slowly move it towards the top.
Split contrast printing
Split contrast printing is a technique that involves exposing
different parts of a print to different filters. Let's use the
difficult sky photo as an example. You determined that the foreground
required 10 seconds and the sky 40 seconds with a grade 3 filter.
Unfortunately, when you burned in the sky with grade 3, it looked
really dull and grey. The trick is to expose the foreground with
the grade 3 filter but put some life into the sky with a higher
grade filter.
Take a generously proportioned test strip; Place the test strip in the sky area of the image parallel to the horizon and include the horizon. From your first test strip, you know that you are going to expose the print for 10s with a grade 3 filter. Expose the whole test strip for 10s with a grade 3 filter then turn off the enlarger - no covering. Carefully remove the Grade 3 filter and put in a higher contrast filter like a #4 or #5. Don't bump the enlarger or you will get double imaging.
Now do another test strip with the extra exposure coming from the grade 5 filter. Select the exposure that you want let's say it was 40 s with a grade 5.
Making the final print
Put the # 3 filter back in the enlarger and a whole sheet
of paper. Expose everything for 10s with the grade 3 filter. Carefully
remove the Grade 3 filter and put in the #5 filter. Reset the
timer to 40 seconds; take a burning card and cover the horizon
as you begin the 40 second exposure.
Hint : gradually burned skies look better than constantly
burned skies. About half to three quarter way through the burn
in exposure, begin moving the card from the horizon to the top
of the print.
Pre-flashing
Pre-flashing is a technique for reducing contrast by giving all or part of the paper a tiny exposure of white light before the image is placed in the enlarger. This helps dense parts of the negative to print through and at the same time does not change the shadows at all.
Take the negative out of the enlarger, stop the lens down to minimum and do a test strip with 1,2,4,8,16 second exposures. One of these will be pure white and the next will just start to render a grey tone. Note down the time and f-stop of this exposure. Every test strip and print you do from now on must have this pre-flash exposure before you insert the negative. Beyond this point work methodically as in the methods described above. Pre-flashing split contrast printing and burning and dodging are often used in combination as tools used to control excessive contrast.
Grade 7 paper. What do you do when Grade 5 isn't enough?
While dealing with excessive contrast is a frequently encountered
problem, occasionally you will take a photograph in very flat,
dull lighting conditions. XP2 negatives taken in normal lighting
can also be very flat.
In Camera
If you recognise the problem when you are taking the shots,
you can double the film speed and push process the film. You must
shoot the entire film in dull light and push process the whole
film for that light. This won't work for chromogenic films like
XP2.
In the Darkroom
So you've tried a grade 5 filter and it still looks dull.
Test strip the darkest parts of the print and print so that the
shadows print to just a solid black. The highlights will appear
too dark. We will deal with this at the next step.
Put the print in the water for 2 minutes and keep the whole
print under the water all the time. Place the print in the ferri
and agitate. When the highlight looks almost light enough remove
from the ferri, drain, quickly wash in water then place in the
fixer. The trick is to remove it from the ferri before it looks
right so that you have time to drain, wash and fix. The print
will continue to bleach during this process so you must remove
it before it is adequately bleached. This is why you made 3-4
copies of the print. It's quite hard to get this right in one
go and it usually takes me 2-3 attempts to get it right.
| Webmaster : Joseph A. Cali Send all comments to Joe Cali at joe_cali@hotmail.com Last modified 1st July, 2000. |