MONOCHROME
TRANSPARENCIES
By Terry Hardy (Area 22)
I
was interested to see reference in the Newsletter to reversal processing
of B&W film. I have been making monochrome transparencies for a
number of years now, along with colour of course, and the results can be
very pleasing. In my experience the best results are obtained from using
a slow or moderate speed film. I normally use FP4 or KB100. The faster
films come out slightly lacking in contrast. If I remember rightly the
processing formulae are quoted in the "Ilford Manual", mine
seems to have gone missing at the moment, but I have a separate note and
append the details below –
REVERSAL
DEVELOPER (Stock Solution)
Metol
3gm
Sodium Sulphite Anhydrous
50gm
Hydroquinone
12gm
Sodium Carbonate Anhhydrous
60gm
Potassium Bromide
4gm
Water to
1000ml
Dilution (Sock + Water)
1 + 1
To
the diluted working strength developer add Sodium Thiosulphite
anhydrous. For FP4 and KB100 add 7.5gm per litre
BLEACH
(two part stock solutions) SOLUTION A
Potassium Permanganate
2gm
Water to
500ml
SOLUTION
B
Sulphuric Acid 10% v/v
100ml
Water to
500ml
These
stock solutions will keep indefinitely, but deteriorate rapidly when
mixed. Mix equal parts of A and B and discard after each film.
CLEARING
BATH
Sodium or Potassium Metabisulphite
25gm
Water to
1000ml
PROCEDURE
1. First Developer: 12 min @ 20C
for FP4. Invert tank every 15 sec. Retain
developer for second development.
2. Wash:
3 min. with frequent changes.
3. Bleach:
5 min. with continuous agitation.
Room lights may now be switched on.
4. Wash:
2 min. with frequent changes.
5. Clear:
2 min. in Clearing Bath.
6. Wash:
2 min. with changes.
7. Reversal Exposure: Film should preferably be on transparent spiral.
Re-expose each end of spiral for 3 min. to No. 1 photoflood, with spiral
immersed in bowl of water.
8. Second Developer: 8 min. @ 20C in solution retained from First
Development.
Rinse
10. Fix: In hardening fixer for 10
min.
11. Final Wash:
Wash for 30 min. and dry.
Camera exposures have to be more or less spot on, as the process gives
very little latitude for over or under exposure, but the final results
can be quite superb, and the effort involved is well repaid; at least I
think.
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