There are many
developers available for black and white photography; The choice is
bewildering and ready made concentrates are expensive. However, anyone
having a chemical balance can have fun mixing home brews and is able
to make up developers not available commercially. Those members who
occasionally indulge in black and white photography may be interested
in the following account of my experiments using the two bath process
of negative development.’
Way back in
1938 Heindrick St÷ockler devised two bath development of slow and
medium speed films. He found that by immersing a film in a developing
solution which excluded the alkali, the emulsion became saturated with
developing agent without showing more than a trace of image. After a
few minutes the first solution was drained off and filtered back to
its bottle. Then the second bath of alkali solution was poured into
the tank to complete the development of the film. The resulting
negatives were of low contrast with even separation of tones - ideal
for the then relatively new roll films exposed on subjects of varying
brightness ranges. St÷ockler also found that, due to the surface
action of the process, his negatives had fine grain and high acutance.
The two bath process became popular in the post-war years and
especially so with photographers who preferred high contrast lighting.
Eventually, however, highly concentrated liquid developers became
fashionable and consequently home brews lost favour. Nowadays, more
and more people are turning to black and white photography and many of
the old processes are being tried again. Two bath development of
modern thin emulsion films produces negatives which are very easy to
print on variable contrast paper.
My experience
with black and white chemistry extends over more years than I care to
admit. During the years since the war I have tried many films and many
developers. In the late 60`s` my interest in the two bath process was
revived when I read an article on the subject by Ron Spillman. He
extended the process to include films in the ISO/ASA 400 group by
increasing the amount of metol and reducing the amount of sulphite in
the first bath. Spillman`s Resofine 2B, as he called it, is still
available from Speedibrews. Tetanal also sell an all liquid or powder
version of their two bath developer called Emofin which is useful for
those who do not wish to weigh and mix chemicals themselves. In my
opinion, the two bath process is outstanding. It is very simple to
mix, it is not at all critical of time or temperature and it produces
very clean, nicely graded negatives having fine grain and excellent
sharpness. Although the original conception was to produce negatives
which would handle high contrast subjects, the negative contrast can
be varied to suit the needs of the photographer. Increasing the time
in the first bath raises the density of the highlights. I have
experimented with formulae with a view to extending the useful life of
the first bath and to devise a one-shot system for the second bath to
overcome the problem of carry over from the first to the second bath.
Metol is
usually the sole developing agent but I have found that in combination
with hydroquinone, oxydation in store is retarded. Also, there is some
benefit from the superadditive effect of the two developing agents.
After trying M.Q. Borax developers, such as ID-11, and separating the
borax into the second bath, I settled for the formula given below.
Phenidone was also tried as a replacement for metol but this proved to
have no advantage at the low levels involved.
In trying out
several mild alkalis as concentrates I found sodium carbonate to be
more suitable than borax. However, sodium metaborate (Kodalk) proved
entirely satisfactory. Incidentally, the action of the second bath is
carried out to completion. Negative density is determined by the first
bath.
Two Bath
Formula
Bath A
Bath B
Water @ 40OC
400ml
Water @ 40OC 400 ml
Metol
2.5 gm
Sodium metaborate 20 gm
Sodium sulphite, anhydrous
30 gm
Water to
500 ml
Hydroquinone
1 gm
Water to
500 ml
Bath A is used
at full strength and filtered back into the bottle after use. Bath B
is diluted 1:9, used once and discarded.
NB. If sodium
metaborate is unobtainable substitute 2.6 gm sodium hydroxide plus 6
gm of Borax.
Suggested times
for 20OC +/- 1OC with two inversions every 30 secs in Bath A and 2
inversions to commence followed by two inversions at half time in Bath
B.
Film Speed
ISO25/80
ISO 100/200
ISO 400
FP4+, Delta 100,
Trix-X
Film Types tested
Pan F
KB100, KB200,
Delta 400
to date
KB50
T-Max 100
T-Max 400
Bath A
3 mins
4 mins
5 mins
Bath B
3 mins
4 mins
5 mins
DO NOT rinse between baths A and B.
NB. The
above times are suitable for an enlarger with opal bulb and
condensers. For diffuser types increase time in Bath A by about one
third.
Use your
usual method for stop, fix and wash but allow film to dry completely
before assessing the negatives.
So! why
not try this simple process? When using club chemicals it costs about
5p per film and you will be rewarded with negatives which are very
easy to print, even those of subjects taken in flat lighting ù just
use a more contrasty filter setting. I would like you all 2B trying 2B
in the near future.