"Icius" wrote in message
om...
Hello All,

I have been studying Ansel Adams' three excellent
photography books
and trying to plan some things for a darkroom I am
building. I was
reading the "Roll Film Processing" section in "The
Negative". Most
places online indicate that one tank is used and chemicals
are dumped
out and replaced by the chemicals in the next step.
Ansel's
instructions seem to indicate a separate processing tank
for each
step. I think this is further clarified by the pictures
in which each
tank has a different letter on the front. I counted five
as follows:

1. Pre-soak
2. Developer
3. Stop Bath
4. Fixer
5. Hypo clearing agent

Being new at this I am trying to stay as true to Ansel's
instructions/technique as possible as a starting point. I
figure if I
follow the instructions of one of the masters it will
eliminate a lot
of initial frustration. What are all of you doing? One
tank or
separate tanks? Anyone tried both and noticed a
difference? It seems
like chemical residue in the single tank scenario could
play a part in
affecting development.


I think Adams idea here was to avoid uneven development
due to the time it takes to fill and empty the tank. Kodak
also suggests filling the tank ahead of time and putting
the loaded spool in it in the dark.
I've worked both ways and find that if the developing
time is reasonably long there is no significant difference
between putting the film in first or putting the developer
in first. The same wtih the stop bath. Certainly, the fill
and dump times are much shorter if the lid can be taken off
the tank, as it can in the dark.
It is not necessary to use separate tanks, only that the
dumping and filling be done in the dark so that the lid can
be removed from the tank, but see the last paragraph.
A couple of other things. I am not a believer in routine
pre-soaking. Its helpful for some things. Mainly, it is used
to even out the uptake of the developer by the film. The
presoak saturates the emulsion so that the developer must
displace the water by diffusion. This slows down the initial
development and can eliminate some uneveness when the
developer does not contact the film all at once. If the tank
is filled first there is really no need for the presoak.
I like to have film/developer combinations with
developing times no shorter than about 8 minutes. This
allows enough time at the beginning of development for the
developer to soak into the emulsion evenly before much
development happens. Presoaking affects mainly what is
called the induction time of development, that is the time
between the immersion of the film in the developer and the
time the image begins to appear. It is the extension of this
time that tends to even out development. The effect on
overall development time will depend on several factors
including the thickness of the emulsion and the type and pH
of the developer. It is a factor which must be discovered by
experiment, there is no formula for predicting it.
The use of multiple tanks is common when processing
large amounts of film. Nikor made tall tanks that took about
eight rolls of 120 and double that of 35mm film. These are
not really daylight tanks, the spools are on lifting rods
and are transferred from one tank to another. Once in the
tank the lights can be on and the tanks are agitated like
the small ones by inversion. The lifting rods are very often
missing when these tanks are sold.
In short, presoaking or the use of a pre-filled tank is
useful when development times are necessarily short but make
diminishing difference as the development time is extended.
There can be an effect on uniformity from the stop bath if
it is poured in very slowly. However, because the film is
already wet, and saturated by developer, the effect is much
less than the effect of uneven application of developer.
Fixing baths are used to completion so any uneveness in
application is of no consequence.
I recommend two bath fixing for both film and paper and a
brief wash between fixing and wash aid, although the latter
is really not necessary if the wash aid is not reused.


--
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Richard Knoppow
Los Angeles, CA, USA