BTTB DEVELOP SAME FILM OVER AND OVER AGAIN TO GET MORE FILM SPEED.

Camerashy

Camerashy

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There is a guy over on flikr that uses an improved version of Barry Thorntons2 Bath. Rudiger Hartung develops APX 100 at iso1250 in BTTB, he develops the film four times before fixing it.
BathA 4mins 30 secs Bath B 4mi s 30 secs
First cycle
4' 30" A then 4' 30" B, water stop, full wash
Repeat x4 wash and fix.

Can you only do this with a 2 Bath developer?
 
I suspect this is the way you have to go with 2-bath setups if you want to push film, because they don't necessarily respond to leaving the film in longer like normal developers do (i.e each step is done to completion). So in effect is this not just the same as giving a film a huge increase in development time and hence getting a roughly 3-4 stop push?
 
Dave_P said:
I suspect this is the way you have to go with 2-bath setups if you want to push film, because they don't necessarily respond to leaving the film in longer like normal developers do (i.e each step is done to completion). So in effect is this not just the same as giving a film a huge increase in development time and hence getting a roughly 3-4 stop push?
Click to expand...
18m in Bath A and 18m in bath B is it the same as doing x4 4m 30" cycles? That would be an interesting experiment. I wonder if you would just block up the shadow details and blow out the highlights. Rudiger's photos look OK but I have no idea if they have been digitally manipulated.
 
The time in bath A has to be long enough for the developing agents to diffuse into the emulsion, their will be a point of equilibrium where the emulsion has absorbed a level where any further absorption will be balanced by diffusion out of the emulsion.

So no, increasing the time in Part A will gave no effect once that balance point is reached. A more concentrated Part A would be one option, this would be similar to repeating the cycle. You would just increase the amount of Metol in Part A, leave the Sulphite the same.

Ian
 
If there’s no fix used between successive development cycles, then there may be some residual halide crystals remaining undeveloped after the absorbed developer from bath A is exhausted. That may then be available for a second round of part A to develop. And so on…
I don’t know if part B has any neutralising effect on un-converted halides, but presumably not.
 
In the very late 1920s into the 1930s there was a major step change in the way photographers developed films, and also exposure. This was a result of the introduction of the Leica and later Contax, also high quality 120 cameras, like the Super Ikontas and Rolleiflex,and by the mid 30s small light meters. This is best read about in Hans Windisch's book "Die Neu Foto Schule" also published in English as "The New Photo School".

Essentially to get the best out out of miniature formats the old approach of over exposure and developing in Pyro or relatively high contrast MQ developers had to change. To achieve finer grain, and greater sharpness softer working developers were needed and better exposure control. At the same time Ilford introduced the first of their modern films Fine Grain Panchromatic & Hypersensitive Panchromatic, the forerunners of modern FP4+ and HP5+. There were similar film improvements with Agfa, and Gevaert..

So we no longer expose and develop our films to achieve a high D max. Printing papers also evolved to match the newer working techniques. That means there is exposed but undeveloped silver halide in a developed film before fixing.

Ian
 
I can recall a host of articles on miraculous developers for Leica owners.
Headlines might read something like “5x4 quality from 35mm.”

Has anyone else wondered why someone might start with 100ASA film to achieve 1250?
 
David M said:
I can recall a host of articles on miraculous developers for Leica owners.
Headlines might read something like “5x4 quality from 35mm.”

Has anyone else wondered why someone might start with 100ASA film to achieve 1250?
Click to expand...
It might be all they had on hand or they wanted to carry out an extreme test to find the limit of what’s possible.
 
David M said:
I can recall a host of articles on miraculous developers for Leica owners.
Headlines might read something like “5x4 quality from 35mm.”

Has anyone else wondered why someone might start with 100ASA film to achieve 1250?
Click to expand...

There may be some Physical development taking place, Sodium Sulphite is a Silver solvent, this can have an intensifying effect. Pre-WWII articles claimed quite a boost in film speed, and fine grain, with Physical developers, but most sources state they don't work with modern films.

While BTTB Part A is not a Physical developer itself, the effect of repeatedly placing a (partially) developed negative in it, then activating the developing agents again in Part B, then washed to remove spent by products, may have the same effects.

Kurt Jacobson lists a Kodak Two Bath Developer in the 1940 first edition of, Developing, he notes that Part A contains 100g Sugar (cane) and 5g Sodium (Meta)bisulphite), this is to inhibit ant slight development due to the slight alkalinity of Sodium Sulphite.

Ian
 
Kodak published an Silver Intensifier IN-5, essentially it's Silver Nitrate, Sodium Sulphite. Hypo, and Metol, stored as 4 solutions, with a 30 minute tray life once mixed.

I've never looked closely at the chemistry of physical development. it's about 50 years since I began researching things like fixing, which is not chemically simple, with a great many equilibrium complexes formed before completion, and the more dissolved Silver the less effective in terms of archival permanence.

Ian
 
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