Using two bath developers

The clue to a fine monochrome negative is to give so much exposure as to give rich detail in the shadows, and so little development as to avoid highlights becoming too dense to print with subtle graduation. The vast majority of the negatives arriving in the Fine Print Photographer's Workshop have been underexposed and overdeveloped making a fine print an impossibility This applies to amateur and professional, novice or expert, using ultra modern sophisticated cameras or old fashioned basic cameras. Actually, it is less common with people using simple older cameras.

Two bath development is far from new. Heinrich Stockler recommended a formula before the second world war that was popular with Leica users, and it still works really well today. Ansel Adams did not invent, but used and publicised a different formula based on Kodak D23 that also worked well, especially for larger format negatives of high contrast subjects. It is hard to understand why the process is not more widely used. There are a couple of proprietary versions. The American Diafine is very well proven in its speed enhancing properties, but is not widely available in the U.K. Tetenal make Emofin which also increases the speed of some films, but rather defeats one of the great benefits of two baths by requiring different times for different films. The formulae given below allow one to process different makes and speeds of film together for very similar times, and you can use the same at a pinch and still get acceptable negs. They are not fussy about time and temperature within reasonable limits, they have outstanding capacity, they keep well, they are sharp and fine grained, and they are very low cost. All of these factors make two bath development attractive anyway, but they miss the main benefit.

If you use sheet film, and are a careful worker, you can expose and develop each sheet individually by zone system procedures to produce the best negative possible to allow production of fine prints. If you use roll film, unless you very carefully group all pictures of the same subject brightness range on to the same roll, you cannot give appropriate development to each exposure and some compromise development has to be given to the whole roll. If the subject brightness range for each picture is low, this isn't too much of a problem since the latitude of the film will normally allows a good quality, if not fine, print to be made. If, though, the subject brightness range exceeds the film's range (and it often does) or exactly matches it, then there is no latitude even if the exposure is exactly right with the use of a precisely calibrated spot meter. If a camera's automatic meter is used, then it is highly likely that the exposure varies from the ideal no matter how sophisticated it is supposed to be, especially if the effective film speed has not been ascertained by personal test.

What two bath development does is to try and compensate for these variables in each individual negative automatically to produce full toned negatives that print more easily for high quality. This means that a negative of a low contrast subject continues to develop up to produce a good printing contrast, while, more importantly, negatives of high contrast subjects have the highlights held back while the shadows continue to be built up so that detail can be printed easily at both ends of the scale. All this happens automatically for different films developed together for the same time. The technique is the same for all versions of the two bath. Bath A contains only the developing agents and preservative and sometimes a restrainer. Bath B contains the accelerator, and sometimes a restrainer. The film is 'developed' in Bath A with agitation every half or full minute -it's not critical. Actually little development takes place. Mostly the film is becoming saturated with the developing solution. However, some development does take place and agitation is important to prevent streaking. The solution is then poured off and saved. Drain the tank well but don't rinse or use a stop bath. Then pour in Bath B, and after a quick rap of the tank on a hard surface to dislodge any airbells, let the tank stand still with no agitation for three minutes or so when all development has ceased. Note, though, that while no agitation is ideal, and usually works well for unsprocketed roll film (120/220), there can be streamers from 35mm sprocket holes. This seems to vary with different kinds of tanks, different films, and the local water characteristics. Do your own experiments to determine the minimum agitation you can achieve without streaking before committing a crucial film to the process. Perhaps try one minute intervals to start with.

In the second bath the developer soaked into the film emulsion is activated by the accelerator. In the highlight regions where the developed silver will be densest, the developer available in the emulsion is soon exhausted and development halts, thus automatically limiting the density of the negative at that point. The more the exposure, and the denser the highlight, the faster development ceases. In the shadows, though, there is little silver to reduce and there is enough developer to keep working there to push up the shadow detail density. The less light the negative received at this point the longer the development proceeds. Indeed there is a minor hump put into the characteristic curve of many films between the shadow and mid tones to give heightened shadow contrast. The effect is not the same as the well known technique of compensating development by diluting developers, which does work in holding back dense highlights, but can give muddy mid times and does not have the same automatic contrast equalisation as the two bath. Of course there is a limit to the contrast that can be equalised, but most negatives will print to good quality on 2 or 3 grades of paper with only the most extreme contrast range subjects requiring other contrast control methods for printing. For the very economical chemicals and scales one source is Rayco at 199 King Street, Hoyland, Barnsley S74 9LJ.

The Stockler formula

Bath A	grams	Bath B	grams
Metol	5	Borax	10
Sodium Sulphite	100
Water to	1 litre	Water to	1 litre

Try about four minutes in each at about 21C

The Ansel Adams D23 formula

Bath A	grams	Bath B	grams
Metol	7.5	Sodium Metaborate	10
Sodium Sulphite	100
Water to	1 litre	Water to	1 litre

Try about three minutes in each at about 21C for roll film; four for sheet film

The Barry Thornton higher definition formula

Bath A	grams	Bath B	grams
Metol	6.25	Sodium Metaborate	12
Sodium Sulphite	85
Water to	1 litre	Water to	1 litre

Try about four minutes in each at about 21C for roll film; five for sheet film.

The Stockler formula is very soft working and gives very fine grain. With today's thin emulsion films which do not 'soak up' as much of either Bath A or Bath B, thus resulting in less development activity, it can be too soft. Beware, too, of the second bath's very mild alkali s losing effectiveness. You may need to refresh it with extra borax from time to time. You do not need special photographic chemical grade for this. The anhydrous type freely available from High Street pharmacists will be fine. The Ansel Adams formula is quite 'robust', and you should beware too high a contrast on roll film - cut times if necessary. My own formula is somewhere in between for contrast, has extra acutance, and does not suffer the second bath exhaustion to which the Stockler mix is prone. You should get at least 15 roll films through my formula, and more if you then refresh the second bath with more sodium metaborate.

The Teaspoonful Two Bath
As far as I know nobody has mentioned another technique which I have evolved and which works really well to give different tonal characteristics and very similar automatic contrast control, and to avoid having to mix anything but an approximate Bath B - two heaped teaspoons of sodium metaborate in 1 litre of water. It dissolves almost instantly and is cheap enough to use once then throw away, though it would handle 15 roll films if re-used. Simply use your normal standard developer (T-Max, ID11, llfotech, HC110, Econotol, Perceptol etc.) for half to two thirds of the maker's stated time as Bath A, drain it off, and use the teaspoon-measured Bath B for 3 minutes at the same temperature as Bath A. You may have to fine tune Bath A time by experience. For all 2 baths stop and fix afterwards in the usual way after Bath B, but not between the two baths Copyright Barry Thornton.

About the author
Barry Thornton sadly died on 25 Oct 2003. Barry ran the Fine Print Photographer's Workshop in Chepstow where he patiently coached professional and serious amateur photographers to a true understanding of the making of fine monochrome photographs. His book, Elements, distills a lifetime's technical experience and feelings about the art of photography. He received recognition in the Ilford Awards, and ran occasional Masterclasses for them. He evolved several highly specialist developers and processing solutions, which can be bought from www.barrythornton.com.