In Article "Zone System Contraction — A New Theoretical Approach", I showed that traditional contraction methods produce negatives having insufficient local contrast in shadows and highlights. Such negatives usually print well only with extreme manipulation. I proposed that an ideal contraction negative ought to have a curve like Figure 1. Such a negative provides improved shadow and highlight contrast, while your printing paper’s straight line section will replace much of the lost midtone contrast.

There is no ideal solution to the problem of contraction. I can offer significant improvements over current methods, but there are no silver bullets. Any contrast reduction method must sacrifice contrast in all regions of the curve. My approach with the Monobath Method has been to make the majority of the sacrifice in the midtone region and gear the negative to a grade 3 or 4 paper^{footnote 1}, thereby restoring much of what was lost in the shadows and highlights.

The Monobath Method

I promised three new approaches to contraction in "Zone System Contraction — A New Theoretical Approach", each superior to conventional techniques. The Monobath Method, the subject of this article, is the most involved, but is also the most versatile.

With the Monobath Method, you can produce a curve like Figure 1, or (within limits) any curve shape you desire. You can emphasize contrast retention in the shadows and highlights, or in shadows and midtones. Presumably you will seldom want to sacrifice shadow contrast, since you can do that simply by giving less negative exposure.

The Monobath Method involves post-treatment of the negative. This makes some photographers nervous due to Ansel Adams‘s warnings against it, but none of the drawbacks normally encountered with post-treatment techniques are to be found with this technique. The Monobath Method produces extremely fine grain, very high resolution, extraordinarily even development, and absolutely no loss in film speed^{footnote 2} whether your contraction is N-1 or N-10.

The Monobath Method is not a reduction method. Instead, it involves a double redevelopement of the negative. You can use any B&W film as long as it does not have a shoulder in the usable region of its characteristic curve. I recommend T-Max 400 film for this purpose. To my surprise, T-Max 100 showed a definite shoulder starting at about Zone XI to XII. It’s a great film, but not for this method. (There’s a rumor that recent T-Max 100 batches have less shoulder. Try it for yourself).

Redevelopement has definite advantages: Give normal exposure and normal development to your contraction negatives. Redevelop only those negatives you already know are worth the effort, with regard to composition and aesthetic value. Redevelopement can be done at any time, even years after the negative was first developed.

Always shoot four to six (six is better at the beginning) negatives of each contraction subject. You’ll need some of these negatives for testing, and you may want to experiment with different curve shapes to see which you like best. If it’s a one-chance subject, shoot several dummy negatives for testing. I always contact print future Monobath Method negatives twice, once for shadow detail, and once for highlight detail. This is a great help later in determining exactly where to sacrifice contrast.

Basically, the first phase of the Monobath Method involves bleaching the image, followed by partial redevelopement in a very weak, highly compensating developer. Only (approximately) Zones I through III are fully redeveloped. The remainder of the image (midtones and highlights) are left only partially redeveloped, allowing development to be completed in another bath. At this point in the process, the film has a curve similar to Figure 2.

Following the first redeveloper, the process is completed in a monobath. A monobath is a developer that also contains fixer (sodium thiosulfate). A monobath works because its high alkalinity allows complete, or nearly complete, image development before fixation can begin.

Monobaths have several desirable characteristics. They produce extremely fine grain and very high acutance due, respectively, to the silver solvent effect and a strong edge effect, both caused by thiosulfate. Monobaths also produce extremely even development.

Most important here is one of the monobath‘s most undesirable characteristics! Experimenters spent nearly half a century trying to get rid of this fly in the ointment, which we’ll put to good use. Unless very carefully formulated, monobaths have a strong tendency to fix out lower densities. In other words, monobaths would cut film speed drastically by fixing out the shadows before they could be developed.^{footnote 3}

Since the first redeveloper described earlier has already developed Zones I through III, the only lower densities a monobath can fix out of a contraction negative are the midtones. This is exactly what we want. With a specially formulated monobath as a second redeveloper, contrast is reduced (fixed out) in the midtones of a contraction negative. In the higher Zones, contrast is restored and density reduced simultaneously due to the combined action of the developer and thiosulfate, respectively.

This elegant selective redevelopement takes place in only 30 seconds and has no tendency whatsoever to uneven development. It produces a reverse compensating effect, developing a greater percentage of grains in a Zone XII region of the negative than it does in a Zone XI region (etc). The result is a curve much like Figure 1. (NOTE: The problems associated with compensating development mentioned in "Zone System Contraction — A New Theoretical Approach", do not apply to negatives that have already been developed and bleached. For more information about compensating developers refer to that article).

Starting with a developed, fixed, washed, and dried negative. The Monobath Method steps, all done in room light, are:

1. Bleach
2. Rinse
3. First Redeveloper
4. Rinse
5. Second Redeveloper
6. Stop, Fix, Wash, and Dry

I do all my Monobath Method reprocessing steps in trays (5x7 for 4x5 negatives), one negative at a time. Using tanks or reels, or processing more than one negative at a time will prove disastrous. Negatives intended for Monobath Method redevelopement must not have fingerprints or be carelessly washed. Handle these negatives with care.

Chemicals and Bleaching

I find that keeping the Monobath Method stock solutions (percent) listed in Table I are a great asset. As a reminder, a 10-percent solution is made by dissolving 10 grams of a chemical in 1 liter of water.

I use an ordinary potassium ferricyanide and potassium bromide bleach (see Table II). Use it until it’s exhausted, which for me is after about a dozen uses. Simply insert the well washed negative—wet or dry—emulsion side up in the bleach tray. Bleaching is always carried to completion. If you are in a hurry, agitate constantly. If you aren’t, occasional agitation is adequate. Bleach time is approximately 2 to 5 minutes.

Bleaching is not complete until, upon turning the negative emulsion side down in the tray, you can see that all traces of blackened silver have disappeared. You can still see the image after bleaching, but it will be very transparent and, in the case of T-Max films, will have a decided magenta color. Wash the negative with constant agitation in running water for 2 minutes.

Redevelopement

My first redeveloper is a variation on the old Beutler Acutance formula. Do no exhaust this developer. I recommend reprocessing no more than three medium-format negatives (or two 4x5’s) in 250ml of first developer. I’ve provided two first redeveloper formulas (Table III). The formulas vary only in concentration (activity), and one of them is almost certain to produce the desired results. Immediately before use, ad 3 to 6 drops of Kodak Photo-Flo 200 for each 250ml redeveloper. Redeveloper temperature should be carefully maintained at 20°C. To find out which of the redeveloper formulas works for you (and your correct redevelopement time) you’ll have to run a couple of tests.

The ideal redeveloper time is the absolute minimum time that produces complete, or near complete, redevelopement of Zones I to III. For testing, expose eight negatives to Zones I through VIII, process normally, wash, dry, and record their densities. Bleach the negatives, and redevelop in either “A” or “B” for 3 to 5 minutes. Fix, wash, and dry the negatives.

Now read the densities, again. Zones I through III should have the same (or similar) densities you recorded in your first reading. (It is acceptable for Zone III to have slightly less density). Zones IV and up should have considerably diminished density (about 0.55 to 0.65), as the curve flattens out dramatically. If you do not get adequate redevelopement of Zones I through III, expose new film and repeat the test, adding 30 seconds to the redevelopement time for each new trial. If you get adequate redevelopement on the first trial, continue testing, subtracting 30 seconds time for each trial until you get a failed test. Use the shortest time that gave you successful results.

In testing redeveloper “A”, if you find that your redevelopement time is longer than 5 minutes, rebleach and repeat the test with redeveloper “B.” If you test “B” and your redevelopement time is less than 3 minutes, switch to redeveloper “A.”

Once you’ve determined your minimum first redevelopement time, you probably need never run this test again. However, it’s always wise to run tests periodically, just to make sure that nothing has changed.

The first redeveloper is the only stage in the process where uneven development is possible. If you are a moderately careful worker, it is very unlikely. Here’s what to do.

I set my clock for the minimum redevelopement time and insert the negative emulsion side up. I immediately rock (no shaking) the tray vigorously for the first 10 seconds, then repeatedly turn the negative face up and face down, until elapsed time is 30 seconds. At 30 seconds, I leave the negative resting face up under the solution and don’t disturb it until 2 minutes have passed. At the 2 minute mark, I agitate the tray for 5 seconds or turn the negative face up and face down three times. I don’t disturb the tray again until redevelopement is complete. If redevelopement time is more than 4 minutes, I agitate again at the 4 minute mark. The secret to the first redeveloper, and its required compensating effect, is minimum agitation and long periods of undisturbed development.

Watch your negative while it’s redeveloping. If significant unevenness occurs, and has not evened out by the 2 minute mark, rinse the negative thoroughly, bleach, and start over. You haven’t ruined the negative.

If uneven redevelopment persists even with careful work, it’s possible the negative was inadequately washed, has fingerprints or some other surface defect. Select another negative.

After the first redeveloper, thoroughly rinse the negative. It can then be held indefinitely in a tray of water.

Second Redeveloper Procedure

The second redeveloper (monobath) can be used at 20°C ± 2°C. I first rock my monobath tray vigorously for 5 seconds, then insert the negative emulsion side up and continue rocking to the 60-second mark. Redevelopement is complete in 30 seconds. The extra 30 seconds is a safety margin. Do not leave the negative in the monobath longer than 60 seconds.

Each monobath batch (250ml) can be used for only two negatives of any size and then must be discarded. If your trays allow you to fully immerse a negative in 125ml of solution, feel free to cut the formulas in half. However, don’t try this with the first redeveloper.

As you’ll see later, modifying your monobath may quickly exceed the 250ml starting volume. Don’t worry about too much volume; it’s too little volume that causes problems.

After the monobath, immediately immerse the negative in an ordinary acid stop bath for one minute, then fix (I use an acid hardening fixer for two minutes), wash, and dry normally. You’re now ready to print.

Monobath Options

I’ve provided two starting monobath formulas in Table III. Monobath 1 contains both hydroquinone and metol, and tends to emphasize highlight contrast. Monobath 2, containing metol only, provides somewhat greater contraction and gives slightly greater midtone contrast. The differences in performance between the two monobaths are slight.

As a starting point, you can expect either of the monobaths to remove about 0.4 to 0.6 density units from your negative‘s greatest pre-bleach density, depending largely on the extent of your first redevelopement. This is roughly an N-2 to N-3 contraction, but don’t take that very seriously.^{footnote 4} Always print the negative to see what you’ve really got.

To get less contraction, decrease thiosulfate in either monobath in 5g increments. No other changes should be necessary for achieving less contraction to the degree desired. If necessary, increasing developer and sodium hydroxide content would do the trick.

To get greater contraction, you can make any one, or a combination of the following changes in your monobath formula for the next negative:

1. Increase thiosulfate content in 10g to 20g increments to a 200g maximum.
2. Add ammonium chloride in 2g to 4g increments to a maximum not exceeding 20-percent of the thiosulfate.
3. Decrease hydroquinone in Monobath 1 in 0.5g to 1g increments to a 1g minimum.
4. Decrease Metol in Monobath 2 in 0.5g increments to a 0.5g minimum.
5. Decrease sodium hydroxide in either monobath in 1g increments to a 1g minimum.

You can get small contraction increases by changing only one aspect of the formula at a time, but some formula variations produce slightly different effects. Increasing the fixer activity reduces midtone contrast. Alternately, reducing either the developing agent or sodium hydroxide tend to slightly reduce highlight contrast.

For large increases in contraction, I advise simultaneously increasing fixer activity, and reducing developer and sodium hydroxide content. I prefer this to adding large amounts of thiosulfate.

A very powerful way to increase fixer activity is to add ammonium chloride solution (Table I) to either monobath. This combines with the thiosulfate ions and produces some ammonium thiosulfate (rapid-fix) dramatically increasing the monobath‘s fixer activity, and producing greater contraction. Start by adding 2 grams (10ml of percent solution) ammonium chloride to either formula as the last ingredient. As more contraction is needed, increase ammonium chloride content in 2 to 4 gram increments. Adding ammonium chloride produces an ammoniacal odor, so don’t skimp on the ventilation.

You’ll reach maximum fixing speed when the ammonium chloride equals one-fifth the sodium thiosulfate content. If you still need more contraction (more fixation), increase both the sodium thiosulfate and ammonium chloride content in a parallel fashion. Don’t get carried away. Very high fixer activity may fix out the entire negative before the developer can go to work.

After each contraction, record the formula(s) used, first redeveloper time, and the pre- and post-contraction maximum densities for the negative. This information will be a great help with future contraction negatives.

I’ve found I can almost alway get within 0.2 density units (about one Zone for me) of my target on the first try. This leaves most of my duplicate negatives available for experimentation. Always save your best negative for last.

Discussion

There are no specific formulas for N-3, N-4, etc., contraction with this method. Not only is such an approach unnecessary, it would actually be counterproductive in light of the extreme versatility of the Monobath Method. Each negative is different and you will have specific ideas for the kind of tonal relationships you want that can and will significantly change the required formula.

For example, you can achieve N-3 in several different ways, depending on the kind of characteristic curve you want. If you want a negative that emphasizes contrast in the midtones and lets the highlights go flat (the same effect as the old compensating developers) simply extend first redeveloper time (about 7 to 12 minutes), and fix the negative, skipping the monobath. This is actually an old approach called harmonizing.

If you wish to emphasize highlights and sacrifice midtones you can give the minimum first redevelopement time, and use a monobath of moderate to high fixer strength as a second redeveloper. If you want something between the two extremes, you can slightly extend first redeveloper time, and use a monobath with higher fixer content and/or activity.

The amount of variation is virtually limitless, so I highly recommend experimenting with this system for a few days using unimportant negatives. Start with N-2, N-3, and N-4 Contractions.

If you own one, take densitometer readings from each negative before and after using the Monobath Method. Before making any changes to the formulas, print the negatives. The negative densities will tell you if your monobath formula is correct for the desired degree of contraction. The test prints will tell you which grade of paper you should gear the negative toward, and whether or not the negative actually prints well.

A densitometer helps, but is not necessary to the application of the Monobath Method. You can quickly learn to judge densities visually by using a Kodak (or other brand) step tablet.

With my diffusion enlarger, I target my contraction negatives to a grade 3 paper. I rarely go to a lower paper contrast, but will often go up to grade 4.

You must give up something with any contraction negative. When you give up midtones, expect them to look dark in the test print. Don’t incorrectly assume you’ve lost film speed. If the midtones are too dark in your test print, give your next negative more time in the first redeveloper, and use a monobath with a much greater fixing power.

If you give a negative extensive contraction (roughly N-5 to N-10), don’t expect the highlights to be sparklingly crisp. (For a technique that retains full highlight contrast, regardless of the degree of contraction, see "The Highlight Contraction Method." The Monobath Method works beautifully, but it’s not magic. As developer activity decreases, the film’s flattened mid-section, reaches further and further to the right, including more and more of the highlights. The Monobath Method is not perfect, but will give you an extreme contraction negative with fine grain, high acutance, very even development, and full film speed. Not a bad trade-off.

One last thing. Thus far, I have found no limits to the Monobath Method. However, if you should find a situation where you cannot devise a formula that gives sufficient contraction, I’ll leave you with six words that can solve the problem:

The Whole Process Can Be Repeated!

Table I. Percent Solutions
1 liter	20% Sodium Sulfite (anhydrous)
1 liter OR	20% Sodium Carbonate (anhydrous) 25% Sodium Carbonate (monohydrated)
1 liter	4% Metol
1 liter	4% Hydroquinone*
1 liter	25% Sodium Hydroxide
1 liter	50% Sodium Thiosulfate
1 liter	20% Ammonium Chloride**
* Before dissolving Metol or Hydroquinone, dissolve an equivalent amount by weight of Sodium Sulfite as a preservative. Store these solutions in dark brown glass bottles. ** Otional solution. See text. Note: Dissolve all chemicals in 52°C water and let cool to room temperature (19–21°C) before use.

Table II. Bleach
Water (room temperature)	400 ml
Potassium Ferricyanide	11 g
Potassium Bromide	12.5 g
Water to make	500 ml

Table III. First Redevelopers
Redeveloper A
Water at 20°C	750 ml
Metol	0.5 g
Sodium Sulfite	2.5 g
Sodium Carbonate (anhydrous)	2.5 g
Water to make	1 liter
Redeveloper B
Water at 20°C	750 ml
Metol	1 g
Sodium Sulfite	5 g
Sodium Carbonate (anhydrous)	5 g
Water to make	1 liter

Table IV. Starting Monobath Formulas
Monobath I
Sodium Sulfite	6 g (30ml of % solution*)
Hydroquinone	3 g (75ml of % solution*)
Metol	0.125 g (3ml of % solution*)
Sodium Thiosulfate	40 g (80ml of % solution*)
Sodium Hydroxide	5 g (20ml of % solution*)
Water to make	250ml
Monobath II
Sodium Sulfite	6 g (30ml of % solution*)
Metol	2 g (50ml of % solution*)
Sodium Thiosulfate	40 g (80ml of % solution*)
Sodium Hydroxide	5 g (20ml of % solution*)
Water to make	250ml
* See Table 1.