De data asta din „The Film Developing Cookbook“, p.83 (ISBN 0240802772):

Two bath developers give excellent results with almost all films at a fixed time and temperature. It is almost imposible to overdevelop with two bath, and it takes an effort to underdevelop [no, it doesn’t. It was very easy, just look at the pic bellow—n.m.]. There are ideal for photographers who want quality negatives but are not interested in obsessing about developers.

Although Zone-style control is not possible with two-bath, this is not a real limitation with thin emulsion films.

In two-bath developers the A bath contains the developing agent with no alkali, so that minimal development takes place. The film is immersed in this solution only to absorb the developing agent.

The B bath contains the alkali activator. In the B bath the developer is quickly exhausted in the highlights, making overdevelopment difficult. This also improves shadow contrast and increase definition. Agitation may be continuous without impairing image quality, ensuring even development with no streaking, mottling, or air bubbles. Two-bath are thus a tenable choice for JOBO rotary processors. However, it is exceedingly important to break up the directional flow during agitation, particularly during continuous agitation.

Two-bath can be used for virtually all films except document films. Since time is fixed, development is automatic, resulting in:

• normal emulsion speed, or slightly higher
• good acutance with moderately fine grain
• long scale gradation, with some highlight compensation, allowing high contrast scenes to be photographed without special adjustments
• good economy

The stock solutions of most two-bath will keep for six months in tightly sealed bottles. Solution A can be used for up to 20 films. The inexpensive, replaceable Solution B should only be used for ten rolls of film. After ten rolls, discard and make fresh solution. Unlike reused or replenished single bath developers, there is almost no compromise in quality when the two-bath is reused.

Although two-bath developers are not ideal for very low contrast scenes, moderately low contrast scenes can be printed on a high grade of paper. In any case, extended development, which was routine in the early days of the Zone Systems, fails with modern films. Today, expansion (i.e. high contrast) is best obtained by using a special high contrast developer.

Underexposed, underdeveloped

Solution A
Sodium Sulfite, 35 grams
Hydroquinone, 6 grams
Phenidone, 0.2 grams
Sodium Bisulfite, 6 grams
Water to make, 1 liter

Solution B
Sodium Sulfite, 65 grams
Sodium Metaborate, 20 grams
OR
Borax 20 grams (for results „like that of D76“)
Water to make, 1 liter

De reținut: nu ud filmu înainte, chit că mi se înverzește soluția A. E ok să bîltîcîi filmul în a doua soluție, chiar și întruna dacă așa am chef.