A negative developer of maximum energy and highest contrast. In these properties it yields far more than the undiluted solution according to formula, but it possesses the disadvantage of not keeping well once it is mixed. This formula is of good service in all cases where high speed is of importance (press photography) or maximum contrast (process work, X-ray films, etc.).

Solution A
IngredientQuantity
Hydroquinone32grams
Sodium sulphite anhydrous25grams
Phenosafranine 1:1000 solution5mililiters
Potassium bromide0.5grams
Water to make0.5liters
Solution B
IngredientQuantity
Potassium hydroxide50grams
Sodium sulphite anhydrous25grams
Potassium bromide0.5grams
Water to make0.5liters

Making up: To make the phenosafranine stock solution, dissolve 1 gram of dyestuff in 1 liter of warm water, and stir or shake thoroughly. To make Solution A, dissolve the chemicals in the larger quantity of water, in the order given, and after all chemicals have dissolved thoroughly, fill up with cold water to the full volume. With this formula as well, it is advisable to add a pinch of sulphite to the water, before dissolving the hydroquinone. When making up Solution B, it should be remembered that potassium hydroxide is a caustic, and should on no account come in contact with the skin. When handling hydroxide in sticks, protect the fingers with a piece of paper, but it is better to use this chemical in flake or pellet form. It should be weighed quickly, since it easily absorbs moisture from the air; on this account it must be stored in a rubber-stoppered bottle. When dissolving hydroxide in water a considerable amount of heat is evolved, so that only cold water should be used for this purpose. The storage bottle for Solution B should have a rubber stopper, since the chemical attacks cork, and glass stoppers often remain firm in the neck of the bottle.

Dilution and times of development:

  1. For high-speed development, mix Solutions A and B in equal proportions. This developer also has the quality of bringing out the weakest detail in the shadows; it is thus suitable for negatives that have been under-exposed. Develop for 20–30 seconds.
  2. For maximum contrast, increase the quantity of potassium bromide in Solution A to 20 grams, and mix as follows: 1 part A, 1 part B, and 2 parts of water. Develop for 2.5–3 minutes.

Keeping qualities and use: Stock Solutions A and B have unlimited keeping qualities, but when combined deteriorate rapidly. The mixed solution, however, can be used a number of times in succession.

An economical way of using this formula is the two-bath method, whereby each solution is employed separately as follows:

  • High-Speed Development: Immerse the film in Solution A for 15–20 seconds, and then without intermediate washing, transfer to Solution B for about 10 seconds, or until there is no further perceptible growth in image.
  • Contrast Development: Increase the quantity of potassium bromide for Solution A in accordance with the instructions given hitherto. The film is then immersed in Solution A for 2 minutes, and in Solution B for 1 minute.

With the two-bath method, no development whatever takes place in Solution A, and it is essentially a matter of the emulsion becoming fully saturated with solution during this stage. Solution A, therefore, is never chemically exhausted, and may be used to the last drop. The two-bath method is an economical one for B, although transferred developer causes Solution B to discolour, and the solution must be discarded when it assumes a strong brown colour. It is still more economical to use in this way, than mixed with Solution A.

Remarks: As the Solution B is caustic, do not dip bare fingers in the developer; use plate-holders or rubber fingerstalls. Desensitizers are useful with high-speed formulæ containing a relatively small quantity of bromide, because of their anti-fogging properties. If 0.2 grams are combined with Solution A, no influence on development speed is observed, but the danger of fogging is eliminated.