Positive developer. When a brown-tone developer of this type is used, it does not mean that brown tones will be produced on any paper; not all papers are suitable for brown tones. This developer should be used for those papers which are especially designed to produce brown tones, as will be indicated on the label or instruction leaflet.
| Ingredient | Quantity | |
| Mix chemicals in order. | ||
| Hydroquinone | 8 | grams |
| Sodium sulphite anhydrous | 50 | grams |
| Sodium carbonate anhydrous | 30 | grams |
| Potassium bromide | 2 | grams |
| Ammonium bromide | 2 | grams |
| Water to make | 1 | liter |
Before adding the ammonium bromide the solution must be cooled to normal temperature.
Usage: The resultant degree of brown tone is dependent on
- dilution of the developer,
- the degree of over-exposure and
- the time of development.
We may say that the tone becomes warmer as the dilution of the developer is increased, the exposure time lengthened, and the development time prolonged. These operations, however, should not be carried too far, otherwise the gradation will become too soft. The following details will serve as a guide:
- Undiluted: black-brown to sepia.
- 1 part developer to 1 part water: brown.
- 1 part developer to 3–5 parts water: red-brown.
Times of development: For the three concentrations mentioned above, the following developing times are approximately correct:
- 2 minutes.
- 3 minutes.
- 4–5 minutes.
Keeping qualities: The solutions keep well, but in the interests of consistent results do not use until completely exhausted.