Developers for Contrast Control

The developers mentioned so far are used in general photography of subjects in reasonable lighting and with a normal distribution of tones. There are other forms of photography for which it may be desirable to use developers that produce low-contrast or high-contrast images. Specialized graphic-arts work is an obvious application for high contrast. Frequently, high-contrast films are used and the developer is required to produce only one tone and maximum black. The soft-working developers already mentioned generally use metal as the developing agent and a mild alkali. For more energetic working, hydroquinone is preferred with sodium carbonate or hydroxide as the strong alkali content. Very-high-contrast materials require developers based on hydroquinone and sodium hydroxide. These solutions do not keep very well and are generally made up in two parts. Designed for process materials, the ID13 developer is composed of equal parts of solutions A and B, mixed immediately before use and then discarded. The development times at 20° Care 2-3 minutes. The opposite requirement for low contrast, occasionally arises for inherently contra sty subjects in brilliant lighting. A popular formulation for that purpose is a simple metal-sulphite type (example: Agfa 14). Their development times at 20° Care 10-20 minutes, according to film speed and contrast required. The high-contrast and low-contrast developers are now used for specialized applications and by a few enthusiastic perfectionists.