Metol(Elon) Developing Agent is used as a developing agent, usually with hydroquinone, but sometimes by itself as in Kodak D-23.
- Although metol is easily soluble in water, it is not soluble in a strong sodium sulfite-solution. It does dissolve readily in a weak solution of sulfite. Metol bulds image detail rapidly, and it keeps well in solution.
- Metol has low-fogging tendencies and responds well to the addition of bromide, giving a very clean-working developer without any staining of film or fingers.
- The energy of the developer is only slightly affected by low temperature and is only slightly reduced by the addition of bromide.
- Metol alone with either sodium or potassium carbonates give a rapid working developer when the alkalies are in high concentration, but the speed of the development can easily be controlled by dilution.
- The use of caustic alkali (e.g., sodium hydroxide) is not recommended with metol as there is a tendency to excessive fog. When used with sulfite alone, without additional alkali (Kodak D-230, metol provides a slow-working, fine-grain developer. This type of film developer often works well with a mild alkali, such as borax, which accelerates the rate of development without increasing the grain size appreciably (Kodak D-25).
- Developers containing metol as the sole developing agent are not widely used but metol with hydroquinone provides the most widely used developer combination.