Preparing the Processing Solution
Chemicals are now available in liquid concentrates, tailored to the specific type of film being used.
The processing solution can be prepared directly in a tank or in a plastic bucket. In the latter case, each type of solution must be prepared in a separate bucket that must never be used for other chemicals.
Developer
Fog, graininess, and contrast depend on the type of developer and are best prepared based on the film being used.
If using a concentrated manual developer, such as G128 manufactured by Agfa, with a 25-liter developer tank capacity, simply pour 5 liters of concentrated developer into the tank and add 20 liters of water (a ratio of 1 part concentrate to 4 parts water). G128 developer is also used as a replenisher; in this case, add 3 parts water to 1 part concentrate.
Fixer
Fixer is also available in a concentrated liquid form (G328). The same instructions for preparing the developer apply here.
Development Time and Temperature
Depending on the film holder type, the film is clipped onto or slid into the film holder and hung in the developer tank. Once the film is immersed in the developer, the darkroom timer is set to the desired number of minutes. The optimal development time is the time at which the most favorable "contrast fog ratio" is achieved. Slight deviations from the correct exposure time can be compensated by adjusting the development time.
The recommended development time for Agfa film in G128 manual developer is 5 minutes at 20°C. In an automated process using G135 developer, the development time is 100 seconds at 28°C. Deviations from the recommended development time and temperature almost always result in reduced image quality (e.g., increased graininess).