There are four main steps in film processing: developing, stopping development, fixing, washing, and drying. To process film in this way, special equipment is necessary, including developing tanks, timers, and photo processing chemicals. Both black and white and color film may be developed manually; the two processes are very similar, though color image processing involves the utilization of different chemicals.
The first step in film processing is the actual development of the film. To begin, a special developing agent is poured into a tank, followed by the submersion of the film in the chemical agent. The agent encourages the release of electrons, which transform the silver halide grains of the film into metallic silver. A thermometer is used during this step to ensure the proper temperature is maintained throughout the process.
The next step in film processing entails stopping the development progression. This ensures that the film does not overdevelop, which jeopardizes the integrity of the captured image by making it too grainy. A chemical mixture known as a stop bath is employed. The film is placed in the stop bath, where it dilutes the developing agent.
The third step in film processing is called fixing. During this procedure, chemicals known as a fixing bath remove the unexposed halide crystals on the film. The chemical solution does not affect the metallic silver; it operates only on the halide and eradicates it from the developing photos.
Submerging the film in clean water further removes all the developing chemicals. This guarantees that no white stains show up on the film negatives. After washing the film in a pan of water for approximately five minutes, the film is hung up to dry.
The drying process generally takes one to two hours. After it has dried, the film can be more easily viewed, and photos can be more easily chosen for enlarging. Once drying is complete and the images have been selected, the negatives are then stored in appropriate packaging, usually clear glassine sleeves or polyvinyl chloride (PVC) envelopes.
Both black and white and color film is developed in this general method. When developing film in color, however, chemicals are used that react differently to the film than their black and white counterparts. As the film processing method progresses, color slowly begins to appear on the film. When it is dry and ready for viewing, the chemicals have prepared the images in color format.