As soon as a light-sensitive material is developed, it contains a visible silver image, but the image is not ready to be exposed to light. Only a portion of the silver halides in the emulsion were reduced to black metallic silver by the developer. The silver halides that were not reduced restrict both the immediate usefulness and the permanence of the image. These undeveloped silver halides must be removed. This is the purpose of the fixing bath. Before treating the sensitized material in the fixer (as it is called), you must stop or at least slow down the action of the developer. When the light-sensitive material is removed from the developer solution, there is a small amount of developer both in the emulsion and on the surface that must be removed or neutralized. For this, you use either a water rinse bath or an acid stop bath.

WATER RINSE BATH

To slow down the action of development, you must immerse the film in a water rinse bath. A plain water rinse bath is commonly used between development and fixation to slow down the development by removing all the developer that is clinging to the film (or paper) surface. A rinse bath does not completely stop development but retards it. A rinse bath has little affect on the developer that is actually in the swollen emulsion.

Rinsing is accomplished by quickly immersing the film in plain, clean water. A water rinse bath should be changed often to ensure it does not become loaded with developer. It is better to use running water.

The rinse bath, then, serves two purposes: first, it slows down development and second, it reduces the work that has to be done by the acid in the fixer. Rinsing, therefore, protects or prolongs the useful life of the fixer.

Following rinsing in plain water, the material (that is still light sensitive) must be treated in an acid fixing bath to stop the development.