Kehitysnesteet

Kehitysnesteet, known in English as developing solutions, are chemical solutions used in the photographic process. Specifically, they are employed in the development of latent images formed on photographic film or paper after exposure to light. The primary function of a developing solution is to convert the exposed silver halide crystals, which have undergone a photochemical change, into visible metallic silver.

The exact composition of developing solutions varies depending on the type of photographic material and the desired outcome. However, common active ingredients include developing agents, such as hydroquinone or phenidone, which are reducing agents. They also typically contain an alkali, like sodium carbonate or sodium hydroxide, to increase the pH and accelerate the development process. Other components may include preservatives to prevent oxidation of the developing agents and restrainers to control the rate of development and reduce fogging.

The process of development involves immersing the exposed photographic material in the developing solution for a specific period. During this time, the developing agent selectively reduces the exposed silver halide crystals to metallic silver, forming the visible image. Unexposed silver halide crystals are generally unaffected by the developing solution. Once development is complete, the film or paper is moved to a stop bath to halt the development process, followed by a fixer to remove the remaining unexposed silver halide and make the image permanent.