Scientific calculator. Candy Experiments: Experiments. Royal Society of Chemistry | Advancing the Chemical Sciences. Photographic fixer. Fixer is used for processing all commonly used films, including black-and-white films, Kodachrome, and chromogenic films. In chromogenic films, the remaining silver must be removed by a chemical called a bleach fix, sometimes shortened to blix. This contains a mixture of ammonium thiosulphate and ferrous EDTA, a powerful chelating agent. Jump up ^ Sowerby, A.L.M. (ed.) (1961). Stop bath. Stop bath is a chemical bath usually used in processing traditional black-and-white photographic films, plates, and paper used after the material has finished developing. The purpose of the stop bath is to halt the development of the film, plate, or paper by either washing off the developing chemical or neutralizing it.
With the former, a simple water rinse can be used between developer and fixer, but the development process continues (though possibly at a very low level) for an indefinite and uncontrolled period of time during the rinsing. Where an immediate stop of development is desired, a stop bath will usually consist of some concentration of acetic acid, commonly around 1 to 2%. Since organic developers only work in alkaline solutions, stop bath halts the development process almost instantly and thus provides more precise control of the development time. Stop bath accounts for the characteristic vinegar-like odor of the traditional darkroom. Photographic developer. In the processing of photographic films, plates or papers, the photographic developer (or just developer) is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatine matrix.
As a generalisation, the longer a developer is allowed to work, the greater the degree of reduction of the silver halide crystals to silver and therefore the darker the image. History[edit] Formula[edit] For black-and-white photography, the developer is typically a mixture of metol (monomethyl-p-aminophenol hemisulfate), phenidone (1-phenyl-3-pyrazolidinone) or dimezone (4,4-dimethyl-1-phenylpyrazolidin-3-one) and hydroquinone[1] (benzene-1,4-diol). Most developers also contain small amounts of potassium bromide to modify and restrain the action of the developer[2] to suppress chemical fogging. Development[edit] Colour development[edit] Reversal film development[edit] Proprietary methods[edit]