Photographic fixer is a chemical used in the final step in the photographic processing of film or paper. Fixer is used for processing all commonly used films, including black and white films, colour negative films (C41), colour reversal films E6, and chromogenic films. C-41 is the name given to the process for developing a specific type of color film used in photography and often to the type of film itself. ... The E-6 process (sometimes abbreviated to just E-6) is a process for developing color reversal (transparency) photographic film. ...

Most fixers are based on the thiosulphate ion, especially ammonium thiosulphate. Up until the 1970s, Sodium thiosulphate or Hypo was the commonly used fixer. Both fixers work best in acid conditions and this is usually created using small quantities of Acetic acid. The fixer removes the unexposed silver halide remaining on the negative or photographic paper leaving behind the reduced metallic silver. By removing the unexposed silver halide, the fixer prevents any further reaction of the silver salts and ensures a permanent image. The negative or paper can be exposed to light after fixing. 1970 was a common year starting on Thursday. ... Sodium thiosulfate pentahydrate Sodium thiosulfate (Na2S2O3) is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3 · 5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo. ... Hypo- a prefix meaning below, low or insufficient. ... The chemical compound acetic acid (from the Latin word acetum, meaning vinegar), systematically called ethanoic acid, is the acid that gives vinegar its sour taste and very pungent smell when at high concentrations. ...

In the case of colour films, the elemental silver left behind after development must be subsequently removed by solution in a chemical cocktail called a Blix or bleach-fix. This contains a mixture of ammonium thiosulphate and Ferrous EDTA, a powerful chelating agent. Hans Blix Hans Blix   listen? (born June 28, 1928 in Uppsala in Sweden) is a Swedish diplomat and politician. ... EDTA is the chemical compound ethylenediaminetetraacetic acid, otherwise known as edetate or versene. ... Chelation (from Greek, claw like) describes the reversible binding of an organic ligand, the chelator or chelating agent, to a metal ion, forming a metal complex, the chelate. ...

One disdvantage of the use of thiosulphate as a fixer is its ability to dissolve elemental silver at a very slow rate. If films or papers are inadequately washed after fixing, any residual fixer can slowly bleach or stain the photgraphic image. For prints on high grade fibre papers, a period of continuous washing in clean, cold water for up to 40 minutes may be required. For modern plastic coated papers, washing for as little as 2 minutes in warm water can be sufficient to eliminate residual fixer. Plastic is a term that covers a range of synthetic or semi-synthetic polymerization products. ...

See Also: film developing A piece of photographic film that has been exposed to light in a controlled manner must be developed before it can be used. ...