Photographic fixer

Photographic fixer

Photographic fixer is a chemical used in the final step in the photographic processing of film or paper. The fixer removes the unexposed silver halide remaining on the negative or photographic paper, leaving behind the reduced metallic silver that forms the image. By removing the unexposed silver halide, the fixer prevents any further reaction of the silver salts and ensures a permanent image. If the film or paper was not fixed, the remaining silver halide would quickly darken and cause severe fogging of the image. The film or paper can be exposed to light after fixing.

Fixer is used for processing all commonly used films, including black and white films, color negative films (C41), color reversal films (E6), and chromogenic films.

Most fixers are based on the thiosulfate ion, especially ammonium thiosulfate. Up until the 1970s, sodium thiosulfate 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.

In the case of chromogenic (color) films, the elemental silver left behind after development must be subsequently removed by solution in a chemical cocktail called a bleach fix or blix. This contains a mixture of ammonium thiosulfate and ferrous EDTA, a powerful chelating agent.


One disadvantage of the use of thiosulfate 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 photographic 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 (resin) coated papers, washing for as little as 2 minutes in warm water can be sufficient to eliminate residual fixer. Washing aids (also called hypo clearing agents) can be used to make the process of removing fixer faster and more thorough.

A quick, water-saving, and archival technique for washing film fixed "with nonhardening fixer" in a spiral tank is the popular "Ilford method" [Ilford Rapid Fixer Fact Sheet, August 2002] :

* Fill the developing tank with tap water at the same temperature as the fixer (+/-5 ºC or 9ºF)—maintaining a constant bath temperature during processing is necessary to avoid reticulation of the emulsion;
* Invert the tank five times and drain it completely;
* Fill the tank again, invert it ten times, and drain it completely;
* Fill the tank again, invert it twenty times, and drain it completely.
* The film is now washed.

More conventional darkroom practice recommends washing film for 30 minutes or longer, with a flow of water sufficient to change the water in the washing container at least three times. This is not needed when nonhardening fixers are used.

Overwashing can actually reduce the archival properties of film, as thiosulfate in very small concentrations has been shown to have a beneficial effect on film image stability. [ [ Washing - Silvergrain Labs ] ]


ee also

* Film developing

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • photographic fixer — fotografinis fiksažas statusas T sritis fizika atitikmenys: angl. photographic fixer vok. photographisches Fixierbad, n rus. фотографический фиксаж, m pranc. fixateur photographique, m …   Fizikos terminų žodynas

  • Fixer — may refer to:pecialist usesBetting*A person who uses various techniques to alter the course of a sports game for the benefit of a particular betting party. For example, a boxer who purposefully loses a match or a basketball player (see Ralph… …   Wikipedia

  • Photographic processing — is the chemical means by which photographic film and paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders… …   Wikipedia

  • Photographic emulsion — is a layer of light sensitive material coated onto a substrate. In Silver gelatin photography, the emulsion consists of silver halide crystals suspended in gelatin, and the substrate may be glass, plastic film, paper or fabric. In proper chemical …   Wikipedia

  • 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… …   Wikipedia

  • Photographic Alliance of Great Britain — The Photographic Alliance of Great Britain (known as the PAGB) is the umbrella organisation that provides benefits and co ordinates specific events for the majority of photographic clubs and societies in England, Scotland, Wales Northern… …   Wikipedia

  • Photographic filter — Four photographic filters. Clockwise, from top left, an infrared hot mirror filter, a polarising filter, and a UV filter. The larger filter is a polariser for Cokin style filter mounts. In photography and videography, a filter is a camera… …   Wikipedia

  • fixer — noun a) Agent noun of fix; one who, or that which, fixes. b) A chemical used in photographic development that fixes the image in place, preventing further chemical reactions. See Also: the fix is in …   Wiktionary

  • fixer — /ˈfɪksə/ (say fiksuh) noun 1. Photography a chemical solution used to remove the light sensitive silver halides from the photographic image, rendering it permanent. 2. a mason who sets stones in walls. 3. someone who finds solutions in difficult… …   Australian English dictionary

  • fixer — n. 1 a person or thing that fixes. 2 Photog. a substance used for fixing a photographic image etc. 3 colloq. a person who makes arrangements, esp. of an illicit kind …   Useful english dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.