• Commercial film developing utilizes a number of chemicals.film image by saied shahinkiya from Fotolia.com
  
  When you take a photograph, the light that penetrates the shutter and shines onto the film reacts with the chemicals or metals of the film. To view the photo, you must have the film developed in order to see the reaction. The entire process takes place in one machine without human interference during the commercial film-developing process, unlike personal darkroom processes.
  
  

Developer

• Black and white developer can be made from aminophenol, borax, catechin, chlorquinol, diaminophenol hydrochloride, glycin, hydroquinone, monomethyl p-aminophenol sulfate, phenidone, p-phenylene diamine, potassium bromide, pyrogallic acid, sodium formaldehyde bisulfate, or sodium hydroxide. For color film, potassium thiocyanate, monoethanolamine, ethylene diamine, ethoxydiglycol or diethanolamine are used. The chemicals are toxic and should be handled with care. They develop the image on the film, whether it is silver halide from black and white film, or the silver, nitric acid and gelatin on color film.
  
  

Stop Bath

• The stop bath includes a mixture of one part acetic acid and 30 parts water. The stop bath is highly toxic. It is corrosive, causes burns on the skin and can be fatal. The stop bath stops the developer from continuing to turn the silver halide or color film silver, nitric acid and gelatin. It is only a temporary stop, however, because light can still affect the image on the film. Fixer is needed to stop the development process entirely.
  
  

Fixer

• Sodium thiosulfate and sodium bisulfite are the two chemicals used in fixers for commercial film development. The unexposed and undeveloped chemicals and metal on the film are dissolved and removed during this process. This ensures that the film is not changed later, ensuring the photo will always be the same when it is developed from this film. Fixer chemicals are also toxic.