Rapid Fixer is a non-hardening rapid fixer supplied as a liquid concentrate that is diluted with water for use. It is easy and convenient to use in the temperature range of 18-40ºC (66-104ºF) for fixing black and white film and paper in all manual and machine processing applications. The fixing agent in Rapid Fixer is ammonium thiosulphate it contains no sodium thiosulphate (hypo).