Rapid fixer is a fast-acting photographic fixing solution used to make developed images permanent by dissolving unexposed silver halides from film or paper. It typically contains ammonium thiosulphate or thiocyanate, which accelerates the fixing process compared to standard fixers.
Rapid fixers are particularly useful in darkroom environments where speed is essential, such as high-volume processing labs or when quick turnaround is needed. They ensure that negatives and prints are cleared and stable without prolonged immersion, helping photographers save time while maintaining image quality and archival longevity.