ILFORD ILFOSTOP is a low odour citric acid stop bath. After development we recommend that films and papers are rinsed in an acid stop bath to stop development immediately and neutralise the developer to help maintain the activity of the fixer bath.
ILFOSTOP contains an indicator dye that is pH sensitive and changes colour from yellow to purple as the stop bath becomes exhausted. It is specifically recommended for dish/tray processing of paper or deep tank processing of film. ILFOSTOP helps to maintain the activity and prolong the life of the fixer solution by reducing carry over of excess developer (alkaline) into the fixer bath (acidic). It is not recommended for machine processing applications as the short fix and wash times often used may leave a residual dye stain on films and prints. The longer wash times usually associated with dish/tray and tank processing minimise this risk.
Do not let developer become contaminated with a stop bath solution.