Ilford Ilfostop is a low odor acid stop bath. Normally, when development is completed, films and papers are subjected to a stop bath rinse. This immediately halts the developing process by neutralizing the developer.
Ilfostop contains an indicator dye that is pH sensitive and changes color from yellow to purple as the stop bath becomes exhausted. It is specifically recommended for dish and tray processing of paper or deep tank processing of film.
It should be noted that Ilford recommends that gloves, eye protection, apron or overall be worn when handling and mixing all chemicals.