The Ilford Ilfostop Stop Bath 500ML helps in neutralizing the developer after the completion of development process. One another advantage is that it helps in extending the fixer life. Highly recommended for deep tank processing of film or dish and tray processing of paper, the pH sensitive indicator dye present in it changes color from yellow to purple to indicate the draining of the stop bath. With less odor and low acid strength, it is ideal for all practical developing purposes. With 5 years lifetime in full airtight bottles and 12 months in half full tightly capped bottles, it stays fresh for 7 days as working solution.