Used in acid-base titrations to provide a sharp and clear color change at the endpoint. The mixture of bromothymol blue and acid blue 1 gives a distinct color transition, typically from blue to yellow or green to pink, depending on the pH range. This makes it especially useful in titrations involving weak acids and bases where a narrow pH change occurs near the equivalence point. Commonly applied in educational labs, water quality testing, and industrial processes where precise pH indication is needed without using a pH meter.