Abstract: A container closure integrity indicator having a first component comprised of a sheet of absorbent material permeated with an indicator dye in solution with a volatile solvent, and a second component comprised of a sheet of absorbent material permeated with a volatile activator solution, with preferably has a pH outside of the range of 5-7. The two components initially are sealed together, between a closed container surface and a superposed transparent cap member, so that the resulting liquid phase defined by the components characterized by a color, which is a function of any change to the liquid phase pH with respect to the relative amounts of dye, volatile solvent solution, and volatile activator solution.