A thermally responsive ink composition consisting of at least one halochromic optical-state change material, at least one base, at least one solvent, and at least one binder material. The pH of the ink composition is such that the halochromic optical-state change material remains in its basic state until it is acted upon by a thermal stimulus. The ink composition is capable of transforming from a first optical state to a second optical state upon a change in pH caused by exposure to a thermal stimulus. A thermally responsive ink composition consisting of at least one quaternary onium salt of an halochromic optical-state change material, at least one solvent, and at least one binder material is also disclosed. Coating compositions prepared using these ink compositions and optical articles comprising these coating compositions are also disclosed.