A package of thermographic or photothermographic materials has a primary packaging enclosure, and optionally a secondary packaging enclosure, containing one or more of the materials (such as individual sheets). A non-photosensitive indicator device is associated with either or both of the packaging enclosures. This non-photosensitive indicator device is adapted to provide a visually observable indication of a predetermined cumulative thermal exposure and a predetermined temperature event (that is, single temperature event) of the package. This indicator device is able to provide information as to the time-temperature history of the package.