The irreversible temperature labels are based on a thermosensitive melting wax technology. The technology basically consists of a series of temperature-sensitive elements sealed between heat-resistant layers which, in turn, contain transparent windows to reveal color changes.
Each element changes color when its calibration temperature is exceeded. The changes are irreversible so that they provide a record of the temperature of the surface being monitored. The labels do not deteriorate when removed and can be attached to an inspection report to serve as proof of the temperature reached. They are normally used for industrial applications.
How do irreversible temperature indicators work?
The heat sensitive elements incorporated into these strips are phase change indicators made from organic chemicals whose melting points have been carefully defined to provide unique and highly accurate color changes.
Each temperature uses a different chemical component and, in turn, each component is sealed with a coating that insulates it on a special absorbent paper substrate, usually black in color. When each calibration temperature is exceeded, the chemical in question melts and is absorbed by the substrate, causing the final black color. Up to 10 elements can be combined in a single strip (THERMAX 10 Levels).