What they are:
These self-adhesive labels consist of a series of temperature sensitive elements containing microencapsulated Thermochromic Liquid Crystal, TLC, coated on a black backing. Each element changes color distinctly as its rated temperature is reached.
Digi-Temp® color changes are reversible passing through the colors of the spectrum in sequence (Orange, Yellow, Green, and Blue before turning black at a higher temperature. The TLC strips are calibrated so that the indicator that shows green indicates the actual temperature. The color changes are reversible and the reflected colors will be observed in the reverse order upon cooling.
Digi-Temp EZ single color changes are reversible meaning that the attained and maintained reflected color will turn black as the temperature is reversed. Thermochromic Single Color Change (EZ) Labels can be ascending or descending, that is, change from black to a color as temperature increases or black to a color as the temperature decreases
How they work:
The temperature-sensitive elements contain TLC molecules that are very sensitive to temperature and change their arrangement in response to changes in temperature. This change in molecular geometry affects the way in which the TLC interacts with light, resulting in a change in the color of each temperature event. When the rated temperature of an indicator is reached, the TLC changes its form from reflecting (color) to non-reflecting (black) or vice versa. This causes the color-change at the temperature event to occur.