They depend on the reversible colour change of pigment materials encapsulated in a translucent foil / carrier material. The CelsiReverso® are not LC (liquid crystal) based indicators.
PRINCIPLE OF OPERATION
The basic function of the ThermoDot®s and Thermoband®s depend on the reversible colour change of pigment materials encapsulated in a neutral and translucent carrier material. This is not a chemical reaction to translate the temperature level(s) into visible form. There are temperature indicators on the market whose indications are based on chemical reactions of the indicating materials used. Such chemical reactions depend obviously on both the temperature AND the exposure time.