How They Work

As implied in the name reversible temperature labels can change color back and forth as needed in order to and display the current temperature in which they are exposed. One advantage of reversible labels is that they can be used multiple times. Since they are constantly changing depending on the temperature they are in monitoring of them must be done at the time of the event. They will not record temperature changes from the past only display the current temperature.

The molecules in the liquid crystal thermometer are made of cholesterol, and are called cholesteric liquid crystals. The molecules are rod-shaped. The labels show colors by selectively reflecting incident white light. Conventional temperature-sensitive mixtures, in thin films, reflect bright, almost pure colors, turning from colorless ( black, against a black background ) to red at a formulated temperature and, as the temperature is increased, pass through the other colors of the visible spectrum in sequence ( orange, yellow, green, blue and violent ) before turning colorless (black) again at a higher temperature still. The color changes are reversible and on cooling the color change sequence is reversed. PLEASE NOTE: Exposing temperature labels above 250°F / 122°C for extended periods will damage and/or destroy the liquid crystals.