thermochromism

thumb|A video showing how to make thermochromatic thermal cards based on Cholesteric liquid crystal|cholesteric liquid crystals Thermochromism is the property of substances to change color due to a change in temperature. A mood ring is an example of this property used in a consumer product, although thermochromism also has more practical uses, such as for baby bottles that change to a different color when cool enough to drink, or kettles that change color when water is at or near boiling point. Thermochromism is one of several types of chromism.

==Organic materials== ===Thermochromatic liquid crystals=== thumb|Demonstration of the phenomenon of discontinuous thermochromism thumb|Demonstration of the phenomenon of continuous thermochromism The two common approaches are based on liquid crystals and leuco dyes. Liquid crystals are used in precision applications, as their responses can be engineered to accurate temperatures, but their color range is limited by their principle of operation. Leuco dyes allow a wider range of colors to be used, but their response temperatures are more difficult to set with accuracy.