Thermochromism

method of digital printing

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.

a ring that contains a thermochromic element,

strip of plastic which changes colour to indicate temperature