What is the chemistry behind thermochromic ink that can be found on coors light cans and clothing?

Patrick K: What is the chemistry behind thermochromic ink that can be found on coors light cans and clothing?
I would like to know about the chemistry side of it like a reaction or mechanism and any other interesting information.

Answers and Views:

Answer by Colin
Basically these are simply chemicals that are different colours at different temperatures. Common Zinc Oxide is white when cold, yellow when hot and this has been known since early chemistry and even in the 1960’s paints were used to show factory pipes that were hot by colour change.

Thermochromic inks or dyes are temperature sensitive compounds that temporarily change color with exposure to heat. They were generally developed in the 1970s. They come in two forms, liquid crystals and leuco dyes.

Liquid crystals are used in mood rings. Leuco dyes are easier to work with and allow for a greater range of applications. These applications include: flat thermometers, battery testers, clothing, and the indicator on bottles of maple syrup that change color when the syrup is warm. The most well-known line of clothing utilizing thermochromics was Hypercolor. The thermometers are often used on the exterior of aquariums, or to obtain a body temperature via the forehead. Coors light uses thermochromic ink on its cans now, changing from white to blue to indicate the can is cold.