Thermochromic color pigments allow for a visual response to changes in temperature. The pigments are composed of microcapsules that change color reversibly. When the temperature is raised to a specified temperature the pigment goes from colored to colorless, colorless to color or from one color to another. Some even have three colors! The color returns to the original color as the pigment is cooled down with the hot pigment or heated up with the cold pigment.