What is a characteristic of thermochromic pigments?

Thermochromic pigments are materials that exhibit a change in color in response to variations in temperature. This characteristic allows them to be used creatively in various applications, from product design to special effects in certain environments. The change in color occurs as a result of the phase transition of the pigment, which can alter the way it absorbs and reflects light based on temperature changes.

In contrast, the other options do not accurately describe the properties of thermochromic pigments. For instance, if pigments were to permanently change color without temperature influence, they would not be classified as thermochromic. Similarly, while thermochromic pigments can be used in textiles, their applications extend far beyond that specific material, encompassing inks, ceramics, and other products. Lastly, thermochromic pigments can indeed be combined with polymers, allowing for innovative uses in a variety of plastic products, enhancing their functionality and appeal. Thus, the defining trait of thermochromic pigments is their ability to change color in response to heat.