Thermal gel - color changes due to temperature changes Extravagant and absolutely trendy !!! The color changes in our thermochromic color gels are caused by temperature changes. The coloring substances used consist of microcapsules which change the color reversibly. As soon as a temperature of 30-31 ° C is reached, the colors change into different shades and return to their original color when the temperature falls. This is a very extravagant development and is absolutely trendy.