The reason why colored yarn changes color when exposed to high temperature

‌The reason why colored yarn changes color when exposed to high temperatures‌ is mainly due to the use of thermosensitive dyes or photosensitive dyes in the yarn. These dyes undergo chemical changes when the temperature or light changes, resulting in a color change.

Thermosensitive dyes:
When the temperature exceeds its trigger temperature, the dye molecules undergo structural changes, changing color. When the temperature returns to the normal range, the dye molecules return to their original structure and restore the color. For example, thermochromic yarn changes color when the temperature rises or drops from 31 degrees Celsius to that temperature. ‌

Photosensitive dyes:
Photosensitive dyes are sensitive to light of a specific wavelength or intensity. When exposed to light, the dye molecule structure changes, changing color. When the light stops, the color returns to its original state. ‌ For example, photochromic yarn changes color when exposed to sunlight or ultraviolet light, and the color returns when the light source is lost.