2. Soak your feet with mugwort leaves, and your feet will turn black. Generally, the water temperature of soaking feet is too high, which leads to cryogenic burns. Generally speaking, human skin has a tolerance. When the water temperature is 70 degrees, you may be scalded if exposed to 1 min. Water temperature of 60 degrees, exposed for more than 5 minutes may also be scalded.

3. Therefore, when the water temperature is slightly hot, the human body does not feel obvious, and the skin cannot react quickly in a short time. If the time is too long, the capillaries will expand, and the leaves of Artemisia argyi will turn black, which has a certain dyeing effect and is easy to lead to pigmentation and black skin.