After washing the face skin is very white after a while on the yellow may be due to sebum secretion, air oxidation, skin dehydration and other reasons. 1. sebum secretion: just after washing the face skin will be fresh and clean, and white, with the passage of time, sebaceous glands will gradually secrete sebum, resulting in yellow skin. 2. Air oxidation: sebum and cosmetics will gradually be oxidized by the oxygen in the air, resulting in yellowing of the skin. 3. Skin dehydration: after washing the face will generally skin hydration care, skin in the case of sufficient moisture will appear white, with the gradual loss of water, and can not be supplemented in a timely manner, the skin will appear to be more yellowish. After washing the face skin is very white after a while on the yellow may also be caused by other factors, it is recommended to pay attention to the skin hydration, moisturizing care, if necessary, timely medical care, in order to clarify the cause, targeted care or treatment.