Special attention: the authentic lotus leaf gray color is burnt yellow. The original text of lotus leaf ash mentioned in the Key to Syndrome Treatment is: burn the defeated lotus leaf, grind it into powder, and mix it with rice soup. If you want to be thin, take lotus leaf ash, that is, burn lotus leaves. Burning retention is one of the processing methods of traditional Chinese medicine, which is to burn the medicine until the outside coke is yellow inside, so that the surface of the medicine is partially carbonized and the inside can emit the original smell, that is, to stay. The yellow lotus leaf ash was calcined by ancient method. Dark brown lotus leaf ash is too carbonized and yellow is not carbonized enough to be eaten.