1. Put the black beans and rice vinegar into the pot, cook the black beans over high heat, then remove the residue and extract the juice. Then boil this concoction into a thick consistency.

2. Apply an appropriate amount of this concoction on your hair each time you dye your hair, and wash your hair after half an hour.

Traditional Chinese medicine believes that black beans are sweet in taste and neutral in nature, and have the functions of promoting blood circulation and diuresis, dispelling wind and detoxification, nourishing deficiency and nourishing blood, and replenishing kidney and black hair. Therefore, there is a basis for using black beans to dye hair. However, in the past, traditional Chinese medicine used black beans to dye hair by taking them internally. This method of external use of black beans for hair dye provides new ideas on how to better utilize the black bean's effect on hair. Rice vinegar can precipitate and concentrate the melanin in black beans and make it adhere to the hair. Therefore, this black bean and rice vinegar liquid can indeed dye hair without causing major harm to the human body.