Take 200g of ordinary flour, add 2g of salt to increase gluten, mix evenly, use 120g of cold water to stir into a large dough, and knead into a softer dough. The dough is relatively soft and will be sticky at first. Knead for a while until smooth and non-sticky, cover and leave for 20 minutes. Get a basin of cold water and start washing your face. When you first wash your face, the gluten will spread out easily. This is normal, so be gentle. Pick up the loose dough and wash it together. During the washing process, you need to change the water several times. The water for washing your face is relatively mixed. When it turns white, you can change the water in a basin until the water for washing your face is relatively clear. Pour the washed face water together and let it settle for 3-4 hours. The water and starch will be clearly stratified. . The time should not be too long. If it is too long, the amount of water in the starch will be too little, and the cold skin will easily crack. In addition, when adding water, it will be difficult to control the proportion. This is very important. After the flour water has settled, pour away the layered water on top, leaving the starch. Pour out as much water as possible until there is a little bit left that cannot be poured out. If you pour it again, the starch will flow out together. This is enough. Mix well and set aside. Take two flat bottom plates, brush them with a layer of oil, add an appropriate amount of starch paste, and shake evenly until the flat bottom plates are evenly covered. It doesn’t have to be too thick. The starch paste must be stirred evenly every time it is used. Boil the water in the pot, put in a flat plate, cover, and cook over high heat for about two minutes, until the cold skin drum is done.