1, put some vinegar in the pot to boil. Wipe the inner wall of the pot with a cloth. You can wipe the cloth with chopsticks. Add appropriate amount of water and turn off the heat after boiling for ten minutes.

2. set the pot on fire and wipe the inner wall with pigskin. Add some edible salt and stir fry. Let the salt stir-fry evenly along the pot wall several times until the salt in the pot turns yellow and black.

3. Salt is a compound composed of metal ions or ammonium ions and acid ions or nonmetal ions. It can promote the metabolism of protein and carbohydrates, the spread of nerve impulses and muscle contraction, regulate the consumption of oxygen by hormones and cells, control urination and thirst, and produce liquids (blood, saliva, tears, sweat, gastric juice and bile). It is also important to produce stomach acid.