This is a normal chemical reaction. At high temperatures, many iron ions dissolve in the soup. Iron ions are easily hydrolyzed to produce iron hydroxide precipitate. Iron hydroxide will decompose into iron oxide and water. Iron oxide is black, so the soup will turn black. It is absolutely harmless to the human body. Don't worry about eating well.1 Avoid blackening of food. When a new iron pot is cooked for the first time, the food will be colored black. At this point, you can avoid food contamination by wiping the tofu residue from the pot a few times. You can also refine it with oil before official use. Method: Pour oil into the wok and heat until hot. Turn off the heat and rotate the iron pot so that the oil sticks to the walls of the pot. Once the oil has cooled, it is ready to be cleaned.4 Skillfully removing grease from an iron skillet. Frying pans accumulate tarred oil from long-term use, and it is more difficult to clean them with alkali or detergent. What should we do, as long as the fresh pear skin on the pan, boiled in clear water, the scales will come off easily.