However, it is necessary to leave a little gap in the ceramic bowl for the candle below to prevent the candle from being extinguished at high temperature. Ceramic raw materials are a lot of soil, which is the original resource of the earth and has been refined. Clay is tough, plastic when it meets water at room temperature, slightly dry and grindable; Fired to 700 degrees, pottery can hold water; When it is fired to 1230℃, it becomes porcelain, which hardly absorbs water, and is resistant to high temperature and corrosion. But ceramic soup bowls can't be cooked directly on the fire. Because in order to ensure the good combination of pigments and porcelain, ceramic tableware will add some cosolvents when painting. The cosolvents contain a certain amount of heavy metals such as lead and cadmium, which are easy to contact with food and gradually migrate into food and enter the human body.

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