Although the painted color on the inner wall of ceramic tableware is bright, the colored glaze contains heavy metal elements such as lead, mercury and cadmium. Among them, cadmium and lead are easy to cause liver or other visceral poisoning, while mercury can cause liver and kidney sclerosis. The more glaze and bright color of ceramics, the more compounds such as lead and cadmium. Don't pay too much attention to patterns when choosing ceramic tableware, especially don't use dishes with painted inner walls. Newly bought tableware can be soaked in vinegar for 2~3 hours to dissolve harmful substances in colored glaze. In addition, painted porcelain should never be heated in the microwave oven. Under-glaze colored porcelain is the safest, with more blue-green patterns and less red and yellow. The underglaze color is first painted, then glazed, and then directly fired at high temperature. Because there is no need for low melting point substances, there is no need to add lead to the pigment, and the pigment is not easy to precipitate, which is the safest; The color in glaze is glazed first, then painted, and then fired at high temperature. It does not contain lead, and the pigment is difficult to separate out, which is relatively safe. The place where the underglaze color has a pattern feels as smooth as other places, and the gloss is very good, while the underglaze color is somewhere in between. Although the gloss is good, the feel is not smooth.