Some unsafe ceramic tableware, more problems are glaze. So what is glaze? What glaze or process is safe? Glaze refers to a thin glassy layer uniformly covering the outer surface of ceramic or enamel vessels, usually made of silicate compounds, and then cooled at high temperature. The glaze of ceramic products is composed of a ceramic layer and a glaze layer. The glaze layer is covered on the surface of the ceramic layer by mixing nano materials and glaze slurry. Because nano materials are added to the glaze, ceramic products can dispel peculiar smell, release negative ions, increase energy and strengthen physique in application, which will play a certain health care role for users.
The main component of the glaze is silicon dioxide, which is thinly covered on the ceramic surface, equivalent to a layer of glass. Glaze, like ceramic clothes, plays the role of anti pollution and easy cleaning. Another important point is beauty. Glaze is an important aesthetic factor of ceramics, especially porcelain glaze, which is varied and beautiful. Generally, it can be divided into green glaze, white glaze, black glaze and colored glaze. In the ceramic glaze, it is necessary to add something called a melting agent to promote the complete melting of the glaze in the firing process, thereby forming a glassy substance. There are many kinds of melting agents. A lead based glaze contains about 20% lead oxide. This kind of glaze is soft and unstable. If it is used to store food, it is easy to cause lead pollution. The melting point of lead glaze is very low, and it is used in low-temperature pottery, such as Tang tri colored pottery and colored glaze. Although the State prohibits the use of lead glaze, some small workshops still produce lead glaze vessels. If you encounter pottery of unknown origin with bright glaze, opaque and low sound, you'd better not buy it as tableware.