Glaze is a glassy coating on the surface of a ceramic product. In addition, a glaze is also referred to as a starting material or a mixture of materials that, after being applied to a ceramic product and fired, gives a corresponding coating. Glaze has also been called glaze since the times of Ancient Rus' and in the modern professional environment. Glaze performs practical and artistic tasks: it makes a ceramic vessel almost impervious to moisture and gives the clay a smooth, even surface, which is sometimes used as a substrate for further painting.