The Cizhou kilns in northern China were the first to decorate high-fired wares with colorful, lead-fluxed glazes, which are also called enamels. The addition of lead oxide lowered the melting temperature of enamels, which could not survive high temperatures. This dish was covered with slip and transparent glaze before its first firing. It was then decorated with lead glazes, and fired again at a lower temperature—a process similar to that used for the most expensive Tang dynasty (618–907) glazed mortuary wares.