Where does the traditional blue come from? How do porcelain workers get better blue materials?

The traditional blue color is developed from cobalt blue lead glaze, which was first seen in Tang tricolor. Pottery workers directly use natural cobalt clay minerals as blue glaze or blue colorant, but the chemical composition of cobalt clay minerals varies greatly from place to place. This difference is mainly because it contains different amounts of iron and manganese, and sometimes a small amount of copper, which leads to different color rendering effects. In the long-term practice, especially in the experience of preparing blue-and-white glaze, porcelain makers gradually mastered the selection, enrichment and processing of cobalt clay minerals, and added a proper amount of lead powder, which achieved good results.