Celadon is high-fired pottery with a blue glaze.
This glaze is made from the ashes of wood, and the small amount of iron contained in the ashes is reduced to produce the blue color. In China, ash glazed ceramics were already produced during the Shang dynasty, but the glaze was only a dull grassy color because it was not reduced in the firing process. Later, from the Zhou to Han periods, this ash-glazed pottery was made in various regions, and by the end of the Han period, the Yuezhou region, centered on Shaoxing in Zhejiang Province, emerged as a major production area. This was the rise of the Yuezhou kiln. The ash-glazed ceramics produced in Yuezhou had a more refined glaze tone, and the color gradually became more refined from grass green to pale green, approaching celadon. In ancient Chinese literature, it is often referred to as celadon, and it is known to have been highly valued. Celadon glaze from Yuezhou influenced the Zhongyuan region in the middle of the Six Dynasties and led to the establishment of new kilns there, and from the late Heian to the Five Dynasties, the techniques and designs were further refined, and celadon porcelain with a secret color gained high acclaim. In the Song dynasty (960-1279), perfect celadon was produced at the Guan kilns, Ru kilns, Yaozhou kilns, and Longquan kilns, as is well known.
