Using the name secret, on the one hand, it is because the technique of the glazing color is secret and it is dedicated for Tang emperor’s worshiping of Buddha; on the other hand, it is to express a kind of beauty which is beyond description. The formula of secret glaze has been lost since the Tang dynasty, whose descendants Jun, Ru, Yue kilns have imitated it but can't achieve. “The secret color” is exactly what color, which is argued in thousands of years, and its existence is almost a legend.
About the texture and color of the secret glaze, people in Qing dynasty described it as “ its color is similar to Yue Porcelain, but clearer”. From the typical unearthed secret Porcelain, we can find its delicate texture and fine material, gray color, thin wall, smoothness and regularity. About the glaze color, in the Five Dynasties, it was mainly yellow, lustrous, translucent. When it came to the late Tang dynasty, the color tended to be green. And later, green became the main color in replacement of yellow.
Until 1987, 14 pieces secret color glaze treasures were unearthed in underground palace of the Famen Temple, the secret glaze porcelain finally presented in front of the world in the form of real objects. Thus, people can finally see this mysterious glaze and porcelain.