Do all Ru kilns have "sesame nails"?

Ruyao, one of the five famous kilns in Song Dynasty, was named after its location in Ruzhou. The ceramics it fired are exquisite, enjoying a high reputation in the history of China ceramics. In the late Northern Song Dynasty, Ru kiln specialized in firing imperial porcelain, namely "Ru Ci", or Ru Ci for short. From the first year of Yuan You in Song Zhezong to the fifth year of Chongning in Song Huizong (1086 ~ 1 106), Ru Ci was demoted. Later, it was lost because of the Song and Jin Wars. Ru Ci was "especially rare" in the Southern Song Dynasty. Only 60 pieces handed down from generation to generation in the world are collected by the Palace Museum in Beijing and museums in Taipei, Shanghai, Britain and Japan, and are recognized as rare treasures. Ru Ci has delicate fetal quality and exquisite craftsmanship. Glazed with precious agate, the color is unique and changes with the light. Look at its glaze color, such as sky blue after rain, warm and simple; Touch its glaze, smooth and delicate, like beautiful jade. The surface is as small as a cicada's wing pattern, and there are sparse bubbles under the glaze. In the light, it appears and disappears, such as the morning star flashing, and it is slightly reddish at the junction of fetal glaze, giving people a pleasing aesthetic feeling.

There are two main firing methods, one is Zhi Ding branch firing, and the other is gasket or cake pad firing. All the utensils made in Zhi Ding are glazed and marked with Zhi Ding on the bottom. Zhi Ding is as small as sesame, and it clings to the inner wall of the circle. Zhi Ding is usually white. Zhi Ding numbers are 3, 5 and 6, with 5 as the majority, and 6 Zhi Ding is used for oval narcissus pots. It is rare for the ring fired with washer or cake pad to have no glaze at the whole end.

In the official kiln, plates, bowls and other garden utensils are full of glaze, and the sesame-sized Zhi Ding mark can be seen at the bottom. The cross section of the Zhi Ding mark is white, and the Zhi Ding mark is arranged near the outer edge of the foot. Bottles and other knives, except for a few full glazes, are mostly padded, barefoot and unglazed.