The Ru kiln located in Linru County of Central China's Henan
Province represented another major celadon school that rose in northern
China in the Song Dynasty (960-1279). Ru Kiln refers to a government kiln in
Linru County catering to the Northern Song rulers; the kiln's products were
known as Ru ware porcelain.
Notes in an Old Scholar's Studio by Lu You, the famous Song poet, records the
emergence of Ru ware: "The Northern Song rulers, considering the white porcelain
vessels of Dingzhou unsuitable for use because of their rough mouth-rims, sent
personnel to establish porcelain kilns in Ruzhou to manufacture celadon. In the
eyes of the people of the Song Dynasty, the celadon of Ru ware ranked first in
quality among all northern celadon ware."
The Ru kilns supported the vessels with studs (thin pieces of material used
for supporting objects) during firing so that their mouth-rims and even their
foot-rims were entirely covered with a layer of smooth vitreous (glasslike)
glaze. Ru ware porcelain had a thick lustrous green glaze with a sapphire-like
blue tinge. The vessels had fine crackles (decoration patterns of very small
surface cracks) over the entire surface.
In making celadon at the Ru kilns, the amount of iron in the raw materials
and the reduction flame were carefully controlled, demonstrating maturity in
Chinese celadon manufacture.
A kiln for baking celadon and also Jun ware porcelain vessels were
found in Pingliangsi of Baofeng in Henan Province. Many believed it was a site
of the Song Dynasty's government-run kiln, but this is yet to confirmed as many
of the products that have been found there so far are just ordinary celadon
vessels and light sky-blue glaze porcelain vessels with a green tinge, of which
few measure up to Ru Kiln standards.