The Ru kilns supported their 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.

The Ru Kiln was only open for a few decades. It was closed when the Northern Song was defeated by the Jin Dynasty in 1127. For this reason, even in the next Southern Song Dynasty, the Ru porcelains were considered very valuable.

Ding Kiln

Ding Kiln originated in the late Tang Dynasty (618-907) and ended in the Yuan Dynasty (1271-1368). The main products of Ding Kiln in the Song Dynasty were white porcelain. It used durable white clay as the roughcast, covered by white glaze. Carving, painting and printing were popular decoration methods for the Ding porcelains. In the early Song Dynasty, the decoration patterns were relatively simple, andby the end of the Northern Song Dynasty the paintings were much more complicated. Some of the Ding porcelains were imperial contributions to the court.

In addition to white glaze, the Ding Kiln also made other glaze colors such as green, black or brown. Sometimes the glaze flowed down along the surface of the porcelain vessels and this phenomena was called the "tear drop".