--- title: 'The Song Kilns: Ru, Guan, Ge, Jun' url: 'https://howtotea.me/teaware/materials/chinese-ceramics/song-yao' markdown: 'https://howtotea.me/teaware/materials/chinese-ceramics/song-yao.md' lang: en date: '2026-10-25' description: 'The Song kilns Ru, Guan, Ge and Jun: what made them famous, where crackle comes from, how modern "Ru ware" cups are made and how to tell good ones apart.' --- # The Song Kilns: Ru, Guan, Ge, Jun 宋代名窑 Editors · October 25, 2026 · 9 min read Ru, Guan, Ge and Jun are four of the "Five Great Kilns" of the Song, a list put together only in the 20th century. Today their name goes on mass-made cups and [gaiwans](https://howtotea.me/teaware/brewing-vessels/gaiwan) with a bluish-gray glaze and a web of cracks that tea stains within months. ![A shallow Ru ware dish with a finely crackled bluish-green glaze](https://howtotea.me/images/c/o/v/e/r/cover-1919af98.webp) 宋代名窑 Song kilns sòng dài míng yáo Kilns: Ru, Guan, Ge, Jun (汝官哥鈞) Ru: Qingliangsi, Baofeng, Henan; c. 1086 to the end of the Northern Song Guan: Hangzhou, Southern Song Jun: Yuzhou, Henan; fired at 1250–1270°C Crackle: kaipian (開片), cracks in the glaze Ru standard: GB/T 23397-2009, geographical indication Tea shops sell "Ru ware" as gaiwans and cups labeled "Song glaze." What they share with the Song kilns is the name and the look: a bluish-gray glaze with a web of cracks. To know what you are buying, it helps to know the originals. ## Four of the five The "Five Great Kilns of the Song" (五大名窯) is a 20th-century formula that settled only after the 1950s. In Ming texts the fifth kiln was Chai, not Jun. No Song author ever drew up such a list. The four that come up most often in teaware are Ru, Guan, Ge and Jun. White Ding ware belongs with [Dehua and Chinese white porcelain](https://howtotea.me/teaware/materials/chinese-ceramics/dehua), Longquan celadon with [Yue and Longquan celadons](https://howtotea.me/teaware/materials/chinese-ceramics/qingci), and the [black Jian bowls](https://howtotea.me/teaware/materials/chinese-ceramics/jian-zhan) are a story of their own. The four have little in common: thick, multilayer glazes, and on three of them a web of cracks, kaipian (開片). Beyond that, they go separate ways. ## Ru: the sky blue of the court The kiln stood at Qingliangsi (Baofeng county, Henan). The sky-blue wares began around 1086 and ended with the Northern Song, though the kiln itself ran longer, from the early Song into the Yuan. Song writers said Ru wares were "offered for the emperor's choice, and the rejects could be sold." So some of it reached the market: the monk Huihong mentions Ru bowls for tea alongside Jingdezhen ones. Ru has four telltale traits. The glaze covers the whole piece, foot included. In the kiln it sat on three to six spurs, which left small "sesame" marks (芝麻釘) on the base. The color is sky blue, egg white or gray-blue. The body is pale, straw-colored. The bowl stand in the British Museum (170 mm across, 65 mm high) was fired on five spurs. At the Northern Song court, stands like this held bowls of [whisked tea](https://howtotea.me/traditions/china/history/song-diancha). The story goes that Emperor Huizong dreamed of the sky after rain and ordered that color: "the color of the sky after rain, where the clouds part." The line first appears in the Ming-era *Wu za zu* by Xie Zhaozhe, who passes it on as hearsay and attaches it to Chai Rong and the Chai kiln, not to Huizong and Ru. A beautiful legend, with no Song source behind it. The site was found late. The Shanghai Museum attributed a shard from a field near Qingliangsi in 1986, the Henan Institute of Archaeology dug there in 1987–2002, and the report came out in 2008. On Ru, crackle was tolerated as a flaw: Cao Zhao in 1388 rated pieces without cracks higher. The finest basin in the National Palace Museum in Taipei is prized precisely for its clean glaze. How many pieces survive is disputed. Older estimates put it at 60–70 intact pieces, while the Palace Museum's 2015 recount found more than 90 (21 in Taipei, 20 in Beijing, 16 in the British Museum, 9 in Shanghai).[1](#fn:1) ## Guan and Ge: cracks as a virtue **Guan** (the "official" kiln) worked in Hangzhou under the Southern Song. A thin, dark, iron-rich body carries a thick, multilayer bluish-green glaze with a pinkish cast. Where the glaze thins at the rim, the dark body shows through as the "purple mouth," and the unglazed foot reveals the iron-rich clay, the "iron foot" (紫口鐵足). The crackle is large, the "ice" kind, sometimes likened to "crab claws." The Palace Museum in Beijing considers the Yongzheng-era "Guan-style" copies the best of all. The *Tanzhai bihen* (the attribution of this passage is disputed) describes three stages. First, in the Zhenghe years (1111–1118), an official kiln was set up in the capital. After the court fled south, another went up at the Xiunei Si, where "the wares are perfect, the glaze translucent and bright." A later kiln stood below the Altar of Heaven, and its wares were "no match for the old ones." Jiaotanxia was excavated twice, in 1956 and in 1985–1986. Laohudun was found in September 1996, after locals began secretly digging shards by a stream. **Ge** is a puzzle. The kiln has never been found, no Song text mentions it, and the legend of the Zhang brothers of Longquan was first written down by Lu Shen in 1539. The pieces called "museum Ge" are gray-blue or rice-yellow, on a dark body, with double crackle: large dark cracks and fine light ones. This is known as "golden thread and iron wire" (金絲鐵線). In the 18th century the term was used for Guan; Sun Yingzhou applied it to Ge in 1958 and Chen Wanli fixed it in 1962–1963. In 2017 the Palace Museum showed 113 pieces from its own collection, genuine pieces and imitations together. Residue analysis finds carbon in the large dark cracks of "heirloom" Ge. They were most likely stained after firing, probably with ink.[2](#fn:2) Stained crackle alone proves neither age nor forgery. Ming connoisseurs drew up a ladder of crackle: Gao Lian in 1591 ranked "ice crackle with eel blood" first, "plum petals" second, fine crazing third. That is how a flaw came to have a price. ## Jun: opaque blue with copper The Yuzhou kiln (Henan) made a dense gray body and an opaque blue glaze with red and purple splashes. The blue glaze is a glass that has separated into two phases, so light scatters off microscopic droplets. The red comes from copper fired in a reducing atmosphere. At Juntai the pieces went through two firings, a biscuit firing and then the glaze firing at 1250–1270°C. Cracks that healed over in the kiln are called "earthworm tracks" (蚯蚓走泥紋). Everyday Jun bowls and dishes were made from the end of the Northern Song to the Ming. The famous "official" flowerpots numbered from 1 (the largest) to 10 (the smallest) were long taken for Northern Song imperial ware. Excavations in 2001 and 2004 moved them to the Yuan or early Ming, and thermoluminescence dating at the Shanghai Museum gave about 1340–1370.[3](#fn:3) ## "Ru ware" in your cup Modern "Ru ware" is teaware in the spirit of Ru, and Baofeng revived it. Wang Guoqi built the first trial kiln at Qingliangsi in 1995 and got the sky-blue glaze in 2004. Today the county has almost 200 enterprises, workshops and research organizations turning out more than 10 million pieces a year, coffee cups among them. Imitation is much older: Jingdezhen workshops copied Ge successfully as early as the Xuande reign (1426–1435), and Tang Ying's 1735 stele lists nine "Jun-style" glazes. What does such a cup do for tea? The bluish glaze shows off the color of a green liquor, so people buy these cups mainly for [green tea](https://howtotea.me/teas/green). The same glaze turns up on [gaiwans](https://howtotea.me/teaware/brewing-vessels/gaiwan). Caring for crackle Before the first use, rinse the cup, soak it for about ten minutes in water at around 50°C, then pour boiling water over it. After brewing, discard the leaf, rinse with warm water and dry the cup upside down. Before long storage, let it dry for a full day, since the cracks hold moisture. Do not soak the cup in a bucket of tea for quick color, or the lines will stain unevenly. For general rules, see [teaware care](https://howtotea.me/teaware/care-and-collecting/care). Cracks keep appearing after the piece has cooled. A porous body slowly expands as it takes up moisture, and the glaze cracks again. Autoclave tests showed this delayed crazing as early as the 1930s, and "nurturing crackle" (養開片) relies on it. According to hobbyist guides, line color follows the tea: green tea gives the finest lines, which take longest to grow; [oolong](https://howtotea.me/teas/oolong) gives "golden" ones; [black tea](https://howtotea.me/teas/black) and sheng puer, brown; shou puer, black. None of this has been confirmed in a lab; it is the practice of sellers and hobbyists. The advice "one cup, one type of tea" comes from the same source, since mixing teas leaves dark, uneven lines. ## How to choose without overpaying Antiques do not turn up in shops, and no single trait proves anything. As early as 1388 Cao Zhao warned that a fake Guan is a Longquan piece "without crack lines." In 2021 the British Museum reattributed a "Goryeo" bowl as Ru only after X-ray fluorescence analysis, because Ru and Goryeo glazes are close in composition. Modern ware is simpler. Ask three things: - **Where the raw material comes from.** Under GB/T 23397-2009, "Ru porcelain" as a geographical indication may come only from the protected zone around Ruzhou (part of Baofeng county). Jun has its counterpart, GB/T 23403-2009. - **How it was fired.** The Baofeng standard T/CAS 422-2020 calls for two firings: biscuit at 800–900°C, then about 1200°C in a reducing atmosphere. - **Whether there is a migration report.** The Baofeng standard refers to GB 4806.4-2016 and the test methods for [lead](https://howtotea.me/teaware/care-and-collecting/teaware-safety) and cadmium. When buying, ask the seller for the report. One last point: the "golden thread and iron wire" in an ad for a nurtured cup is not the double crackle of "museum Ge." The first comes from tea; the second arose some other way. ## Common questions How does real Ru ware differ from the "Ru ware" sold in shops? Fewer than a hundred intact Song Ru pieces exist, all in museums. "Ru ware" in a shop is modern teaware in the spirit of that kiln, most often from Baofeng. What matters there is where the raw material comes from, how it was fired and whether the seller has a lead and cadmium migration report. Do you need to "nurture" the crackle? No, it is a matter of taste. The cracks stain on their own with every tea you brew. For an even pattern, keep the cup for one type of tea and dry it after each session. If you dislike the cracks, buy a glaze without crackle. Can you brew shou puer in a crackled cup? You can, but the cracks turn black and the cup looks dirty. Hobbyist guides suggest green tea, lightly oxidized oolong and young sheng puer for this kind of ware. Notes 1. Palace Museum recount, 2015: [Palace Museum Ru ware symposium](https://www.dpm.org.cn/Uploads/File/2018/06/04/u5b14b7222d5b9.pdf). Earlier figures: 65 (Wang Qingzheng, 1987), 67½ (Ma Weidu), about 70 (Yu Peijin). [↩](#fnref1:1) 2. Li Zihan, [Insights into the creation of variable-coloured crackle effect](https://ora.ox.ac.uk/objects/uuid:4147a86e-094d-44e3-9d39-03c89b300e47/files/s2b88qd441), Oxford ORA. The same paper puts "heirloom" Ge at no more than 40 pieces. [↩](#fnref1:2) 3. Dates differ: Rastelli and Li Baoping say Yuan to early Ming, a 2018 Palace Museum publication says early to mid Ming, and the Chinese heritage registry says a peak under Huizong. See [Li Baoping, Numbered Jun wares](https://espace.library.uq.edu.au/view/UQ:194449). [↩](#fnref1:3) --- ## Navigation - Parent: [Chinese ceramics and porcelain](https://howtotea.me/teaware/materials/chinese-ceramics.md) - Previous: [Yue and Longquan celadons](https://howtotea.me/teaware/materials/chinese-ceramics/qingci.md) - Next: [Jian zhan: black Song tea bowls](https://howtotea.me/teaware/materials/chinese-ceramics/jian-zhan.md)