Guan brush washer, D: 12cm. Southern Song, 12-13th C. Christies Ltd.
Guan stoneware bears some resemblance to Ru ware, which was closely associated with Gaozong’s father Huizong. In a way therefore, it acted as a reminder of the legitimacy of Gaozong’s rule. But at a deeper level, Guan (which means "official") is a very different creature, not least because the Hangzhou potters had to learn to work with local materials. For the glaze recipe, they followed more or less the Ru approach, using lime (calcium oxide) as a flux and iron for a bluish tone. But they experimented widely with production techniques, so Guan ware may vary between pale blue, green or tan, and the glaze may look opaque or glassy, depending on kiln temperatures (in the 1200-1250°C range) and atmospheres. The underlying clay bodies are dark and iron-rich, often showing through at the rim and base, a feature known as “purple mouth, iron foot”.
Guan eight-petal lobed dish, D: 17cm. Southern Song, 12-13th C. British Museum
While Ru ware is very subtly crackled, the Guan potters had no such inhibitions. A strikingly crackled glaze is the key feature of Guan, which often looks worn and ancient. The method used to produce this was revolutionary. The southern potters experimented with levels of silica (SiO2) which normally prevents crazing. They discovered that if both body and glaze were low in silica (around 65% instead of 70%), a conspicuous crackle could be achieved under the right firing conditions. Kerr and Wood, not usually given to hyperbole, describe this as “one of the greatest artistic achievements in Chinese ceramic history”.
Foliate dish, described as Ge ware. D: 14cm. Southern Song, 12-13th C. Christies Ltd.
Ge ware (ge as in 哥 or “older brother”) is a famously tricky subject. Many experts believe that what is commonly described as Ge ware is just a paler off-shoot of Guan ware. Ge is not mentioned in any known Song dynasty texts (it's first mentioned in Yuan texts) and no evidence has been found of a separate kiln. The key attributes of Ge (lighter-coloured bodies, more layers of glaze, deeper crackle) can all be explained by variances in production technique – and as we know, the Guan potters were an adventurous lot. The Palace Museum, Beijing, staged an exhibition dedicated to Ge ware in 2017 but even they were careful not to date everything to the Song period. Major auction houses sometimes offer pieces as “Ge ware” (including the ones pictured here) with appropriate caveats. But tellingly, neither of these lovely pieces found buyers at auction, so collectors are obviously cautious too.
Brush washer, described as Ge ware. H: 7.3cm, Southern Song, 12-13th C. Sotheby’s Ltd.
This poses an existential problem for glaze analysis: how do you select a piece for testing if you cannot be sure that it is Ge, because does Ge exist as a separate category in the first place? We know that these pieces also exhibit low silica levels in body and glaze, like Guan. It is worth noting however that the prettiest examples of Ge ware (like the ones shown here) have a distinctive double-pattern of crackle: an inter-woven network of dark and light lines which have been stained for effect, poetically named “gold thread, iron wire”. These intricate pieces argue for Ge’s place among the Five Great Wares. Except of course that they may be Guan.
Conversely, there is plenty of evidence that Longquan existed in the Song period but it is not listed among the Great Wares, probably for two reasons. First, it was not made in an “imperial” kiln but was widely produced in Zhejiang (the coastal province south of Shanghai) for domestic and export markets. And although well-known in the Song period, it was in the early Yuan dynasty that its reputation was at its height and production boomed.
(Left) Longquan mallet vase, H: 17cm. V&A Museum. (Right) Pair of Longquan funerary urns, H: 25cm. British Museum. Southern Song, 12-13th C.
Longquan (a type of stoneware) is one of the most beautiful and influential of the Chinese ceramics. It is the quintessential celadon, with elegant colouring ranging from duck-egg blue to sea green. It was exported as far as Istanbul, where the Topkapi Palace still has a fine collection; while in Japan every tea-master wanted a Longquan vase to accent his exquisitely minimalist tea-house. Celadons are still made in South-east Asia today, in Chiangmai for example. You can find classic designs like the “twin fish” motif - compare my cheap and cheerful modern replica with a 900-year-old version, below.
(Left) Longquan dish, D: 14cm. Southern Song, 12-13th C. British Museum. (Right) Longquan-type dish, D: 14cm. Probably Thailand, 20-21st C.
Like most celadons, Longquan gets its colour from iron fired in a reducing atmosphere but analysis also shows a high level of potassium oxide (K2O) as a flux, hence it is referred to as a "lime-alkali" glaze. This thick unctuous glaze was applied in several thin layers between firings, and if the potters got it right, microscopic bubbles would form and become trapped in the lower layers. As a result, the best Longquan glazes have an unusual depth and complexity. Kerr and Wood point out how difficult it must have been to fire each glaze-layer consecutively without them all melting into one.
Longquan vase with iron-spot decoration, H: 27cm. Yuan dynasty, 14th C. British Museum.
The Longquan potters became more daring with their designs in the Yuan dynasty. For the piece shown above, specks of raw iron were placed on the surface before firing, which resulted in dark brown decorative spots (also seen in wares like Qingbai but the Longquan kilns did it best). These were so popular in Japan that they gave it a name – tobi seiji (“flying spot green-ware”). The trumpet-necked vase shown here from the BM’s Percival David Collection was bought in Japan, where its almost-identical counterpart still resides at the Bridgestone Museum, Tokyo.
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