Celadon is a term used to describe a ‘family’ of glazes that are a natural product of the process of taking the materials of the Earth, and heating them until they melt. Glazes chart the evolution of mankind’s use of the commonest earth material, clay. In that evolution of vessel making to aid our domesticity, the ability to control fire was the technical measure that allowed clay to be fired to a stage of melt, which we call vitrification.
Simple observation of the internals of a kiln used to fire to higher temperatures to achieve vitrification would have shown the glass-like deposits on the walls of the kiln, and the wares themselves, coming from the ashes of the wood used as fuel. Early pots of the Han Dynasty in China clearly show initial experiments in applying ashes by dusting before firing, and then the obvious next step of mixing ashes as a solution and then dipping or spraying. These are the beginning steps in the evolution of high fired glazes, and Celadon glazes merely represent the apogee of that development: ashes were gradually replaced by limestone, a more consistent and reliable producer of glass, mixed with the two materials that made up the clay body as wares became more sophisticated – china clay (kaolin) and rock.
In this sense, Celadon is an ancient glaze family that tells the story of the development of high fired ceramics, utilizing in a simple yet quite sophisticated way the materials of the earth. At the same time, it remains a very modern glaze, as those qualities of durability, hardness, and a simple, unassuming beauty are the same qualities potters of today are striving to achieve when making utilitarian work.
As a family of glazes, Celadon reached its peak of quality and production in China in the Sung Dynasty (11-12th century). Glazes produced in the north of China were typically more glassy and closer to olive and bottle greens. They were higher fired (close to 1300 degreesC) than the later southern wares, as the geology of north and south China is quite different – clays are more refractory in the north, needing higher temperature to achieve vitrification. Kilns moved to using coal as fuel, which assisted the production of higher firing temperature.
Celadon glazes produced in the south-east of China typically appeared softer, often semi-opaque, fired with wood to no more than 1240C, and in blue/green hues that exuded a quiet luminescence that clearly had a captivating beauty, sought after and treasured by scholars, collectors and everyday users.
My own production of modern Celadon glazes is based on a similar methodology to that used in Sung China: I use a mixture of the body clay, limestone and felspathic rocks that are finely ground in a ball mill for a number of hours. The rocks include material I have found in central West NSW, mainly sedimentary schists containing mica and low amounts of iron. It is the prescence of iron that gives colour to the glazes. To me, what remains critical is that where iron is part of the crystal structure of the material, along with ancillary minerals such as potash and magnesium, it contributes to the growth of very fine bubble development in the melting glass that results in the depth, semi-opacity and soft luminescence that is a hallmark of the best celadons. The tone and hue that comes from using found materials in this way is the unforeseen gift of these materials, and brings with it a sense of place, or location. These qualities are not found in modern industrial methods, where precise amounts of iron oxide are added to refined, white firing materials. One look in the pink coloured glaze buckets of modern Chinese workshops confirms their embrace of 21st century western technology.
My understanding of the origins of our use of the term Celadon (in the West) is that it dates back to the arrival in Europe, more specifically Paris, of consignments of Chinese ceramics that included greenwares, as well as blue-and- white, in the late 17th Century. This was a period of a growing fashion for things Oriental in Europe. It appears that observers writing in ‘news’ magazines of the time were searching for a term to describe these new greenwares: after all, that was how they were described by the Chinese - ‘qing-ci’, greenware. It seems they turned to popular culture: the most popular play in Paris at the time was ‘l’Astree’, by Honore d'Urfe, a tale of thwarted love, in which the hero, Celadon, strode the stage bewailing his misadventure, dressed in a long jade green cape…the play was based on d’Urfe’s novel, produced in the previous century, which was well known and widely read. So, in describing these new ceramics that had appeared, in a colour and depth of glass that resembled green jade, it would have been a simple matter to describe them as ‘green - like Celadon’.
Readers would have immediately ‘got the picture’. This term has remained with us in the West, to the point where Chinese archaeologists have accepted and use the term, even though in their own spoken language and calligraphically they use the term ‘qing-ci’. I believe there is a reference in Homers’ The Iliad to the flow of the river Keledon. The term basically translates as 'twinkling', so it appears to be descriptive rather than nominal. As Homer predates the production of Celadon by some time, it seems unlikely that we would have adopted his reference as our descriptor of Chinese green glazed ceramics.