Iron is a material that does not figure prominently in Chinese art, although it has always been considered a symbol of strength, determination and integrity and justice and widely used in military and agriculture. Iron was known and utilised since the beginning of the 1st millennium BCE in China, although the technique of casting was not mastered until the 5th century BCE. It was only later on, with the invention of double cylinders bellows furnaces by the 4th c. BCE, that the technique advanced and iron tools replaced stone, bone and wooden ones in agriculture.
But cast iron continued to be a brittle alloy of iron with a carbon content ranging from 1.5 to 5 per cent. Its melting point stood at about 1150 degrees centigrades which means that it could not be forged but only cast directly into the desired form. Yet its special qualities were hardness and resistence to corrosion.
Later on, during the Six Dynasties period, a sizeable number of cast-iron Buddhist images began to be produced. By the Tang and Song periods, large sized statues and bells were cast and placed mainly outdoors. The Jiu Tangshu (Old History of the Tang Dynasty) and the Xin Tangshu (New History of the Tang) both recorded the endeavour of Empress Wu Zetian, whose large metallurgical projects have not survived to this day, nevertheless attest the level of effort and time expenditure placed in the creation of iron structures.
The recumbent ox here illustrated is covered with a thin brown patina and the surface is rather coarse, with some cracks and small holes caused mainly by cold shuts. Prominent casting seams are evenly distributed over the whole body. In between the horizontal seams are vertical seams and they all would have originally been covered up with gesso and then painted or lacquered. The rectangular partitions outlined by the seams suggest that the outer clay mould of this iron ox was made out of rectangular tassels. The whole process of creation would have taken quite some time: first a model of the ox with all his details was made of clay over an armature of wood or metal. Once the model dried, another layer of clay was applied to make the outer mould. This outer mould was then cut up in sections with tenons and mortises, numbered and subsequently dried. Iron nails were driven then into the clay model and used as measure, while the model was trimmed down to create the desired space between the outer and inner mould. When the mould sections were reassembled for the casting process, these nails would have also functioned as spacers to hold the outer mould at an equal distance from the core. Due to the complexity of shape to be cast and the amount of melted iron to be used, the casting was done in several steps. First the outer mould was assembled from the legs to the belly; earth was then piled against it and wooden braces installed to stabilise the outer mould and maintain the temperature of the molten iron. Subsequently the mould sections were assembled and the statue cast layer by layer. Throughout the interior and exterior of the ox there are traces of cold shuts formed by molten iron poured by this open-casting method. When the time between two subsequent castings became too long, the molten iron started to solidify before the next pouring, hence causing cold shuts to appear.
This was the casting method utilised throughout the Song period for the production of various outdoor statues, the few extant examples being mostly connected with temple architectures in Henan and Shanxi provinces. The iron oxen found at the site of Pujin bridge near Puzhou city, in Yongji county, Shanxi province, seemed to have served a different purpose, as they were used at the four sides of a bridge to secure the iron chains of the bridge. However, such figures were indeed cast in solid iron, to support the stress, while our ox was cast hollow.
Traditionally, Chinese believed that a statue contained the power to influence its surroundings, and by making a statue, one would be able to bring into existence not only the actual powers of the subject but also its symbolic powers. Faithful to this ideology, since earliest times, oxen were associated with water and came to symbolise water control. An ox (Chin. niu) was the most powerful beast at man's disposal; its strength was invaluable in maintaining clear the water canals system for irrigating and thus preventing floodings. According to the legend, after the Great Yu controlled the waters, he set up an iron ox to tranquilize the waters and repel evil spirits. But these powers were enjoyed not only by oxen, but by all forms of niu – oxen, buffalo (Chin. shui niu) and rhinoceros (Chin. xi niu). Belief in the powers of these so-called “control-the-waters-oxen” (Chin. zhi shui niu) was strengthened by reference to the ancient Five Elements theory. Originally developed in the 4th-3rd c. BCE and refined during the Han period (206 BC-220 CE), this theory explained natural phenomena by the cyclical and mutual interaction of five natural elements. Within this theory, in the Mutual Production Order, metal produced and thus controlled water. This belief in the mutual interaction of water and iron encouraged the production of iron statues for controlling water.
Hence statues of oxen were placed on the banks of lakes and rivers to prevent floodings, or, as possibly in the case of our ox, on a pedestal in front of a Daoist temple associated with water deities. This tradition persisted throughout the centuries. A typical example is the hollow ox at Shanhua temple in Datong, Shanxi province. The inscription gives details of casting date and manufacturer, yet in the local histories it is referred to as one of the seven 'zhi shui niu' originally placed on the west bank of the Yu river.
Our outstanding iron ox stands now placidly recumbent with his tail bent on the right hindquarter, a long -now scrubbed off- inscription on one side, the horns projecting straight from a highly ornate head, reminding us of his past aura, his imposing figure imbued with great somberness, his supernatural symbolism still lingering all around us, searching for waters to placate.
For comparable examples see: Fan Wangli and Li Maolin, “Tang tie niu yu Pujin qiao”, Kaogu yu Wenwu 1991.1: 52-55. Paludan, Ann, “ The Tang Dynasty Iron Oxen at Pujin Bridge”, Orientations 1994.5: 61-68. Barry Till and Paula Swart, “Cast Iron Statuary in China”, Orientations 1993.8: 40-45.