iron

iron. A widely available metal (it makes up about 5 per cent of the earth's crust) that has been used for practical and to a lesser extent decorative purposes since prehistoric times. In its pure state it is soft and silvery white, but it is rarely found in this form, almost always containing impurities, particularly carbon, that affect its properties; the more carbon present, the more brittle the metal generally is. As used in manufacturing and art, iron divides into two main types—cast iron and wrought iron. Cast iron has a high carbon content and is consequently brittle, but it is cheap to produce and resists corrosion well. Wrought iron has a lower carbon content, making it more pliable; it can be hammered into elaborate shapes and has been much used in decorative work, for example in ornamental gateways. Steel is iron that has been purified and alloyed with small quantities of other elements, producing an extremely strong material that is a basic element in modern industry. ‘Cor-Ten’ steel is a proprietary name for a type of ‘self-weathering’ steel popular with some contemporary sculptors. It contains a small amount of copper and acquires a patina that resists corrosion.

Some cast iron sculpture was made in the 19th century, but it was not until the 20th century that iron and steel became important additions to the sculptor's materials. The Spanish sculptor Pablo Gargallo (1881–1934) was one of the first modern artists to use iron, making hammered masks in the material from about 1907. His work helped inspire Picasso to create what has been described as the first steel sculpture, Guitar (1912, MoMA, New York), made of sheet metal and wire. (Iron and steel are not always clearly differentiated; up to about the Second World War, the material used in sculpture was generally referred to as iron, but much of it could probably be more accurately described as steel.) Picasso's sculptural experimentation was an inspiration to Tatlin, the founder of Constructivism, in which steel (along with other modern materials) played a large part, its association with engineering making it appropriate to the creation of forms expressing the machine age. Picasso also played an important part in the development of welded sculpture, collaborating from 1928 to 1931 with Julio González, the main pioneer of the technique. González (who came from a family of metalworkers) taught Picasso welding, in which pieces of metal are joined by melting them together with a blowtorch (first made commercially available in 1901). Welding produces a very strong joint, making it possible to connect pieces of metal in free-flowing, openwork constructions, such as Picasso's Woman in a Garden (1929–30, Mus. Picasso, Paris).

Among the many sculptors influenced by such ‘drawing in space’ was David Smith. Like González, he was highly influential on sculpture after the Second World War, and more than anyone else he established steel as a material with its own expressive qualities, notably by grinding and polishing the surface of his work. Smith also helped encourage the use of scrap metal and prefabricated industrial parts in sculpture. Scrap has been much used in Junk art, for example, and industrial parts in the work of Anthony Caro, who inspired a generation of British abstract sculptors. Minimal artists, too, have made much use of steel, valuing its impersonal qualities.