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Bronze is the most popular metal for cast metal sculptures; a cast-metal sculpture of bronze is often called a ''bronze''. Common bronze alloys have the unusual and very desirable property of expanding slightly just before they set, thus filling the finest details of a mold.
The strength and lack of brittleness (ductility) of the material is an advantage when figures in action are to be created, especially when compared to various ceramic or stone materials (see marble sculpture for several examples). These qualities allow the creation of extended figures (as in ''Jeté'', bellow right), or figures that have small cross sections in their support (such as the equestrian statue of ''Richard the Lionheart''), both shown to the right. The value of the bronze for other uses is disadvantageous to the preservation of bronze sculptures; few large ancient bronzes have survived as during wartime many were remelted to make weapons or to create new sculptures commemorating the victors, while a far larger portion of contemporary stone and ceramic sculptures have survived, even if only in fragments subsequently reassembled.

The great civilizations of the old world worked in bronze for art, from the time of the introduction of bronze for edged weapons. The Greeks were the first to scale the figures up to lifesize. Very few examples exist in good condition of these cast works. The seawater-preserved bronze, now called "The Victorious Athlete" is a fine example but painstaking efforts were required to bring it to its present state for museum display. Far more Roman bronze statues have survived. The ancient Chinese, from at least 1200BC, knew both lost wax casting and section mould casting, and in the Shang dynasty created many large ritual vessels covered with complex decoration which have survived in tombs. Over the long creative period of Egyptian dynastic art, small lost wax bronze figurines were made in large numbers and several thousand of them have been conserved in museum collections. From these beginnings, bronze art has continued to flourish up to the present.

Contents

Process

Lost wax method

Creating large sculptures

Finishing

Sculptors

People

Abstract and symbolic

Animals

See also

External links

Process

The manufacture of bronzes is highly skilled work, and a number of distinct casting processes may be employed, including lost-wax casting (and its modern-day spin-off Investment Casting), sandcasting and centrifugal casting.

Lost wax method

In the lost-wax casting (Also known as Investment Casting) method, the artist starts with a full-sized model of the sculpture, most often a non-drying oil-based clay such as plasticine™ model for smaller sculptures or for sculptures to be developed over an extended period (water based clays must be protected from drying), and water-based clay for larger sculptures or for sculptures for which it is desired to capture a ''gestural'' quality - one that transmits the motion of the ''sculptor'' in addition to that of the ''subject''. A mold is made from the clay pattern, either as a piece mold from plaster, or using flexible gell or similar rubber-like materials stabilized by a plaster jacket of several pieces. Often a plaster master will be made from this mold for further refinement. Such a ''plaster'' is a means of preserving the artwork until a patron may be found to finance a bronze casting, either from the original molds or from a new mold made from the refined plaster positive.

Once a production mold is obtained, a ''wax'' (hollow for larger sculptures) is then cast from the mold. For a hollow sculpture a core is then cast into the void, and is retained in its proper location (after wax melting) by pins of the same metal used for casting. One or more wax ''sprues'' are added to conduct the molten metal into the sculptures - typically directing the liquid metal from a pouring cup to the bottom of the sculpture, which is then filled from the bottom up in order to avoid splashing and turbulence. Additional sprues may be directed upward at intermediate positions, and various vents may also be added where gases could be trapped (vents are not needed for ceramic shell casting and the sprue can be simple and direct). The complete wax structure (and core, if previously added) is then invested in another kind of mold or shell, which is heated in a kiln until the wax runs out and all free moisture is removed. The investment is then soon filled with molten bronze. ''The removal of all wax and moisture is a critical step, to prevent the liquid metal from being explosively ejected from the mold by steam and vapor.''

Students of bronze casting will usually work in ''direct wax'', where the model is made in wax, possibly formed over a core, or with a core cast in place, if the piece is to be hollow. If no mold is made and the casting process fails, the artwork will also be lost. After the metal has cooled the external ceramic/clay is chipped away, revealing an image of the wax form, including core pins, sprues, vents, and risers. All of these are removed with a saw and tool marks are polished away, and any interior core material is removed to reduce the likelyhood of interior corrosion. Any incomplete voids, due to gas pockets or investment inclusions, are then corrected by welding and carving. Finally the resultant small defects where sprues and vents were attached are filed or ground down and polished.

Creating large sculptures

For a large sculpture the artist will usually prepare small study models until the pose and proportions are determined. An intermediate sized model is then constructed with all of the final details. For very large works this may again be scaled to a larger intermediate. From the final scale model, measuring devices are used to determine the dimensions of an armature for the structural support of a full size temporary piece, which is brought to rough form by wood, cardboard, plastic foam, and/or paper to approximately fill the volume while keeping the weight low. Finally, plaster, clay or other material as described above is used to form the full size model, from which a mould may be constructed. Alternatively, a large refactory core may be constructed, and the direct wax method then applied for subsequent investment. Before the availability of modern welding techniques it was usually necessary to cast large sculptures in one piece, with a single pour. With the availability of welding, a large sculpture may be cast in pieces which are then assembled and permanently joined.

Finishing

After final polishing, various corrosive materials may be applied to form a patina, a process that allows some control over the color and finish.
Another form of sculptural metal art to use bronze is ormolu. Ormolu is a finely cast soft bronze that is then gilded (coated with gold) which results in a matte gold finish. Ormolu was popularized in the 18th century in France and is typically found in such forms as wall sconces (wall mounted candle holders), inkstands, clocks and garnitures. Ormolu wares can be identified by their matte gold finish and clear ring when tapped, this indicating the underlying bronze as opposed to a cheaper metal alloy such as spelter or pewter.

Sculptors

★ Benvenuto Cellini

★ Donatello

★ Lorenzo Ghiberti

★ Giambologna

★ Leone Leoni

★ Adriaen de Vries

★ David Ascalon

★ John Bridgeman

★ Jean-Baptiste Carpeaux

★ Czesław Dźwigaj

★ Alfred Gilbert

★ Maggi Hambling

★ Martin Mayer

Modern:

★ Henry Moore

★ Enzo Plazzotta

★ Auguste Rodin

★ Stanisław Szukalski

★ Lorado Taft

★ Bill Toma

★ George Tsutakawa

★ Gerard Tsutakawa

★ Felix de Weldon

★ Leonard Wells Volk

★ Harry Weber

People

★ Andrew Browne Cunningham, in Trafalgar Square, London, England

★ George VI of the United Kingdom, at Carlton House Terrace, London, England

★ Horatio Nelson, 1st Viscount Nelson - relief panels of his Victory at Cape St Vincent, and Death

★ A conversation with Oscar Wilde by Maggi Hambling, installed in Adelaide Street, near Trafalgar Square, London in 1998

★ ''Shepherd and Sheep'' by Dame Elisabeth Frink Paternoster Square

★ ''Young Dancer'' by Enzo Plazzotta, on Broad Street, London

★ ''Temperance'', a statue atop a drinking water fountain to the north end of Blackfriars Bridge, London

★ In the National Statuary Hall Collection, United States Capitol, Washington, 55 statues, including:

★
★ Edward Lewis Bartlett

★
★ George Clinton

★
★ John Campbell Greenway

★
★ Ernest Gruening

★
★ Eusebio Francisco Kino

★
★ Joseph Wheeler

Abstract and symbolic

★ Henry Moore bronzes

Animals

★ Charging Bull - by Arturo Di Modica, in Bowling Green park near Wall Street in New York City

★ Mustangs at Las Colinas

★ Nelson's Column - Sir Edwin Landseer's Lions guard the diagonals

See also

★ List of artworks

★ List of sculptors

External links

★ MMA exhibition of Shang Dynasty ritual vessels

★ Flash animation of lost-wax casting process

★ LOST WAX CASTING PROCESS EXPLAINED

★ The history of bronze casting