Glossary

Technical and art-historical terms related to the study of works by Antico

Bronze

Bronze
Generally refers to sculpture made from a copper alloy. The technical definition of bronze is an alloy of copper with tin.

Chemical Patination

Chemical Patination
A technique for altering the surface color of a bronze through the application of acids, salts, and heat to produce colored copper compounds.

Pan (detail), model by 1499, cast probably after 1519, bronze, Kunsthistorisches Museum, Vienna, Kunstkammer

Core

Core
Heat-resistant material, typically a mixture of clay or plaster, included in the interior of a wax model for a bronze sculpture to produce a hollow cast.

Core-Pin

Core-pin
Short metal rods or wires inserted through the surface of a wax model into the core. Core-pins hold the core in position inside the mold after the wax has been melted out and while the molten bronze is being poured in. After casting, the protruding pins are either extracted or trimmed.

Direct Lost-Wax Casting

Direct lost-wax casting (roundel)
A casting method that produces a single bronze cast from a single wax model. On a wooden board (A), the design was sketched (B) and a temporary core of clay (C) was applied to areas to be depicted in high relief. A separating layer of cloth (D) was then laid over the entire surface. The cloth was coated with wax (E), which was sculpted into the finished design. The front was then invested in clay or plaster (F), inverted to remove the temporary core (G), and the back invested (H). After the model was prepared, the remaining steps to produce the bronze were similar to those described for indirect lost-wax casting.

Direct Lost-Wax Casting

Direct lost-wax casting (bust)
A casting method that produces a single bronze cast from a single wax model. A generalized core of clay or plaster (A) was prepared for the head and reinforced with iron wire (B). Wax (C) was applied and sculpted into the finished face and hair. The head was then placed on a temporary core of clay (D) for the chest, possibly prepared over a wooden form (E). The drapery and shoulders were modeled in wax (F), which slightly overlapped the wax edge of the head (G). Square iron pins (H) were inserted into the head to support the heavy core. Fine iron wires may have also been inserted into the chest (I) as core supports. The exterior was invested in clay or plaster (J), inverted to remove the temporary core in the chest (K), and the interior invested (L). After the model was prepared, the remaining steps to produce the bronze were similar to those described for indirect lost-wax casting.

Fire-gilding

Fire-gilding
A technique using gold combined with mercury to form a paste, or amalgam, that is selectively applied to the bronze surface. The entire object is heated to vaporize the mercury and deposit a thin layer of gold. The gold is carefully burnished to create a compact, highly reflective surface.

Seated Nymph (detail), probably 1503, bronze with gilding and silvering, Robert H. and Clarice Smith

Indirect lost-wax casting

Indirect Lost-wax Casting
A casting method that produces multiple bronzes from a single model. A wax model was prepared in the form of the desired bronze figure (A). A plaster piece mold would be prepared around the model, then disassembled and the model removed (B). The mold was reassembled, tightly bound, and used to cast a wax copy in several parts. For solid parts, the mold was filled with hot wax (C). For hollow parts, the wax was swirled inside the mold and the excess poured out (D). The remaining wax shell was filled with a mixture of plaster and sand, forming a core, and the wax with its core was then removed from the mold (E). The wax parts were joined and finished, and fine iron wires were inserted to secure the core (F). Channels were added to the wax model to allow the molten bronze to be poured in and gases to escape (G). This assembly was then encased in a plaster mixture (H). The plaster mold was heated and dried. The wax was melted out, leaving a void in the shape of the model, and the plaster core suspended inside by the iron wires (I). Molten bronze was poured in, surrounding the core and filling every part of the mold (J). The channels and core pins were removed from the cast and the surface was cleaned, chased, and polished (K).

Hercules, model created by 1496, cast possibly by 1496, bronze with gilding and silvering, The Frick Collection, New York, Gift of Miss Helen Clay Frick

Mold

Mold
A hollow form used to cast wax or bronze. Clay or plaster is applied to a positive model of the desired figure, creating a negative impression of the surface. A mold can be made of the entire model or created in sections (piece-mold).

Oil-gilding

Oil-gilding
A technique by which thin sheets of gold foil are adhered to the metal using a drying oil or resin. After application, the gold is carefully burnished to create a compact, highly reflective surface.

Antoninus Pius (detail), probably 1524, bronze with gilding and silvering, The Metropolitan Museum of Art, New York, Gift of Edward Fowles, 1965

Silvering

Silvering
A technique for applying a thin layer of silver to the surface of a bronze. Certain silvering techniques parallel those described for fire-gilding and oil-gilding. Silver can also be plated onto the surface of a bronze by using chemical solutions.

Venus Felix (detail), model possibly by 1496, cast c. 1510, bronze with gilding and silvering, Kunsthistorisches Museum, Vienna, Kunstkammer

Studiolo

Studiolo/Grotta
A small private space, sumptuously decorated, built by Renaissance princes in their castles to house their collections of ancient coins and antiquities, gems, natural curiosities, musical instruments, illuminated manuscripts, and other precious works of art.

An inner room, part of Isabella d’Este’s studiolo was named grotta for the low barrel-vaulted ceiling (similar to a grotto) of its first location in the Castello di San Giorgio in Mantua. After 1519 Isabella moved her studiolo and grotta to a new location in the ducal palace, Illustrated here.


Photo Credit: Erich Lessing / Art Resource, NY, Palazzo Ducale, Mantua, Italy

X-radiography

X-radiography
A technique using high-energy X-rays to produce an image of the internal features of an object, such as a bronze statuette. Thin or hollow areas through which the X-rays pass easily appear darker, while thick or solid areas, which partially or completely block the X-rays, appear lighter or white.

X-radiograph of Hercules and Antaeus, 1519, bronze, Kunsthistorisches Museum, Vienna, Kunstkammer

 

X-ray fluorescence spectrometry

X-ray fluorescence spectrometry
A nondestructive technique used to analyze the metallic alloy, gilding and silvering, and the patina of a bronze sculpture. An X-ray beam is directed at a small area, causing the chemical elements present to react in a characteristic manner that can be precisely measured.

Gonzaga Urn, c. 1487, bronze, Galleria Estense, Modena