ENAMEL. — In the workshops of goldsmiths, enamels have always had a notable application for the decoration of objects in every age. The glass paste, colored in various ways with metallic oxides and fused, is applied to metal sheets using different processes according to the period and the schools.
I. CLOISONNÉ ENAMEL. — According to this technique, the glass paste is enclosed in cells formed according to the design and the chromatic variations of the individual layers. The technique, of Persian origin, passed to the barbarian workshops within the complex of experiences derived from late antiquity (fibulae from the Civic Museum of Turin, the Pinguente ampulla, Vienna, Museum; the crown of Theodolinda, Monza, Cathedral Treasury, etc.).
In Byzantium, this technique continues but achieves the clearest transparencies in colors, harmonious movement in the golden outline, and perfect coloristic inlays (group of enamels belonging to the oldest altarpiece of the Venice duomo, 11th century; reliquary of the Treasure of St. Mark, etc.). Similarly in Montecassino and Palermo, through the work of Byzantine goldsmiths and their imitators, the technique was applied to rich sacred and profane goldwork (crown of the Norman Constance, Palermo, Cathedral; mantle for the coronation of the Norman kings, Vienna, Kunsthistorisches Museum). In other enamels with figurative motifs, the frequency of the gold wires of the cells decomposed and recomposed the surfaces in a stylistic rhythm that was imitated in painting until the late 13th century (Cimabue, Duccio). Among the works executed in southern Italy and Sicily are: the reliquary cross in the Naples duomo; the evangelary cover in the Capua duomo; the mitre in the Scala cathedral; the cross of Gaeta; the cross of Cosenza; the portable altar of Agrigento, etc. Adopting it directly and indirectly through contacts with the works of the Mosan and Rhenish workshops, this technique was developed, with the graduated coloring of the enamels, into more plastic effects by the school recently localized in Lombardy, to which would belong the binding of the codex of Ariberto from the 11th century (linked to the binding of the St-Denis duomo in the Louvre), the binding of the Vercelli cathedral, the Pax of Chiavenna, etc.
II. CHAMPLEVÉ ENAMEL. — The technique developed in the northern workshops, but of Roman origin, consists in casting the enamel onto copper plates hollowed out according to the design, but lacking true cells. At first (12th century), the figure or decoration is enamelled while the background retains the natural color of the metal; then (early 13th century), the metal tone is reserved for the decoration and the background is enamelled. Under the influence of sculpture, the figure is also modeled in copper, entirely or partially, and applied onto the enamelled surface. In this technique, in the workshops on the Meuse, enamels were produced for goldsmithing works such as the gold cross (10th century) and the reliquary casket of St. Servatius in Maastricht, the portable altar of Stavelot in Brussels (Musées Royaux d'art et d'histoire), etc., always with rare skill. A new decorative repertoire gradually formed, and from contacts with Spanish goldsmithing, Islamic motifs arrived, while other motifs came from the checkered backgrounds of French miniatures: inscriptions in pseudo-Kufic characters, delicate branches with flowers, circles, and crosses adorn the sacred and profane objects produced by the workshops of Limoges, which spread in vast series throughout Europe, also determining various centers of imitation in Spain and Italy (numerous examples in the Cluny Museum, the Louvre, the Vatican Museums, the Bargello, the cathedral of Agrigento, etc.). Among the derivatives are: the Ark of St. Dominic in Silos, a product of the Spanish workshop, the enamel of the ciborium of St. Nicholas in the Bari cathedral, the cross in the Catania Museum, etc. From these enamels, which developed over a chromatic range from blue to sky blue, with greens and reds, influences and some remnants of Byzantine iconography, more frequent in the works of Limoges and Ottonian iconography in the workshops on the Meuse, reached 13th-century painting.
III. TRANSLUCENT ENAMEL. — In Italy, mainly in Siena, a new technique emerged in the second half of the 13th century, after Guccio di Mannaia gave its first example in the famous chalice of Nicholas IV (1288–92) in the Assisi duomo, a technique that soon spread throughout Europe, which Vasari said was executed in bas-relief. With the disappearance of the need for rigid outlines, enamel painting covers with a vitreous and shining surface the gold or silver sheet on which the figure or scene has been delicately modeled in relief.
Among the masterpieces are: the reliquary of the Most Holy Corporal in the Orvieto duomo, executed by Viva and Ugolino da Vieri, and the bust reliquary of St. Agatha, executed by Giovanni di Bartolo of Siena in Avignon, for the Catania cathedral.
IV. PAINTED ENAMEL. — While the technique of translucent enamel received numerous applications in both ecclesiastical and civil goldsmithing, already in the mid-15th century in Limoges a new technique began to be used, consisting in painting with fused enamel on copper plates. Masters such as the Pénicaud family, Léonard Limousin, Pierre Reymond, etc., worked with this technique, bringing it to the highest perfection, and their production always maintained artistic quality.
In Italy, especially in the 18th century, enamel painting was used for sacred medallions, snuffboxes, and various objects. In 19th-century goldsmithing, which began to be produced in series, enamels disappeared, while they were revived with entirely new adaptations by modern goldsmithing, particularly in France, preferring the older techniques that allowed enamel full freedom to compose pure and simple chromatic inlays. — See plates LII–LIII.
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