Byzantine Enamel and Metalwork

The most expensive Byzantine art was not painting. A gold reliquary set with cloisonné enamel plaques represented an investment of precious metal, imported stone and highly specialised labour that no panel or fresco could approach, and it was this work — not icons, not architecture — that western visitors described with the most open envy.

It is also the material with the worst survival rate. Gold and silver objects are the first things melted in a crisis, and the Byzantine state melted its own regularly: Heraclius borrowed the church plate of Constantinople to pay for a war, and later emperors did the same. What survives does so largely because it left the empire, most of it after 1204, which is why the greatest single assemblage of Byzantine enamel is on an altarpiece in Venice.

Cloisonné Enamel

Enamel is powdered glass fused to metal by heat. In cloisonné, the technique the Byzantines brought to its highest point, the design is first outlined in thin gold strips (cloisons) soldered or set on edge on a gold base, and the resulting cells are filled with powdered glass of different colours and fired, usually several times, then ground flat and polished.

Two variants are distinguished:

Full-ground (Vollschmelz). The whole surface of the plaque is enamelled, including the background. This is the earlier technique, dominant to about the tenth century.

Sunk-ground (Senkschmelz). A recess is cut into a gold plate and only the figure is enamelled, leaving polished gold as the background. This is the classic middle Byzantine method and produces the characteristic effect of a figure in brilliant colour floating on a plain gold field — the same idea as the gold ground in painting, executed in metal.

The palette is limited and instantly recognisable: translucent deep blue and green, opaque red, turquoise, white, and a purple used for imperial garments. Faces are built from pale flesh-toned enamel with a few gold lines for features, at a scale where the whole head may be five millimetres across.

The technical demands are severe. Gold, glass and the various colourants all expand differently with heat; a plaque must be fired repeatedly at temperatures high enough to fuse the glass without melting the cloisons or cracking the earlier layers. That it was done routinely, at miniature scale, for centuries, says a good deal about the depth of the craft tradition in Constantinople.

Reliquaries

The most important class of Byzantine metalwork is the reliquary, and above all the staurotheke, the container for a fragment of the True Cross. Relics of the Cross were the empire’s most prestigious diplomatic gift, and the boxes made to hold them are the showpieces of the craft: sliding lids, cross-shaped cavities, enamelled saints on every surface, inscriptions in gold.

The Limburg Staurotheke, made in Constantinople between 945 and 959 and now in the cathedral treasury at Limburg an der Lahn in Germany, is the outstanding survivor. It names Constantine VII and Romanos II in its inscription, and a second inscription records its remaking by the proedros Basil, a bastard son of Romanos I. It reached Germany after 1204, taken from the Pharos chapel of the Great Palace by a knight of the Fourth Crusade.

The practice and meaning of relic cult, which drove this entire industry, are described in relics and pilgrimage in Byzantium.

Liturgical Silver

Churches required chalices, patens, spoons, censers, lamps, book covers, processional crosses and revetments for icons and altars. Much of this was silver, and a great deal of it was made in state-supervised workshops.

A remarkable administrative detail makes early Byzantine silver unusually datable: from the late fifth to the mid-seventh century, silver objects were stamped with a series of five control marks, including a monogram of the reigning emperor. Roughly a hundred and fifty stamped pieces survive, and they can be dated to within a reign.

The great hoards — the Sion treasure from Lycia, the Kaper Koraon treasure from Syria, the Riha and Stuma patens — are church plate buried in the seventh century, presumably during the Persian and Arab invasions, by people who did not come back for it. They show provincial Syrian churches equipped with silver of very high quality, which changes the picture of where wealth and craftsmanship were located before the conquests.

Icon Revetments

From the eleventh century it became normal to cover a painted icon with a worked metal sheath — the riza or oklad — leaving the faces and hands exposed and clothing the rest in repoussé gold or silver, often with enamel and gems. The practice is frequently criticised as an obscuring of the painting, and it did lead to panels being punched with nail holes and abraded.

The intention was the opposite of concealment: the metal was a material act of honour, the visible expression of a congregation’s or a donor’s veneration, and revetments were frequently added, replaced and upgraded over centuries. Several famous icons, including the Vladimir Mother of God, spent most of their history under metal.

The Pala d’Oro

The single greatest concentration of Byzantine enamel is the altarpiece of San Marco in Venice, the Pala d’Oro: some two hundred and fifty enamel plaques of various dates, set in a gothic gold frame with over a thousand gems. Most of the Byzantine enamels came to Venice in 1204 from the monastery of the Pantokrator in Constantinople. It is described fully in the Pala d’Oro, and the building that houses it in St Mark’s Basilica.

Other Metal Arts

Bronze doors. Constantinopolitan workshops of the eleventh and twelfth centuries exported cast bronze doors inlaid with silver to Italy — Amalfi, Monte Cassino, Salerno, Atrani, and the basilica of San Paolo fuori le Mura in Rome. Several survive and carry the names of their Constantinopolitan makers, making them among the few signed Byzantine works of any kind.

Steatite and rock crystal. Carved soapstone icons and crystal vessels mounted in gold formed a middle tier of luxury goods below gold and enamel.

Coins and seals. The imperial mint and the lead seals attached to official documents constitute the largest surviving body of Byzantine metalwork by number — tens of thousands of seals are known — and they are the principal evidence for the structure of the administration. The coinage is covered in Byzantine coinage.

The Transmission West

Byzantine enamel was the model for the medieval western tradition. Ottonian goldsmiths copied it directly; the workshops of the Meuse valley and the Rhineland in the twelfth century learned from imported Byzantine pieces; Venetian and Sicilian workshops employed Greek craftsmen. When the crusaders sacked Constantinople in 1204 they took, among much else, the largest concentration of enamel and goldwork in the world, and the treasuries of European cathedrals were stocked from it — a redistribution described in the Fourth Crusade.

That is the reason the subject is studied largely in western museums, and the reason any account of Byzantine metalwork is an account of what happened to survive in other people’s churches.

Making a Cloisonné Plaque

The sequence is worth setting out, because it explains why the objects are so rare and so expensive.

1. The base. A thin gold sheet, hammered to an even thickness, with the design outline scribed onto it. For sunk-ground work, a recess is cut or raised so the figure sits below a polished gold field.
2. The cloisons. Gold ribbon perhaps 0.1–0.2 mm thick and a millimetre or so deep is cut into short lengths, bent to shape with fine pliers against the drawing, and set on edge. On the finest work each fold of drapery and each feature of a face is a separate ribbon.
3. Fixing. The cloisons are held by a flour paste or fixed with a trace of solder — soldering risks melting them, so much Byzantine work appears to rely on the enamel itself to lock them in place at the first firing.
4. Charging. Each cell is filled with ground glass of the required colour, applied wet with a fine spatula or quill, cell by cell.
5. Firing. In a furnace at roughly 750–850°C, until the glass fuses. The charge sinks as it melts, so cells must be refilled and refired, often three or four times.
6. Finishing. The surface is ground flat with abrasive stones, then polished, so that glass and gold cloisons lie in one plane.

Every stage can destroy the work. Different colours mature at different temperatures; gold softens near the working range; and a cracked plaque cannot be repaired, only replaced. A face five millimetres across, built from a dozen cells separated by wires a tenth of a millimetre thick and fired four times, represents a success rate that must have been well short of total.

Reading an Inscription

Byzantine metalwork is unusually talkative, and the inscriptions carry most of what is known about the objects.

They typically give three things: the donor’s name and titles, a metrical prayer, and sometimes the occasion. The Limburg Staurotheke carries two — one naming Constantine VII and Romanos II, another naming the proedros Basil who had it remade — and the pair records both the object’s origin and its later history.

The verse is normally in twelve-syllable iambic lines, the standard Byzantine epigrammatic metre, and is frequently of real literary quality. A substantial body of these epigrams survives independently in manuscript anthologies, which occasionally allows a lost object to be reconstructed from its inscription alone.

For the historian this makes metalwork the best-dated class of Byzantine art. A silver paten with a fifth-century control stamp and a donor inscription fixes a date, a place and a person, which no fresco or icon does.

The Silver Stamps

The stamping system deserves its own note, because nothing like it existed again in Europe before the modern hallmark.

Between roughly 491 and 641, silver objects produced under imperial supervision carry a set of five control marks, usually on the underside: a monogram, a bust, and inscriptions naming officials, with one element identifying the reigning emperor.

Around 150 stamped pieces survive, and because the imperial element changes with each reign, they can be dated to within a few decades and often to a single reign. They therefore anchor the chronology of early Byzantine silver, and by extension of the ornament and figure style found on it.

The system’s disappearance after about 641 is itself evidence — one of many indicators of the administrative contraction of the seventh century.

• The Pala d’Oro — the greatest surviving assemblage
• Byzantine Ivories — the other great luxury craft
• Relics and Pilgrimage — the cult that drove the industry
• Byzantine Coinage — metalwork at imperial scale
• St Mark’s Basilica, Venice — where much of it ended up
• The Fourth Crusade — how it got there
• Byzantine Iconography — the images the enamellers rendered in glass