Cloisons: The Defining Wires of Cloisonné Enamelling
Cloisons: The Defining Wires of Cloisonné Enamelling
How thin metal partitions give cloisonné its characteristic outlined beauty
Cloisons — from the French cloison, meaning partition or compartment — are the thin metal wires or strips bent and fixed edge-on to a metal base plate to create the individual cells that define a cloisonné enamel composition. They are at once structural and decorative: structurally, they contain and separate successive applications of powdered glass enamel during firing; decoratively, their polished upper edges remain exposed after the final surface is ground flush, producing the characteristic dark or bright outlines that give cloisonné its graphic, almost stained-glass quality. Without the cloison, there is no cloisonné — the term itself derives from the same root.
Materials and Dimensions
Cloisons may be fabricated from gold, fine silver, copper, or — in lower-grade commercial work — base-metal alloys. In fine jewellery and high horological enamelling, 24-carat or 18-carat gold wire is strongly preferred. Gold does not oxidise during the repeated high-temperature firings required to build up enamel layers, it bonds reliably to a gold or fine-silver base, and its warm colour integrates harmoniously with the translucent or opaque enamels it borders. Fine silver is the next most common choice and is favoured in Japanese shippo work, where its slightly cooler tone suits the aesthetic conventions of that tradition. Copper cloisons appear in Chinese export wares and in affordable contemporary pieces, but copper's tendency to oxidise at enamel-firing temperatures (typically 750–850 °C) demands careful management of the firing atmosphere.
Wire cross-sections are typically rectangular or square in profile rather than round, so that the flat face bonds squarely to the base and the upper edge presents a consistent, even line. Widths in fine jewellery work commonly fall between 0.3 mm and 0.5 mm; in larger decorative objects the wire may reach 0.8–1.0 mm. Thinner wires allow greater compositional intricacy and finer detail, but they are correspondingly more difficult to shape and more vulnerable to distortion during firing.
Fabrication: Shaping and Placement
The enameller begins with a design drawn to the exact scale of the finished piece. Lengths of wire are then bent by hand — using fine-nosed pliers, tweezers, or purpose-made mandrels — to follow every curve and angle of the design. This stage demands both draughtsmanship and manual precision: a cloison that deviates even fractionally from its intended line will corrupt the composition, and corrections after firing are extremely difficult. Complex figurative or floral designs may require dozens or hundreds of individually shaped wire segments.
Once shaped, each cloison is set in position on the base plate using a temporary adhesive — historically a dilute solution of gum tragacanth or gum arabic, today sometimes a proprietary enamelling medium. The piece is then fired at a relatively low temperature, sufficient to burn away the adhesive and allow the wire to adhere lightly to the base through the surface tension of the softened enamel or through a thin preliminary enamel ground coat (fondant) already applied beneath. In more traditional workshop practice, cloisons are soldered directly to the base using a hard solder compatible with the subsequent firing temperatures, though this approach requires careful matching of solder and enamel expansion coefficients to prevent cracking.
The Role of Cloisons During Enamelling
Once the cloisons are secured, the enameller fills each cell with finely ground enamel paste — different colours in adjacent cells — using a fine brush or quill. The cells act as retaining walls, preventing colours from bleeding into one another during firing. Because enamel shrinks as it vitrifies, each cell must be filled and fired multiple times, typically three to six firings for a fine piece, with each layer built up incrementally. The cloisons must withstand this repeated thermal cycling without shifting, warping, or detaching from the base; this is one reason why the initial bonding stage is treated with such care.
In the finest work — particularly the miniature enamels produced by Fabergé's workshops in St Petersburg and by Geneva-based émailleurs working in the peinture en émail tradition — the cloisons themselves become an expressive tool. Their thickness, curvature, and spacing are calibrated to reinforce the visual rhythm of the design, functioning much as leading does in stained glass or as outlines do in manuscript illumination.
Finishing: Stoning and Polishing
After the final firing, the enamel surface typically stands slightly proud of the cloison tops. The piece is then ground flat using progressively finer abrasive stones — carborundum, then Scotch stone, then Water of Ayr stone — until the enamel and the wire tops are perfectly coplanar. This stoning process reveals the full network of cloisons as bright, continuous lines flush with the enamel surface. A final polish with a wooden buff and rouge restores the gloss of the enamel and brings up the lustre of the wire edges. In some stylistic traditions, particularly certain Japanese shippo variants, the surface is left with a deliberately matte or satin finish after stoning, without the final high polish.
Historical and Cultural Context
Cloisonné enamelling employing metal cloisons has been practised across an extraordinary geographic and temporal range. Among the earliest surviving examples are Byzantine gold-and-enamel objects of the sixth through twelfth centuries, in which gold cloisons of exceptional fineness define intricate figural and foliate compositions. Chinese cloisonné on copper and bronze bases, produced in quantity from the Yuan dynasty (13th–14th centuries) onward and reaching a technical and artistic peak under the Xuande and Jingtai emperors of the Ming dynasty, uses somewhat heavier cloisons suited to the larger scale of decorative vessels and censers. Japanese shippo, which developed rapidly from the mid-nineteenth century, pushed the technique toward extraordinary delicacy, with some pieces featuring cloisons of near-invisible fineness and translucent enamels of great luminosity.
In European fine jewellery, the use of cloisons was revived and refined during the nineteenth-century historicist movements and reached a particular sophistication in the work of the great Russian and Swiss enamel workshops active from roughly 1870 to 1914. The Art Nouveau period saw jewellers such as René Lalique exploit the cloison's capacity for sinuous, organic line, bending wires into flowing naturalistic forms that would have been impossible to achieve by any other enamelling method.
Cloisons in Contemporary Practice
In contemporary fine jewellery and watchmaking, cloisons remain the defining technical element of the highest-grade enamel work. Several Geneva-based ateliers — including those supplying major Swiss watch manufactures — continue to produce miniature cloisonné enamel dials in which gold wires of 0.3 mm or less are bent by hand under magnification to reproduce landscapes, portraits, or abstract compositions in spaces no larger than a postage stamp. The labour involved is considerable: a single complex dial may represent forty or more hours of wire-shaping and enamelling work before polishing begins. This intensity of craft is reflected in the market positioning of such pieces, which command significant premiums over mechanically decorated equivalents.
The cloison thus occupies a dual role in the history of decorative arts: it is a humble technical component — a bent wire — and simultaneously the element that makes one of the world's most demanding and enduring craft traditions possible.