Cloisonné, an ancient metalworking technique, is a multi-step enamel process used to produce jewelry, vases, and other decorative items.
Cloisonné first developed in the Near East. It spread to the Byzantine Empire and from there along the Silk Road to China. Chinese cloisonné is probably the most well known and ubiquitous. Russian cloisonné from the Tsarist era is highly prized by collectors. Chinese cloisonné is sometimes confused with Canton enamel, a similar type of enamel work that is painted on freehand and does not utilize partitions to hold the colors separate.
First, the artist forms metal (such as copper, bronze, or silver) into the shape of the finished object.
Cloisonné wire, which is pure silver wire usually about .010 x .040 inches in cross section, is bent into shapes that define the colored areas. The bends are all done at right angles, so that wire does not curve up. This done with small pliers, tweezers, and custom made jigs. The cloisonné wire pattern may consist of several intricately constructed wire patterns that fit together into a larger design. Solder can be used to join the wires, but it causes the enamel to discolor and form bubbles later on. Instead the base metal is fired with a thin layer of clear enamel. The cloisonné wire is glued to the enamel surface with gum Tragacanth. When the gum Tragacanth has dried the piece is fired again to fuse the cloisonné wire to the clear enamel. The gum Tragacanth burns off leaving no residue.
Frit (glass crushed to a powder) in a water-based paste is painted into the partitions using an annotated pattern similar to the "paint by numbers" craft technique. After the frit has dried, firing in an oven melts it onto the metal. Several repetitions of the process may ensue to build up the coatings to the height of the partitions. Various colors and transparencies may be used in combination within a single partition to obtain the desired artistic effect.
The glass and a portion of the cloisons are ground and polished to form an even and smooth surface.
The exposed metal is electroplated with a thin film of gold to prevent corrosion and to give a pleasing appearance.