Cloisonné is an ancient technique for decorating metalwork objects with colored material held in place or separated by metal strips or wire, normally of gold. In recent centuries, vitreous enamel has been used, but inlays of cut gemstones, glass and other materials were also used during older periods; indeed cloisonné enamel very probably began as an easier imitation of cloisonné work using gems. The resulting objects can also be called cloisonné. The decoration is formed by first adding compartments to the metal object by soldering or affixing silver or gold as wires or thin strips placed on their edges. These remain visible in the finished piece, separating the different compartments of the enamel or inlays, which are often of several colors. Cloisonné enamel objects are worked on with enamel powder made into a paste, which then needs to be fired in a kiln. If gemstones or colored glass are used, the pieces need to be cut or ground into the shape of each cloison. In antiquity, the cloisonné technique was mostly used for jewellery and small fittings for clothes, weapons or similar small objects decorated with geometric or schematic designs, with thick cloison walls. In the Byzantine Empire techniques using thinner wires were developed to allow more pictorial images to be produced, mostly used for religious images and jewellery, and by then always using enamel. This was used in Europe, especially in Carolingian and Ottonian art. By the 14th century this enamel technique had been replaced in Europe by champlevé, but had then spread to China, where it was soon used for much larger vessels such as bowls and vases; the technique remains common in China to the present day, and cloisonné enamel objects using Chinese-derived styles were produced in the West from the 18th century. In Middle Byzantine architecture cloisonné masonry refers to walls built with a regular mix of stone and brick, often with more of the latter. The 11th or 12th-century Pammakaristos Church in Istanbul is an example.