Lustreware or lusterware (the respective spellings for British English and American English) is a type of pottery or porcelain with a metallic glaze that gives the effect of iridescence. It is produced by metallic oxides in an overglaze finish, which is given a second firing at a lower temperature in a "muffle kiln", or a reduction kiln, excluding oxygen. The technique of lustreware on pottery was first developed in Mesopotamia (modern Iraq) in the early 9th century. Initially mostly decorated with geometric patterns, by the 10th century an Iraqi style with the design dominated by one or two large figures developed. After the Fatimid conquest of Egypt in 969, it became a great centre of lustreware production until the Fatimid Caliphate fell in 1171, soon after the potter's quarter of the capital Fustat (Cairo) was burned in 1169. It is thought that the Fustat potters dispersed to both Syria and Persia, and lustreware appears there about this time; later the devastating conquests of the Mongols and Timur disrupted these industries. The technique had spread to al-Andalus (the Islamic Iberian Peninsula). Hispano-Moresque ware in lustre was mostly produced in Christian Spain, especially in the region of Valencia – in particular Manises – and later Barcelona.
Lustre appears in Italian maiolica around 1500, and became a speciality of two relatively minor pottery towns, Gubbio, noted for a rich ruby-red, and Deruta. Around 1550 an even smaller town, Gualdo Tadino, also began to make some, for about a century, which was the last Renaissance lustre, Gubbio having stopped about 1570, and Deruta around 1630. There was a revival in England and other European countries in the late 18th century, when the techniques had largely to be reinvented, continuing into the 19th and beyond. Meanwhile, Persian lustre, after very little production since the 14th century, revived under the Safavids between about 1650 and 1750, for elegant vessels, especially vases and bottles, densely painted with plant-based designs.
The lustreware effect is a final coating applied over the ceramic glaze, and fixed by a light second firing, applying small amounts of metallic compounds (generally of silver or copper) mixed with something to make it paintable (clay or ochre). This is then fired in a reducing atmosphere at a temperature high enough to "soften" the glaze from the first firing, and break down the metallic compounds, leaving a very thin ("perhaps 10 or 20 atoms thick") layer that is fused with the main glaze, but is mainly metal. Lustreware normally only uses one colour per piece, and the range is limited – a "gold" derived from silver compounds was historically the most common.
Process In the classical process to make lustreware, a preparation of metal salts of copper or silver, mixed with vinegar, ochre, and clay is applied on the surface of a piece that has already been fired and glazed. The pot is then fired again in a kiln with a reducing atmosphere, at about 600 °C. The salts are reduced to metals and coalesce into nanoparticles. Those particles give the second glaze a metallic appearance. The process has always been expensive and rather unpredictable, always requiring two firings, and often the use of expensive materials such as silver and platinum. The very thin layer of lustre is often delicate, and many types of lustreware are easily damaged by scratching removing the metallic layer, or by contact with acids, probably over time even the mild acids in food. Lustreware has therefore always been for display and occasional rather than heavy regular use, although by the 19th century it could be relatively cheap. Many pieces show the lustre effect only working correctly on parts of the surface, or not at all. Apparently these were still regarded as fit for sale.
Islamic lustreware
Precedents in glass Lustre decoration was first used as a glass-painting technique. Lamm (1941) and Clairmont (1977) placed the origin of motifs appearing on lusterware decoration in Coptic Egypt, however, this hypothesis is disputed. Staining glass vessels with copper and silver pigments was known from around the 3rd century AD, although lustreware technology probably began sometime between the 8th and 9th centuries AD. The earliest recipe for luster production appeared in 8th century AD "Kitab al-Durra al-Maknuzna" by Jabir ibn Hayyan. Much of the knowledge of the behaviours of metallic compounds in turn came from metalworking, where cheaper substitutes for gold in gilding had been developed much earlier. A fragment of lustre glass from Fustat is dated to the 779–780, and a bowl (Corning Museum of Glass) was made in Damascus between 718 and 814; otherwise we know little of the history of the technique on glass. Lustre was used in Islamic glass only briefly, and never spread to other areas as lustre on pottery did. A similar technique was used to make iridescent Art Nouveau glass, with more of a "rainbow" effect than a single shiny colour, from the late 19th century.
Mesopotamia
… excerpt ends here. Continue reading the full article.
