Qantara Qantara

Ceramics

In Byzantium

 

From the fourth to the seventh centuries, potters in the Christian East were influenced by their Roman counterparts. They produced tableware, especially sigillated ceramics, culinary ware, and amphorae, using Roman examples and techniques. From the seventh century, artisans in Constantinople applied a lead glaze on the ceramic whiteware they produced. They gradually broke with the Roman tradition to produce (from the ninth to the middle of the fifteenth centuries) different types of redware for transport, storage, the kitchen, and the table. In terms of the technique and style of the work and the iconography they used, Byzantine potters were little influenced by their counterparts abroad. They used simple processes for producing and decorating the work—processes that remained unchanged without any major innovations for nine centuries. The contribution from abroad—from the Islamic world and the Christian West—was very limited.

 

At the end of the twelfth century, a new tool appeared in the Byzantine workshops—the tripod. This was a small support with sharp edges, modelled by hand or cast which, when inserted between the open shapes (such as bowls), enabled them to be stacked for firing. Shards from unsuccessful firings placed between adjacent objects and small, roughly made clay cylinders prevented objects from bonding during firing. They were in part replaced by small supports whose use in Byzantium became common but not systematic. The use of this tripod support is very old in the Far East—Chinese works dating from AD 220 bear marks indicating it was used at that time. Muslim merchants probably introduced this tool into the Middle East. In the ninth century, Iranian ‘three-coloured’ pots bear the three characteristic marks left when the support is removed, and there is evidence that they were used in the tenth century in Susa in Mesopotamia, and in Central Asia in the Samarkand workshops and fortresses. In the Levant, potters used this support in the thirteenth century, but it wasn't until the fourteenth century that it was used in Egypt. The separator rods, found in Serres in Macedonia, show that the Byzantines used an Islamic type of oven (from the end of the thirteenth to the beginning of the fourteenth century), but the ceramics produced in this workshop remained faithful to the Byzantine tradition.

 

In the middle of the thirteenth century, white slip, incision, and lead glaze techniques were transmitted from the Byzantine workshops to the Italian centres of Liguria and Venetia—regions that maintained close relations with Byzantium during this period—, which produced such works as the Graffite arcaiche tirreniche of Savona and vessels of the San Bartolo and Spirale cerchio varieties from Venice. Potters in Byzantium didn't remain sealed off from Islamic stylistic influences. The first sign of eastern influences in Byzantine pottery dates from the tenth to the eleventh centuries: the decorations on polychrome painted ware were in fact inspired by Sassanian works. They were applied to the pottery with the aid of luxury Byzantine silks whose iconography, during this period was heavily influenced by the contemporary Iranian works that prolonged the Sassanian tradition. At the end of the eleventh century, in Corinth, ceramics produced locally and painted with red slip, seem to have been copies of Islamic painted ceramics with a metallic lustre, even though the techniques used weren't the same. An influence from works in western Persia (tenth to eleventh centuries) is evident in the production of Byzantine earthenware in the twelfth century in the decorative composition and the iconography of the sgraffito category of ceramics. The absence of Persian models in the Byzantine Empire didn't facilitate the transmission of decoration methods and/or skills. This occurred through other areas of activity or skills were transferred from one artisan to another. Earthenware imported from abroad was often a source of inspiration for the potters, but, although there was trade in ceramics in the Byzantine Empire, it seems to have had little influence on the artisans, who were reluctant to change or adapt their production. Between the thirteenth and fifteenth centuries, proto-majolica from Campania and Apulia—Ramina Manganese Rosso, Roulette Ware, Spirale-cerchio, Metallic Ware, and Graffita, produced in the workshops of Venice and the surrounding region—were marketed on Greek sites that had passed under Frankish control or had close political and economic ties with Italy. These vases were transported by the fleets that sailed from the ports of Venice, Brindisi, and Otranto, forming a bridgehead with the East and the centres where earthenware was produced. Ceramics painted in a metallic lustre and cobalt blue (produced in the workshops in the Valencia region of Spain in the fourteenth and fifteenth centuries), mainly distributed in the eastern Mediterranean, are rare in Byzantium, but are much in evidence on Greek sites where there was contact with the Catalans in the fourteenth century. There have been very few discoveries of eastern pottery in Greece and Anatolia, but there have been a small number of finds in the Empire's capital. Works produced in Fatimid and Mameluke Egypt are very rare, whereas the ceramics produced in North Syria during the Ayyubid period, mostly consisting of productions from Raqqah, are more numerous. Persian Seljuq ceramics constitute most of the works imported from the Muslim world. These included bowls and decanters decorated in moulded, indented, or incised relief under an opaque alkaline glaze, in white or turquoise, some small minaï dishes from the workshops of Reyy and Kashan, and lakâbi plates. The importation of this earthenware to Byzantium was probably due to the fact that Seljuk Turks, who loved decorated earthenware, settled in Anatolia.

 

Some types of Byzantine tableware were also exported to Italy and the Frankish states in the Levant. Discoveries of Byzantine earthenware are mainly located in the large trading centres, especially in Venice. In the twelfth century, it replaced the Islamic productions from the Maghrib, Sicily, and Egypt, which were highly prized in the peninsula during this period. In the Near East, small numbers of Byzantine ceramics from the twelfth and thirteenth centuries were also traded in the Frankish states. They were mainly distributed in coastal areas.

V. F.

In Islam

 

Ceramic Techniques

Ceramics are one of the major art forms of Islam, and objects made from this material are by far the most common finds on the various archaeological sites. While unglazed, commonplace objects—which are often undecorated—are the most common finds, many other types of ceramic are also excavated: these include commonplace, but glazed, utilitarian objects, which were more luxurious creations that were sometimes decorated using highly sophisticated methods, and even elements of wall coverings.

As traditional forms and techniques were handed on from generation to generation, it’s often impossible to distinguish the very first ceramic pieces of the Hegira from those of preceding periods. However, the Muslim potters quickly introduced new decorative effects to the techniques that were already used in the Roman world, Sassanid Iran, and Egypt. They invented a variety of decorative processes and created a repertoire that—even though it was influenced by regional productions and those brought by the trading routes like the Silk Route—rapidly came to represent a style that could be described as distinctively ‘Islamic’. Style and techniques played an important intermediary role between Far-Eastern and European ceramics, where an orientalizing style developed at the end of the nineteenth century and the beginning of the twentieth century: it was based on various models—ceramics, glasses, and textiles—that originated from Islamic territories.

Ceramic manufacturing processes

The paste

The paste was (and is) made from mixing various materials and has different colours. It is subjected to several operations that facilitate its shaping and firing. There are two main types of paste, which, in transitional periods, underwent variations: clay-paste and stone-paste.

Clay-paste is mainly composed of clay and contains 45 to 50% silica (in the form of silicates). Depending on the impurities the paste contains, its colour can vary from grey-white to pale yellow and even deep red. Usually, to facilitate kneading, drying, and reduce shrinkage after firing, a shortening agent (sand or lime) needs to be added. The blocks of clay are crushed and dampened and then kneaded until the correct consistency is obtained; they are then divided into large slabs. This is followed by the aging phase, in which the clay is left in an enclosed, damp area; this may last for several weeks or even years. Before the material is used it undergoes a final kneading.

The clay-paste was consistently used throughout the centuries.

The stone-paste is composed of 80 à 95% silica and its colour varies from white to greyish white or very pale pink. As its plasticity is low, an organic binder needs to be added (fine clay or gum) before proceeding to the shaping phase, in which often involves the use of a mould. In his treatise from 1301, Abu’l Qasim, descendant of a long line of Kashan potters, provided a recipe that has now been confirmed by laboratory analyses: ten parts of finely ground and pulverized quartz pebbles, one part glaze frit (quartz pebbles and soda extracted from vegetable ashes), and one part fine white clay. In the twelfth century AD, Muslim potters rediscovered and disseminated the use of this paste, which was very widely used in Antiquity, Egypt, and Mesopotamia, but then disappeared for several centuries. In Iran, depending on the amount of frit added to the paste, very hard and translucent objects could be produced that foreshadowed the soft porcelain developed in eighteenth-century Europe.

Shaping the object

This can be done in a variety of ways, depending on the piece’s intended use and the paste utilized.

The most primitive technique involves modelling by hand, for very simple objects or the accessories for moulded or turned pieces (handles, spouts, etc.). Throwing was a process that was probably invented in the fourth millennium BC, and requires a wheel; it comprises a lower wheel controlled by foot and an upper wheel that supports the wheel on which the clay is placed. The potter works by using a regular rotational movement. Depending on the object’s shape or the paste used (siliceous), the object is made in a mould.  The paste is pressed into a mould in one or more parts, which are then joined together by decanted clay, ceramic slip. The object, which is still damp, is then polished by the application of a damp hand or a smooth instrument  (cobble).

The surface treatment of glazed ceramics

To give the surface of the object a different colour to the colour of the paste or to unify it, the potter dips the piece, before the firing stage, into a bath of diluted clay, a slip known as an engobe. From the fourteenth century, certain stone-paste objects were coated in a silica engobe.

To ensure that the object is impermeable (whether it has or hasn’t been dipped in a slip), decorated, and given a glassy surface, it is then covered with a glaze; two principal types of glaze, depending on the flux, were already in use before Islam. The alkaline glaze, which changes easily, contains alkaline and alkaline-earth oxides. The lead glaze, a glaze fused with lead oxides, doesn’t alter so easily. They were chosen according to the desired effects, and intermediary formulae.

The glaze is naturally transparent and colourless. Depending on the requirements, it can be coloured by adding metallic oxides in small quantities, which are produced by grinding and pulverizing certain minerals, or roasting others in special kilns. The coloured obtained and its intensity depend on the glazing and quantity of oxides, of which the most common are: copper (which produces blue with an alkaline glaze and green with a lead glaze), cobalt (deep blue), manganese (light and dark aubergine), iron (various colours, green, yellow, and red), and tin (white, and yellow in the presence of lead). Depending on the epochs and regions, other oxides were used, like antimony, in Tunisia in the eighteenth century.

At the end of the eighth century, potters sought to render the glazes opaque, probably in imitation of Chinese productions transported by land and sea, particularly in the Abbasid Empire and Arabia. Analysis of ninth-century objects attests to the experimentation of the Mesopotamian artisans. In some cases, the opacification is only superficial, due to the incomplete fusion of the alkaline glaze. On others, a beautiful white colour is obtained by adding tin (2%), but the glaze has adhered poorly to the support and has ‘flaked off’. Lastly, a satisfactory result was obtained by combining the lead glaze with tin oxide. As the paste is clay based the object is a real faience. Predating Europe by several centuries, this technique rapidly spread from Iran to Spain—with variants, however, as tin wasn’t available everywhere.

The glaze, whose colour emerges during the firing, was then applied to the object in different ways: in the form of a mix of components, which, when they melt, form a vitreous coat; in the form of pulverized glass which melts a second time during firing and forms a more homogenous coating; and lastly in the form of an aqueous suspension, which is applied by brush, aspersion, or immersion.

Once the object had dried it was ready for the firing stage.

Firing

The kilns excavated on various sites are generally circular and used direct flames. The sides are very thick and the entire structure is buried in the ground. In some cases, they used a downdraft kiln, like at Balis Meskene, in northern Syria. On the same site far fewer smaller kilns were discovered with linings made from refractory clay, and were used to fire objects that are often referred to as eolipiles, but it is known that they had various functions. Texts mention special smaller kilns for objects requiring as second firing, and not in contact with direct flames. Were they muffle kilns (with double walls) or specially constructed kilns?

The kiln had to be packed with great care. To keep the objects separated from one another and ensure the correct heat distribution, a variety of solutions was required, necessitating the prior fabrication of specific instruments, and remains of these have been found in excavated potters’ sites: kiln supports—earthenware pegs—fixed into the kiln lining, tripods, discs, pernettes (which sometimes left tears in the glaze), and earthenware saggars for delicate objects. Different fuels were used, depending on local possibilities and technical requirements.

Firing necessitated close monitoring and involved several phases. Initially it was slow, and then it was taken (depending on the paste used) to between 900–1100°C (not over 600°C for the second firing). It took several days for the kiln’s load to cool down, and then the kiln was opened. The expected results weren’t always satisfactory. A poorly packed kiln or incorrect firing could lead to the collapse, deformation, or explosion of the pieces and could also lead to the objects being stuck together due to the coloured glazes.

These kiln wasters, which were left on the sites, are particularly interesting for archaeologists, because they facilitate the identification of the workshops that produced the ceramic objects.

M. B. -T.