Ceramic Technology in the Antiquity

Ceramics have long maintained a widespread standard in society as durable utility items, most often in culinary applications such as plates, bowls, and vessels. The English word ceramic is derived from the Greek keramikos meaning pottery², which is derived from the Indo-European word ker meaning heat³. The etymology suggests that ceramics were initially defined by the use of heat in their manufacturing process, and that pottery, the primary manifestation of ceramics in antiquity, popularized ceramics as a material. Even as humble pottery, however, ceramics were so pervasive in antiquity that they are now useful in drawing conclusions about technology, culture, and society in Ancient Greece and Rome. The development of ceramic processing itself was an integral step in the development of ancient materials technology, and the material properties and ubiquity of ceramics have made them one of the largest sources of ancient archaeological evidence. Ceramics also played a key supporting role in many ancient cultural traditions, and are a good case study for the juxtaposition of crafts and arts. Finally, social views of potters and craftsmen in general are useful for extrapolating the ancients' changing societal values.

Ceramics were one of the most important and ubiquitous materials in antiquity, and played a fundamental role in the development of materials science and materials processing. The earliest archaeological examples of ceramics in the Mediterranean date to approximately 10 000 BCE, and were of fairly poor quality. Techniques of coiling combined with sun-drying were used to create simple shapes, such as pots and jars, that lacked strength and erosion resistance. Around 2000 BCE the first pottery wheels developed, but they were not extensively used until 1200 BCE, towards the end of the Bronze Age. Homer referred to the relatively new existence of pottery wheels in the Iliad⁴. The wheel produced much sturdier pottery than coiling, and allowed vessels to have thinner walls. In general, the thinner the wall of pottery, the greater the skill and craftsmenship required, hence the higher the quality. Herodotus wrote about innovations in the construction of kiln technology⁵, occurring between 650-400 BCE, led to even better pottery through finer temperature control. Terra cotta, clay with various mineral deposits, formed strong chemical bonds when heated, making it virtually indestructible at the molecular level. As a result, much of it has survived as archaeological evidence. The most common type of pottery was heavy, undecorated whiteware, mainly used for eating and cooking. The ancients did have some elegant, decorative pots and eating wares, but these were limited to the upper classes and probably used only for special occasions. After 400 BCE, mould-made ceramics became popular, which utilized a process similar to bronze sculpture-making.

Ceramics were a significant technological development in antiquity since they were one of the first tangible products of civilized society. By definition, the quality of civilization is defined partially by the presence of technology, or at least an advanced state of materials development. Ceramics aided in improving conditions of food, shelter, and water, whose necessity to life made it a sensible technological starting point. Ceramic tableware acted to separate human food from the environment. Pots and pans were required in order to cook food, which broadened the range of available digestible foods. Ceramics also played a large role in the transportation and containment of water and food by allowing significantly better and longer term storage. Storage of food provided incentive to overproduce, since resource security was now possible. In terms of overall society, the capacity for food and water storage likely had a significant effect on the localized increases of populations into economically stable cities.

In terms of shelter, ceramics were formed into roofing tiles to provide protection from elemental damage and sunlight. Since ceramics were virtually indestructible on a molecular level, pottery shards were useful as part of the foundation for roads and houses that developed later on. Most likely, the availability and ease of accessing clay popularized ceramics as a material, since its raw requirements were available to virtually everyone. The development of ceramic processing technology to produce quality materials, such as the invention of the wheel and kiln, are examples of the ancients' ability to apply physics to common problems.

Ceramics were preceded by the use of mud-brick, which was primarily used as a construction material. Mud-brick was a combination of clay, sand, and water formed into a viable material. The use of sun-baking and coiling likely developed directly from mud-brick by experimentation and simply leaving the pottery outside. Reeds, grasses, and other organic harvestable materials were woven into wares, but decomposed fairly quickly and were not as effective at storing liquids at ceramics. The development of textile processing, which resulted in some container items such as water flasks, was fairly industrialized by the 1^st century BCE. Although textile containers had some advantages, especially in that they were not highly brittle, they required considerable processing⁶ and never replaced ceramics as large-scale, permanent storage devices.

The techniques for processing ceramics eventually led to the production of glass, described in detail by Pliny⁷. While glass is considered a ceramic with an amorphous rather than crystalline structure, by modern standards, the ancients realized they were similar due to the similarities of their processing techniques. Extremely hot furnace temperatures were required to process glass, and thus glass developed out of the kiln technology designed for ceramics and copper smelting. More refined techniques for producing brightly coloured glasses with a homogenous consistency were developed in the early Iron Age⁸. Glass blowing, which was invented in the 1^st century BCE, allowed the production of transparent glass and more elaborate shapes with thinner walls⁹. Though glass did control a few niche markets, such as perfume jars, it was a rare material in general, and never attained the ubiquity of ceramics. The difficulty of glass production alone restricted its ownership solely to the elite classes, whereas ceramics, which were usually undecorated and utilitarian, were common to all classes.

The unique physical properties of ceramics made them a highly useful material to both the ancients and modern archaeologists. Because of their widespread use throughout society, the disposal of ceramics in abandoned wells and other landfills have provided modern archaeologists with a great deal of well preserved and chronologically stratified evidence. Other than being extremely resilient, ceramics were useful to archaeologists because their geographic origin could be traced based on the type of clay present in their composition. The types and prevalence of pottery during various time periods was also an indicator of social wealth at the time, since greater wealth indicated more slaves to produce pottery.

The utility of ceramics in antiquity was not limited to pottery, and the Ancient Greeks and Romans held an international reputation in the craft. Pliny discussed several uses of ceramics, including flue ducts and coffins, in context of their popularity and production throughout Asia and Europe:

“Nor are we sated by the presence everywhere of pottery products, with jars devised to hold wine, pipes for water, flue ducts for baths, tiles for roofs, fired bricks for walls and foundations, and items turned on wheels, because of which King Numa set up a seventh guild for potters. Indeed, many even prefer to be buried in pottery tubs after death like Marcus Varro... The greater part of the human race uses pottery vessels. Among table wares, the Samian is praised even now. Arretium in Italy also hold high rank, and – for cups alone – Surrentum, Hasta, Pollentia, and in Spain, Saguntum, and in Asia Minor, Pergamum. In Asia Minor, Tralles has its special products, and Mutina in Italy. Since even nations become famous in this way, these products too are carried this way and that across the land and sea from workshops renowned for the potter's wheel.¹⁰”

Pliny mentioned several key economic players in the ceramics market, besides Athens and Corinth, which are described by geographic location rather than individual craftsmen due to the importance of the type of clay used. Ceramics were also important to many hydraulic engineering projects, and were used commonly as tiles in the Roman bath systems. Large pots called pithoi were sometimes used as temporary housing¹¹.

Besides utilitarian purposes, ceramics became important purveyors of culture and processes in ancient life. Decorated pottery contained a variety of art ranging from depictions of mythology to manufacturing processes and mining to historic battles. Pottery played an essential supporting role one in one of the Greeks' most famous cultural events – the symposium. Ceramics provided a container for wine and characteristic shallow cups for drinking, often adorned with the god Dionysus. The other cultural staple of the ancients – olive oil – also used pottery for its trade, transport, and decanting. Olive oil was so important to ancient culture that it was presented in greatly adorned pots to the winners of the Olympics. Ceramics played an underlying secondary role to many Ancient Greek and Roman traditions, and therefore ceramics were a key element in the formation of ancient culture.

The two most important centres for producing ceramics in antiquity were Corinth and Athens. Economically, Corinth had an extensive trade network and materials entered and left the city on a regular basis. As a result, Corinth became a dominant centre of production for ceramics earlier than Athens. Solon's economic reforms promoted the trade of ceramics in both Athens and Corinth, as pottery was the only viable container for exporting olive oil. In terms of geographic location, both Athens and Corinth were also surrounded by clay beds, and therefore the availability of raw materials encouraged the craft of ceramics. Due to the mineral content of the available clay, Athenian clay had reddish tones due to a high iron content, while Corinthian clay was a softer yellow.

While most pottery was not embellished, two major styles of decorated pottery eventually emerged from Athens. Black figure pottery, which consisted of black figures on a red background, was the first to develop¹². To produce the effect, a slip (diluted version of the clay) was used to paint everywhere on the pot that was intended to be black. The pot was then placed in the oven and allowed to reach a temperature of about 800°C (although there was no device to measure temperature). The vent in the top of the oven was covered to allow the temperature to rise and the oxygen content to be reduced, causing the slip to vitrify. Vitrification is a process of making a material glassy through heat fusion¹³, which caused the entire pot to appear black. The vent was then opened to reintroduce oxygen and lower the temperature. As the pottery cooled, the slip remained black and the rest of the pot turned red. In red figure pottery, which developed afterwards, the process was inverted, producing red figures on a black background¹⁴. The advantage to inverting the procedure was that outlines and details could be drawn in initially, so that much more intricate designs were possible. With the black figure technique, finer details had to be etched in afterwards, resulting in a less attractive final product. The popularity of both the black and red figure styles contributed to the renowned reputation of Attic pottery¹⁵. Extra minerals also were sometimes added to produce others colours of pottery. Other styles, such as white figure pottery, developed with time.

Ceramics are a good example of the juxtaposition of crafts and art in antiquity. In Ancient Greece and Rome, potters were always considered craftsmen, yet in modern society, a very decorative or seemingly frivolous pot may be considered art rather than a utility craft. By modern standards, an artist is loosely defined as someone who demonstrates creativity or imagination and sometimes more strictly denoted as someone who creates something of aesthetic value. The line between art and utility is controversial, however, especially when one considers a utility item such as a pot that also was intended to provide aesthetic value. Can something be both a craft or utility item and a piece of art, or are they mutually exclusive? The Romans instead tackled the problem by breaking society into four general classes, which also reflected a hierarchy of social status: 1) Manual Labour; 2) Entertainment; 3) Education & Youth; and 4) Liberal Arts. Rather than judge 'art' by the final product or even the intention of the creator, the perceived level of skill that was required to perform the task was judged. Potters performed manual labour to create ceramics, hence all potters were considered craftsmen, regardless of the aesthetic value of their work.

Through society's treatment of potters and other craftsmen in general, observations can be drawn regarding societal hierarchies in antiquity. Social values in antiquity were largely determined by notable philosophers and writers reflecting on events of the time, such as Aristotle, and Plato. For example, Aristotle's three categories of knowledge were theoretical knowledge (the exploration of truth and being), practical knowledge (consisting of human action), and productive knowledge (the ability to make something). The categories were designed as a ladder, such that theoretical knowledge was the highest form of study. Since ceramics, by the origin of their name, were an application of a process, they fell into Aristotle's third or lowest category: knowledge for production. In contrast, modern science defines ceramics as non-metallic, inorganic substances with structures ranging from crystalline to amorphous¹⁶. Hence, the modern concept of ceramics suggests that it can be studied as the highest form of Aristotelian knowledge (theoretical knowledge). The freedom of application has allowed modern ceramics to encompass both the levels of pure science, such as studying the molecular composition and behaviour of the material, and applied science, including traditional structural applications and whitewares but also advanced military usages. Arguably, the Greeks' deeply rooted view of ceramics as a craft instead of a materials science limited their appreciation of potters and craftsmen. However, the ancients, including craftsmen, lacked a modern understanding of matter, so it is logical that they perceived ceramics as a craft instead of a higher science.

Throughout Greek history, in particular, changes in the treatment of potters and others who utilized productive knowledge was evidence of changes in the social system. The earliest ceramics, for example, were made during the late Bronze Age. Economically, Greece was in a dark time after the fall of the Bronze Age, and potters were appreciated as their work supported the growth of the community. The application of knowledge to productive tasks and the creation of physical products and technology was an honourable task, and a craftsman was known as a demiourgos or 'one who serves the community'. Both Homer and Hesiod wrote in high esteem of technology and craftsmen. In Works and Days, Hesiod described idleness as being very shameful, since the economy needed working people to progress¹⁷. By the 5^th century BCE, a wealthy aristocracy began to emerge in Greece. The resulting clear division of status and wealth caused manual labour to become slave's work, and consequently no longer an honourable job. Because of money and slave-labour, the elites were free to engage in play-writing, politics, and the military. Potters and other craftsmen had very low social status, and as slaves, were not permitted to vote or partake in society. During this time, craftsmen were called techne banausos, which quickly became a pejorative and vulgar term. Philosophers even viewed writing about manual labour as degrading¹⁸, which likely contributed to the lack of written sources on ceramics production.

The changing view of potters and craftsmen, therefore, was a reflection of ancient social values throughout time. Ceramics existed primarily for utility in antiquity, although they played a supporting role in the development of many characteristic elements of ancient culture. The most common examples of ceramics in ancient society were everyday wares for cooking and eating, but due to their excellent mechanical properties such as strength, hardness, and durability, ceramics were also used for roofing tiles, pipes, flue ducts, and construction. The widespread use of ceramics in Ancient Greece and Rome has also provided modern archaeologists with multitudes of information about the past. Perhaps most significantly, ceramics developed as one of the first technologies from ancient civilized society, and thus played an integral role in both the development of ancient society and Western culture as it exists today.

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