Ceramics

Alfarería
Alfarería
Uso de placas y rodetes
Modelado
Moldeado
Moldeado
Acabado de superficie
Referencias
  • Introduction

    Ceramics is one of the most revolutionary technologies in human history, and the first completely synthetic product to be made by humans. It combines three basic elements: the first is clay, the second additives—organic or inorganic elements found in or deliberately mixed with the clay to make it more workable and prevent breakage under extreme heat—and the third is water, which gives the material a malleable consistency. The step from modelling figures with raw clay to the application of fire to make a solid, durable objectwas the main development that gave rise to this technology. Ceramics are among the materials that best withstand the passage of time, and as such are a major source of information for archaeologists as they seek to learn about the past.

    Many questions about the origins of ceramics remain unanswered. The earliest known evidence of ceramic technology are the clay figures found in Dolní Vĕstonice, a Gravettian Palaeolithic site in the modern day Czech Republic and dating back around 26,000 years. These figures are a very early example of experimentation with clay; thousands of fragments of both fired and raw clay have been found at the site, as well as evidence of a kiln, confirming the existence of sophisticated knowledge and skills in the use of these items. Most of these figurines are the so-called “Palaeolithic Venuses”, small statues of women with exaggerated breasts and abdomens to accentuate their femaleness. Image 1

    The question remains, however, as to when the idea first arose to use clay and other materials to make vessels, a development that would turn a technique into a revolutionary technology. The world’s oldest pottery is the Jōmon tradition, from Japan. The style dates back to between 8000 and 4000 BCE, and is consists of basket-shaped pieces with surfaces showing the imprints of cords and rope coils. Ancient oriental pottery in both China and Japan achieved a high level of sophistication thanks to the emergence of techniques such as glazing and the development of more efficient kilns, which could attain the high temperatures needed to produce porcelain. The introduction of the potter’s wheel, a revolving circular platform on which a lump of clay could be modelled as the base rotates, was another advance in technology that facilitated large-scale production.

    The earliest evidence of ceramic technology in the Old World comes from two sites in the Middle East— Beldibi and Çatalhöyük, both in Southern Turkey—dated at around 6500 B.C.E. These early vessels were hand made from rolls of clay, then rubbed or scraped to attain a more even finish and fired in wood or dung fires. One hypothesis on the birth of ceramic technology in this area links it directly to the development of early architecture in the Middle East, as both ceramic vessels and buildings were made by placing pieces on top of each other to produce the desired form. Image 2

    In general, the rise of ceramics has been associated with the development of agriculture and a sedentary way of life. However, there are some cases of nomads and hunter-gatherers using ceramics, including the earliest known ceramics of the Americas. On the banks of the Magdalena River on the Caribbean coast of Colombia, examples of ceramic work have been found dating back to 3490 B.C.E. The San Jacinto 1 site, located in this riverbank area, is thought to have been occupied for long periods by humans groups that subsisted by collecting wild seeds and hunting small game and deer. Ceramics found here consist of small bowls, pitchers, and globular neckless vases with handles. Image 3

    Valdivia pottery is another expression of early ceramics in the Americas. Artefacts from this tradition have been found at a number of sites on the Santa Elena peninsula on Ecuador’s Pacific Coast. One of the best-studied sites is Real Alto, where a number of finds have been dated between 3000 and 2300 BCE. In earlier sites, such as nearby Altomayo, ceramic figurines have been found that might represent the experimentation stage preceding the development and adoption of ceramic technology. These figurines have features very similar to experimental ones found in Eastern Europe and the Middle East.

    Around a thousand years later, ceramics began to appear in the archaeological record of Mesoamerica and the Andes. Some of these were found around the year 2000 B.C.E. in the Peruvian Amazon’s Ucayali River valley, about the same time the technology emerged in the country’s northern and central coastal regions in association with early agricultural communities and the first examples of monumental architecture.

    In the Mesoamerican region, the development of ceramics is best known from the Tehuacán Valley in Southern Mexico. The emergence of agriculture has been studied intensively at the site, and it is believed that the emergence of ceramic technology was closely related with this change in lifestyle, particularly during the Purrón Phase, from around 2300 B.C.E. The shapes of ceramic vessels found there imitate the stone mortars that were used to grind the first cultivated grains. The most popular and widely used ceramic form across the Mesoamerican region, however, was the tecomate, a gourd-shaped bowl used to store seeds.

    The most widespread early ceramic tradition in Mesoamerica was that of the Ocós, which developed around 3500 B.C.E. in coastal and riverbank sites and resembled the Valdivia tradition. This similarity has sparked speculation that ceramic technology developed across the region through contact among these groups. Most ceramic items were made for domestic use, but some were also used as grave goods or as ornaments, figurines, and musical instruments, giving ceramic artefacts a religious significance among ancient cultures.

    Although the earliest evidence of ceramics in the Americas predates the development of agriculture and a sedentary way of life, this technology certainly was used more intensely in communities that produced their own food and lived in small villages.

  • Coil building

    Today, observation of traditional ceramic making groups that have not adopted the wheel has allowed ancestral ceramic techniques to be reconstructed. Slab pressing and coil building are two of the most common ways of making vessels without a potter’s wheel. Slab pressing consists of moulding relatively flat sheets of clay, either by hand or using tools such as spatulas. This method is mainly used for making symmetrical, non-globular items, as well as large ones.

    The most commonly used technique, however, is coil building, in which thin coils of clay are made by rolling the material with the palms of the hands against a flat surface. The length of these coils is determined by the diameter of the item to be made. The coils are then piled one on top of the other. There are many variations of this technique, but usually long rolls are made and then coiled up in a spiral shape, or shorter rolls are made into ring shapes and built up on top of each other, like the bricks that make up a wall. The first technique generally makes a stronger structure, as the overlap of the coils binds them to each other more strongly, given that the joints between rolls are the weak points where the piece can crack during drying, firing, or usage. To help prevent cracking, potters wet the clay or score lines over contact points so as to strengthen the assembly of the pieces; these are then erased by rubbing with the fingers or using a tool.

    The coiling technique offers two main advantages as a manufacturing process: first, it guarantees a certain degree of uniformity in wall thickness, which allows for more even firing and increases strength and durability. Secondly, it allows the use of harder clays, as the material is not stretched as heavily as in other techniques such as modelling. Images 1, 2

  • Modelling

    This is one of the fundamental techniques used to make a ceramic vessel. It begins with a lump of clay, into which the potter presses his thumb to make a cavity; the cavity is then enlarged and the walls made thinner by hand as the larger vessel takes shape. This technique is best suited for making small bowls or the base of larger pieces that are then completed using other techniques. Very malleable clays must be used so that the walls can be stretched out to the desired size and thickness. Images 1, 2

    Modelling was also used to make the human-shaped figurines found at both New and the Old World archaeological sites. Some figurines made by the Valdivia culture on the coast of Ecuador were modelled using dark brown and grey clay. The body and limbs were modelled from a solid lump of clay, which was attached to another lump representing the head. The nose was formed directly on the figure, while the eyes and mouth were attached later using a technique called appliqué, whereby small pieces of clay are attached to the outside of a larger piece. The exaggerated stomach, one of the key characteristics of these figurines, was also added afterwards, using a sphere of material with two smaller pieces of clay to represent the breasts. These were attached to the already-formed body then the joins were smoothed over to make them flat. A sharp instrument was then used to incise details such as lines on the forehead and face. Image 3

    The same technique was also used to achieve very complex forms. The Moche people of Northern Peru used modelling to make pieces in the shapes of animals with human faces that also incorporated an unusual feature: a stirrup-shaped handle. It is not known exactly how these handles were made, but they were probably rolled up sheets of clay attached the ends to the figure. Images 4, 5

  • Moulding

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    Moulding consists of pressing portions of clay into or onto a pre-prepared mould that could be made of stone, plaster, or ceramic. Broken ceramic vessels were also used. These moulds could be convex, in which case the clay is applied to the outside, or concave, where clay is applied to the inside. A single vessel could be made from a single mould or from several; in the latter case, the joints can normally be seen on the inside of the vessels. Sand, ash, powdered ceramic, or other substances could be be used to prevent the clay from sticking to the mould. Moulds are used to produce highly standardized pieces, making it very effective for large-scale production. Moulds are best suited for making closed shapes such as bottles, which are hard to work from the inside as they have a very narrow neck. Images 1, 2

    The technique of moulding was used extensively in two areas of the pre-Columbian Americas: Mesoamerica and the Central Andes. In both areas the technique became more highly developed and sophisticated over time and was used to produce complex ceramic pieces. An example of this type of craftsmanship is found in the Chimú culture of Northern Peru, whose potters were highly skilled in the production of moulded ceramic figures, producing a wide variety of human, animal, and plant shapes. Concave two-part moulds were most popular. These had the form of the design in their interior, with the desired textures already applied. When the clay forms were removed from inside the moulds, they were already decorated and ready for surface polishing. Images 3, 4.

  • Surface finishes

    Different techniques can be used to finish ceramic pieces. One of the simplest is smoothing, whereby the surface is made even and excess clay is removed using a smooth stone, leather, spatula, or cloth. Depending on the smoothness of the tool and the force applied to the clay surface before firing, different finishes can be obtained: smooth, polished, or burnished. For an even, fine finish, all extraneous material must be removed from the surface. For a better quality finish and more uniform colour, a thin layer of liquid paint or diluted clay (slip)is applied by immersion. When clay slip is used, this technique is known as engobe. Other decorative techniques such as painting and appliqué can be added afterwards, either before or after firing.

  • References

    • ARNOLD, D., 1985. Ceramic Theory and Cultural Process. New Studies in Archaeology. Cambridge: Cambridge University Press.
    • CASTRO, V. & V. VARELA, 1990. Artífices del barro. Santiago: Museo Chileno de Arte Precolombino.
    • DAMP, J. & P. VARGAS, 1995. The Many Contexts of Early Valdivia Ceramics. En The Emergence of Pottery: Technology and Innovation in Ancient Societies, W. K. Barnett & J. W. Hoopes, Eds., pp. 157-168. Washington D.C.: Smithsonian Institution Press.
    • LEROI-GOURHAN, A., 1967. Prehistoria del arte occidental. Barcelona: Editorial Gustavo Gili.
    • OSBORN, A., 1979. La cerámica de los Tunebos. Un estudio etnográfico. Bogotá: Fundación de Investigaciones Arqueológicas Nacionales, Banco de la República.
    • RICE, P., 1987. Pottery Analysis. A Sourcebook. Chicago: University of Chicago Press.
    • 1999. On the Origins of Pottery. Journal of Archaeological Method and Theory 6 (1): 1-54.
    • SERRANO, A., 1978. La cerámica indígena. Tercera edición. Córdoba: Editorial Assandri.
    • SHEPARD, A., 1956. Ceramics for the Archaeologist. Washington D. C.: Carnegie Institute of Washington.
    • SHIMADA, I., 1994. Tecnología y organización de la producción de cerámica prehispánica en los Andes. Lima: Fondo Editorial, Pontificia Universidad Católica del Perú.
    • SINOPOLI, C., 1991. Approaches to Archaeological Ceramics. Nueva York: Plenum Press.
    • URIBE, M., 2004. Alfarería, arqueología y metodología. Aportes y proyecciones de los estudios cerámicos del Norte Grande de Chile. Tesis para optar al grado de Magíster en Arqueología, Universidad de Chile.