Category: Materials and Techniques

Pottery is one of the oldest and most popular forms of decorative art, mainly made with clay. Ancient civilizations already used pottery as recipients for water or food. A peculiar method is the Japanese Kintsugi where gold is used to repair broken object giving them new life.

What is pottery?

The word pottery indicates objects made of clay that have been modeled into the desired shape, dried, and either fired or baked to maintain their form. It is the first synthetic material ever created by humans. In archaeological sites, the prevalent kind of item found is pottery that has been very important in understanding the human past and society’s development. Clay is abundant, affordable, and versatile, which makes it suitable for many applications. There isn’t solid evidence of a causal correlation between a sedentary way of life and pottery-making. However, the introduction of pottery generally corresponds with the switch to an agricultural lifestyle, when long-lasting and sturdy vessels and containers are necessary.

History of pottery

The earliest recorded evidence of clay usage dates back to the Late Palaeolithic period in central and western Europe, where clay statuettes were created as a form of artistic representation. The oldest evidence of pottery manufacture has been found at the archaeological site of Odai Yamamoto, in Japan, where bits from a particular vessel have been dated to about 16,500-14,920 years ago. Initially, pottery was made in open fires. However, during the Early Neolithic era, around 8,000 BCE, special ovens used to desiccate cereal grains and bake bread were being built in the Near East. This development allowed people to manage fire and generate high temperatures in enclosed spaces. The use of ovens added new opportunities to the development of pottery.

In the past, people would carry water in handwoven containers. The water, especially that from rivers, would contain some clay in it. As the water evaporated, the clay would take on the shape of the basket. Eventually, people understood that these clay linings could be used as containers. They collected clay, cast it, and let it dry in the sun or hot ashes, sometimes embellishing them with archaic tools. Therefore, the first clay pots were created. One of the believed origins of the first potter’s wheel might is from Sumer in 3129 BC. Antecedents to the wheel started appearing as early as 4500 BC, so it is impossible to have an exact date. The ancient Greeks were also famous for their pottery, particularly their vases. These pieces were frequently decorated with stories of mythological heroes and the Greek pantheon. Nowadays, pottery is heated by the use of a kiln. Probably the first civilization that invented the kiln is ancient Egyptians. It was lined with clay bricks and straw for insulation. 

Shaping techniques

There are many ways of shaping pottery, the most relevant are:

1. Hand modelling: the earliest vessels were modelled by hand using the same technique that the Japanese still use to make raku tea bowls. They applied flat slabs of clay luted together to create a square so that later these slabs could become a cylinder and put on top of a flat base created using the same method.
2. Coiled pottery: Long rolls of clay were twisted in a circle and put on top of each other until they reached the desired form. The sides of the vase (internally and externally) were then finished by smoothing and scraping.
3. Potter’s wheel: it is still impossible to precisely determine when the potter’s wheel was introduced. We know for sure that it was introduced to ease the turning motion needed to create the vessels. The potter puts the clay onto a rapidly turning disc that he then models by using both hands to ensure greater symmetry and precision.
4. Jollying, or jiggering: is the industrial adaptation of wheel throwing and it’s used when duplication and mass production is required. The head of the machine consists of a plaster mould that is shaped like the inside of the desired object while the exterior is modelled by a profile that comes into contact with the clay. 
5. Moulding: it’s one of the first methods of shaping clay. The first pots were created by putting clay around the inside of a container. Around 1745, in the Staffordshire region, were introduced the Plaster of Paris moulds. These plasters made it possible for the vessels to be cast in slips so that when the slip was poured into the mould the plaster absorbed the water, leaving a layer of clay on the surface of the mould. When this layer is thick enough the surplus gets cut off, the cast removed so that the mould could be used again. This method is still very commonly employed.

Types of pottery

• Earthenware was the earliest type of pottery made, dating back about 9,000 years and it is still widely used. The earthenware body varies in color from beige to dark red and from grey to black. The body can be covered or decorated with slip (a cream-like mixture of clay and water used for adhesive and casting or decoration), with a transparent or opaque tin glaze. Tin-glazed earthenware is normally called majolica, faience, or delft. 

• Stoneware
• is extremely strong and can be translucent or opaque. The color of the body varies considerably; it can be red, brown, grey, white, or black.

• Porcelain was originally made in China during the Tang dynasty (618–907 CE). It was produced from kaolin (white china clay) and petuntse (a feldspathic rock also called china stone) made into powder and mixed with the clay.

Decorating techniques

• • Painting: it is often applied to pottery that has been already fired. 

• Glaze: it also works as protection to the pottery keeping liquid from penetrating the pottery. Glaze can be clear, particularly overpainting, coloured or opaque. 
• Carving: vessels can be decorated by a simple carving of the clay body, typically with a knife or similar tool used on the wheel. This is popular in Chinese porcelain.
• Burnishing: this method consists of burnishing the surface of pottery objects before firing by rubbing with a proper instrument of wood, steel or stone to produce a polished finish that survives firing. 
• Additives can be worked into the clay body before forming, to produce desired effects in the fired wares. Coarse additives such as sand and grog are sometimes used to give the final product a particular texture. Other types of additives are colourants like metal oxides and carbonates, and combustible particles mixed with the body or pressed into the surface to produce texture.
• Lithography: also called litho, transfer print or “decal“. It is used to apply designs. This method requires three layers: the color, or image, layer which contains the decorative design; the cover coat as a clear protective layer; and the backing paper on which the design is printed. 
• Banding is the application by hand or by a machine of a band of color to the edge of a plate or cup. Also known as “lining”, this operation is often carried out on a potter’s wheel.
• Agateware: it resembles the quartz mineral agate. Agatewares are made by blending clays of different colours but not mixing them. The objects have a distinctive veined look. In this case, the clays used must have matching thermal movement characteristics to ensure structural stability.
• Engobe: it is a clay slip used to coat the surface of pottery, usually before firing. Its purpose is often decorative or to mask undesirable features in the clay. Engobe slip can be applied by painting or by dipping to provide a smooth coating. Engobe is sometimes combined with sgraffito decoration, where a layer of engobe is scratched through to reveal the color of the underlying clay. 
• Gold: this type of decoration is used on some high-quality ware. Different methods exist for its application, including best gold, acid gold, bright gold, mussel gold. Japanese Kintsugi method (golden repair) is used to repair broken pieces of pottery giving them new life and adding value.

Info sources: https://www.britannica.com/art/pottery
https://www.tomorrowsworldtoday.com/2018/08/01/a-brief-history-of-pottery/
https://www.ancient.eu/pottery/
https://ceramics.org/about/what-are-engineered-ceramics-and-glass/brief-history-of-ceramics-and-glass
https://en.wikipedia.org/wiki/Pottery