For thousands of years even before people settled down, ceramics were already an integral part of their lives. It revolutionized cooking and eating, food storage, craftsmanship and construction. And it made things possible that we now take for granted. It was a long way, lined with numerous discoveries and inventions, to the high-quality pottery we now know. And even today, fired earth is as simple as it is ingenious.
Silent witnesses of mankind
The term ceramics comes from the ancient Greek word keramos, which describes both the clay and the products made and fired from it. It is not clear how long humans have been making pottery. However, the oldest relics found so far are about 25.000 years old.
One of the oldest surviving ceramic pieces is the Venus of Dolní Věstonice, a figurine about eleven centimeters tall that archaeologists came across during excavations in what is now the Czech Republic. To avoid shrinkage cracks, animal bone meal was added to the raw material from which the figurine was formed. The creator of the figurine is unknown. However, a fingerprint can be seen on the back, which, according to scientific analyses, is attributed to a girl around 11 to 14 years old.
Invention or discovery of ceramics
Most probably, ceramics were not invented, but rather discovered - independently in different parts of the world. Clay slabs were often used as a base for a fire, which hardened and became water-resistant due to the heat. This discovery is thought to have inspired humans to create building materials, handicrafts, and vessels such as cookware and tableware. An important advantage of ceramic containers compared to the baskets and fur bags previously used was the better shelf life of the food. Therefore, pottery also simplified food storage.
The revolution of the potter's wheel
It was not until many thousands of years later that traditional pottery as we know it today came about with the use of the first potter's wheel. The oldest known wheel comes from Mesopotamia and is dated 3.000 BC. The invention is therefore often attributed to the Sumerians. Findings of various fragments, however, suggest that vessels may already have been thrown on potter's wheels in India 2.000 years earlier. The exact period of this important invention can therefore not be precisely documented. What is certain is that the wheel made it possible to work faster and more precisely.
Photo (C) Paulo Castro Photography
From clay to ceramics
Early pottery was probably fired in normal outdoor fires and with firewood, and was therefore far less durable than today's pieces. Still, the comparatively low temperature were sufficient to dry the clay and make it almost waterproof, which made the material very versatile.
Burning goods in earth-pits already allowed for higher temperatures. Large pits were dug in the ground for that purpose and first preheated with a fire, while the unfired pottery was gradually moved to the center. The products remained in an open fire for several hours. The pit was then covered with brushwood, sawdust or straw and hermetically sealed with earth. There the pieces were fired for another 12 to 16 hours until the pit was opened and the pottery was exposed.
The first kilns
The first ceramic kilns have been archaeologically documented in south-eastern Europe since the Middle Neolithic (~6.000 BC). These were single-chamber kilns in which both the goods and the fuel were burned together in a common chamber or under a kiln dome.
Around 2.000 years later, pottery kilns with separate chambers for goods and firing material emerged in the Middle East. The pottery was placed on a perforated floor above the firebox. They were therefore only exposed to the hot smoke gases and not to the direct fire.
A few decades BC, people were already working with kiln that could keep a relatively constant temperature of 950°C. During this time, the first ceramic manufactories emerged, which produced pottery in an industrial sense.
The progression from standing kilns with rising flames to horizontal kilns, which made better use of the flames, allowed more constant firing temperatures. The heat from the fire was drawn from the combustion chamber through a chimney. With this method, a massive increase in quality could be achieved, which ultimately led to the invention of stoneware, the first fully sintered ceramic.
The triumph of sintered goods
From a firing temperature of ~1.150°C, a process called sintering begins. This means the fusion of the crystals on the surface of the clay to form a glass-like layer. This process ensures that the ceramic is particularly resistant to impact and - even when unglazed - absorbs almost no water. In contrast to the porous earthenware, which also includes terracotta, stoneware is therefore much more suitable for everyday use and more resistant.
Achieving this level of quality not only required ingeniously designed kilns that reached temperatures above the sintering limit, it also required a less fatty clay with a higher proportion of silicate crystals. However, the development of ceramics in Europe was strongly influenced by the Middle East, which only had clay suitable for lower temperatures. While stoneware was not produced in the western hemisphere until around 1.300 AD, this was done in China around 500 years earlier.
The white gold
Starting in China, hard porcelain, which - like stoneware - belongs to the class of sintered goods, also conquered the European continent from the 14th century. From around the time of Christ's Birth, experiments were being carried out with the composition of the clay, containing kaolin, which is a crucial ingredient for porcelain. Nevertheless, it took several centuries until the right composition was found and the high temperatures of up to 1.500°C were reached. The result is particularly hard, dense and slightly translucent. Porcelain is naturally very light, which is why it is usually only covered with a transparent glaze.
At the beginning of the 18th century, the first European hard porcelain was produced in Germany. From this time onwards, porcelain manufactories began to appear near Dresden and in Vienna, and finally all over Europe.
Industrialization and mass production
The increasing industrialization in the 20th century also shaped the manufacture of ceramics and increasingly made them a mass product. Highly efficient kilns and machines now allow the production of large quantities that end up in the shops at low cost.
From the end of the 1970s, cheaply produced ceramics, especially from Asia, were brought onto the European market. Due to the high competitive pressure, many traditional manufacturers who could no longer bow to the dumping prices disappeared.
A slow trend reversal
In recent years, however, there has been a turnaround and a return to handmade and fair traded goods. This is not least due to the increased environmental awareness of our society, which no longer wants to accept long trade routes across continents. Also due to their quality and uniqueness, goods made from traditional craftsmanship are once again enjoying a higher reputation.
Photo (C) Paulo Castro Photography
This change of direction benefits us all. After all, one day we want to leave our grandchildren a livable earth. And maybe one or the other piece of our favorite ceramics.