Why Is Pottery Called Ceramic?
Ceramics, also commonly known as pottery, refers to items made from clay that are fired in a kiln to harden them. The term “ceramic” encompasses a wide range of clay-based products, ranging from building materials like bricks to decorative items like vases and figurines. In this article, we will explore the history and origins behind the term “ceramic” – where it came from and how it came to refer broadly to fired clay objects.
Definition of Ceramic
Ceramic refers to objects made from inorganic, non-metallic materials that require heat to become solid. Ceramics are compounds formed between metallic and non-metallic elements. Ceramic materials are brittle, hard, strong in compression, and weak in shearing and tension. They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments. Ceramics generally can withstand very high temperatures, ranging from 1,000 °C to 1,600 °C (1,800 °F to 3,000 °F).
History of Ceramics
Pottery dates back over 20,000 years. Early pottery was made from clay and hardened by sun-drying or low-temperature firing. The oldest known ceramic artifact is the Venus of Dolní Věstonice figurine, discovered in the Czech Republic and dated to 29,000–25,000 BC.History of pottery at a glance – Universe of Ceramics Pottery was independently developed in many regions of the world. In East Asia, early pottery was developed in China, Vietnam, Japan and Korea. The earliest ceramics known in the Sinosphere date back to 18,000-17,000 years ago during the Late Paleolithic period.The origin of ancient pottery production In the Americas, pottery was developed around 4,000-3,500 BC by early Native American cultures.
Etymology of Ceramic
The word “ceramic” comes from the Greek word “keramikos” meaning pottery, potter’s clay, or porcelain. It is related to the older Indo-European root “ker-“, meaning to burn or fire [1].
The word “keramikos” comes from “keramos” which meant potter’s earth or tile in Greek. This is derived from the Proto-Indo-European root “ker-” referring to burning or fire, which is fitting as firing clay at high temperatures is an essential part of pottery and ceramic production [2].
The Greek root “keram-” referred specifically to pottery clay that was worked into vessels and objects, differentiated from other clays and soils. Over time, the meaning broadened to refer to any products made from this clay material that were fired and glazed, including pottery, porcelain, and other ceramic wares.
So in summary, “ceramic” etymologically traces its origins back to Greek words referring to the special clay used for pottery and the burning process used to harden and finish ceramic objects. This is why the term “ceramic” became closely associated with pottery and clay products.
Types of Ceramics
There are several main categories of ceramic materials, each with different properties and characteristics:
Earthenware
Earthenware is a common type of ceramic made from clay and fired at lower temperatures up to around 2,200°F. It is porous and less durable than other types of ceramics. Common examples include terra cotta pottery and flower pots (Source).
Stoneware
Stoneware is fired at higher temperatures between 2,200-2,400°F making it denser and more durable than earthenware. It is non-porous and water-resistant. Common examples include tableware, cookware, and art pottery (Source).
Porcelain
Porcelain is fired at very high temperatures above 2,400°F and is highlyvitrified making it strong, hard, and non-porous. It is commonly used for tableware, sanitaryware, electrical insulators and more. Porcelain has a bright white color when pure (Source).
Bone China
Bone china contains bone ash as an ingredient, making it very white and translucent after firing at high temperatures above 2,240°F. It is known for its high strength and chip resistance despite its delicate appearance (Source).
Ceramic Production Process
Ceramics are created through a multi-step process that transforms raw clay or powdered ceramic materials into a finished ceramic product. Here are the basic steps:
Preparing the Clay – Raw clays are refined and blended to achieve the desired properties. The clay is then mixed with water to make it plastic and workable.
Forming Shapes – Pottery wheels, molds, extruders, and presses are used to form the wet clay into the desired shape. Common forming techniques include throwing, slip casting, pressing, and extrusion. (https://www.sentrotech.com/the-ceramics-manufacturing-process/)
Drying – The shaped clay objects are left to air dry until most of the water evaporates and the clay becomes strong enough to handle without deformation.
Firing – The dried pieces, called greenware at this stage, are fired in a kiln at high temperatures. Firing fuses the clay particles and permanently hardens the ceramic. Typical firing temperatures range from 600°C to over 1400°C depending on the type of clay and desired properties. (https://www3.epa.gov/ttnchie1/ap42/ch11/final/c11s07.pdf)
Glazing – Glazes made of minerals mixed with water are applied to ceramics before the second firing to create a decorative, impermeable surface. The glaze melts and fuses to the body during kiln firing.
Additional Machining – Some ceramic products may require additional machining, drilling, or finishing after firing.
Characteristics of Ceramics
Ceramics are known for their unique properties that make them useful across many applications. Some key characteristics of ceramic materials include:
- Hardness – Ceramics are extremely hard, rigid, and durable materials. For example, alumina ceramics have a hardness of 9 on the Mohs scale, making them highly scratch and abrasion resistant. The strong bonds between atoms resist deformation under force.
- Brittleness – While hard, ceramics are also quite brittle and prone to fracture when stressed, especially under tensile or bending loads. They lack the ability to deform plastically. Ceramics do not exhibit yield behavior typical of metals.
- High melting point – Many ceramics have very high melting temperatures exceeding 1000°C or more. This gives them good high temperature properties and resistance to creep and distortion.
- Low thermal conductivity – Ceramics are generally poor conductors of heat, making them good insulators. This property is useful for applications like ceramic cookware.
- Corrosion resistance – The stable atomic structure of ceramic materials makes them chemically inert and resistant to corrosion in many environments.
- Electrical properties – Some ceramics exhibit piezoelectricity, ferroelectricity, and can be made magnetic. Their electrical properties enable applications in sensors and electronics.
By understanding these unique characteristics, ceramics can be designed and implemented in applications that take advantage of their specific properties.
Uses of Ceramics
Ceramics are used in a wide variety of applications due to their versatile properties. Some of the most common uses of ceramic materials include:
Pottery – Ceramic materials like clay, porcelain, and stoneware are used to create pottery items like vases, plates, bowls, and decorative pieces. Pottery is one of the oldest uses of ceramics, dating back thousands of years.
Tiles – Ceramic tiles made of clay or porcelain are a popular flooring and wall covering option. They are water resistant, durable, and available in a huge range of colors, shapes, and patterns.
Bricks – Bricks used in construction are most commonly made from clay ceramics, which can withstand high temperatures during firing. Ceramic bricks last a long time and have good insulating properties.
Insulators – Certain ceramics like porcelain and mica have very low electrical and thermal conductivity, making them useful as insulators in power transmission lines and appliances. Their high heat resistance also suits them for insulation.
Semiconductors – Many ceramics exhibit semiconducting properties, meaning their conductivity lies between that of conductors and insulators. Semiconducting ceramics like silicon carbide and gallium nitride are used to make electronics like transistors and LEDs.
Abrasives – Very hard ceramics like alumina, silicon carbide, and boron carbide are manufactured into abrasive powders and grains for applications like grinding, polishing, and sandblasting.
Bioceramics – Calcium and aluminum phosphates are used to make bioceramics for medical implants and devices. Their compatibility with biological tissues makes them useful for applications like bone repair and tooth implants.
High-temperature ceramics – Ceramics like silicon carbide, silicon nitride, and zirconium oxide retain strength at very high temperatures, so they are used for automotive engine components, gas turbines, and other heat resistant applications.
The versatile properties of ceramics including high hardness, heat and corrosion resistance, electrical properties, and bio-compatibility enable them to be used in this wide array of products that we use every day.
Ceramics vs. Pottery
Pottery is a type of ceramic, but ceramics encompass a broader range of clay-based items. While all pottery can be classified as ceramic, not all ceramics are considered pottery.
Ceramics refer to any items made from nonmetallic mineral materials that have been hardened by heat. This includes pottery, but also includes ceramic tiles, dishes, figurines, and many other items.[1]
Pottery specifically refers to functional or decorative vessels, sculptures, and tableware made from clay and fired in a kiln. It is a subset of ceramics focused on clay-based objects like pots, vases, plates, and bowls.[2]
The key difference is that pottery must be made from clay, whereas ceramics can include other nonmetallic minerals like quartz. Additionally, pottery refers to objects made for a specific purpose, while ceramics can refer to any fired clay item including artistic, decorative, or conceptual pieces.
So in summary, all pottery is ceramic because it is made from clay and fired. But not all ceramics are considered pottery, since the term pottery is limited to clay-based vessels, dishware, and sculpture.
[1] https://www.classpop.com/magazine/ceramics-vs-pottery
[2] https://thepotterywheel.com/what-is-the-difference-between-ceramics-and-pottery/
Conclusion
Pottery and ceramic are synonymous terms with a long, intertwined history. Ceramics refers to objects made from inorganic, non-metallic materials that require firing at high temperatures to achieve their desired properties. Clay is the most common ceramic material and has been used to create pottery and other objects for thousands of years across human civilizations.
The word “ceramic” comes from the Greek word keramikos, meaning “potter’s clay.” This etymology reveals that ceramics and pottery are linguistically linked. Pottery is considered a ceramic because it is made from clay and undergoes high temperature firing to permanently harden it. While some ceramic materials like bricks and tiles may have structural differences from pottery, they share the same production process and material composition.
Throughout history, pottery and ceramic vessels were vital for storage, cooking, religious rituals, art, and more. Clay was an abundant, malleable material that allowed ancient civilizations to create a diverse array of functional and decorative objects that were impervious to water and able to withstand high temperatures. The ubiquity of pottery across human cultures is why the terms ceramic and pottery are used interchangeably today.
In summary, pottery earned the designation of ceramic because it represented one of the first and most widespread applications of ceramic material. The similarities in their production and composition over thousands of years led to pottery and ceramics becoming synonymous. While ceramics have expanded to include many non-clay substances today, the long history and importance of pottery means that it remains exemplary of ceramic objects.
