Are you able to tell the difference between porcelain and ceramic, or between fine china and bone china?
They can look very similar, but actually there is a distinct difference between them. I know that someone, even on websites, uses the terms interchangeably, claiming that they all mean the same thing. This is not true. In fact, for example, porcelain is a type of ceramic, while not all ceramic is porcelain.
Ceramic, pottery, earthenware, terracotta, stoneware, porcelain, fine china, bone china, paper clay are various types of clay bodies, and each one has its own unique characteristics and uses.
Ceramic is a general term that describes any article made of natural clay, mixed in various formulas with water and sometimes organic materials, shaped, decorated, usually glazed, and hardened by heat.
The composition of the clays used, type of additives, firing temperature and duration determine the quality and the hardness of the end product. Because these variables can be widely adjusted, there are many different types of ceramic.
Therefore ceramic is a broad category that includes pottery, earthenware, terracotta, stoneware, porcelain, fine china, bone china, paper clay, etc. as subcategories.
Boule by Kose Milano
Technically speaking, ceramics and pottery are the same thing because they are made in the same way through a process of shaping, firing, glazing, and re-firing. However the two terms have different subtleties in their meanings.
The word ceramics is a more general term that includes pottery, but also ceramic inlay for teeth, ceramic knifes, ceramic tiles, etc. In the context of art, ceramics are frequently thought of as higher-end professional-grade work that produces pieces of fine art with a decorative value (as clay sculptures or decorative plates).
Pottery can still be considered fine art in some cases, but commonly describes less sophisticated, functional clay objects that serve a purpose in daily life (as plates, cups or vases).
Stoneware mugs collection by Mette Duedahl
Earthenware is the earliest type of pottery. It is made from either red or white clay baked at low temperature, typically 1000-1080°C (1830-1980°F). Since it has not been fired to the point of vitrification, earthenware is porous and must be glazed in order to be watertight. It is generally more fragile than other types of pottery.
Earthenware vase by Sheldon Kaganoff
Terracotta (“baked dirt” from the Latin “terra cotta”) is a type of red earthenware usually unglazed. The typical firing temperature is around 1000°C. The iron content gives the fired body a brownish color, which varies considerably being yellow, orange, red, “terracotta”, pink, grey or brown.
Rosae, limited edition terracotta vase by Paolo Ulian
Stoneware is composed of fire clay and ball clay as well as feldspar and silica. It is fired at high temperatures, typically 1148-1316°C (2100-2400°F), and is inherently non-porous. The white, gray or brown clay vitrifies during firing, so the surface will be watertight. Stoneware can be left unglazed and still be usable for holding water, but it is more usual to glaze the inside of the vessel, at least.
Stoneware is harder, stronger and more durable than earthenware.
Stoneware bowls by Norman Yap
Porcelain is a white clay body used in making functional and non-functional pieces. Basically, the chemical composition of porcelain is a combination of clay, kaolin (a primary clay known for its translucency), feldspar, silica and quartz, but other materials may be added.
It is traditionally fired at high fire temperatures above 1260°C (2300°F). As with stoneware, the body vitrifies during firing, so the surface will be nonabsorbent. The surface is generally very smooth, even when unglazed, and the fineness of the clay used allows for intricate fine details.
The most significant identifying factor for porcelain is its translucence. Porcelain after firing becomes very white and translucent, allowing light to show through it. All other ceramics are opaque and do not transmit light.
Another identifying factor is the sound. If you strike a porcelain object lightly, it will ring with a clear bell-like sound.
Porcelain is a highly durable and hard material.
Paper-thin bowls in porcelain from Limoges by Arnold Annen.
China vs Porcelain
Due to many difficulties of working with porcelain, several imitations have been developed. These are referred to as china, fine china, bone china, and sometimes erroneously as porcelain.
The fine china is fired at a lower temperature – around 1,200° (2,200° F). Fine china is much softer than porcelain, making it much more suitable for applications such as plates and cups.
Bone china is a type of soft-paste porcelain made white and translucent by the addition of calcined animal bone to the body. The quality of the finished product is based on how much bone is in the mixture: a high-quality bone china should contain 30 to 40–45 percent bone.
Bone gives the fired body high levels of translucency and a unique milky white color.
Bone china cannot be fired at the same high temperatures as porcelain.
Bone china has very high mechanical strength and chip resistance that allow to produce thinner objects, unlike other types of porcelain.
Bowls and spoons in bone china by Caroline Swift
Paper clay is any clay body to which processed cellulose fiber (paper or cardboard being the most common) has been added.
Cartocci in porcelain paper clay by Paola Paronetto
Image credits: Featured image