Porcelain is a specific form of ceramic material originating from China. Porcelain has a smooth sheen and is partly translucent. Specific clay called kaolinite is used to create porcelain. Other material includes alabaster, ball clay, bone ash, feldspar, glass, quartz and steatite. Until the 17th century, porcelain was only made in China and thus became known as "fine china." Marco Polo coined the term "porcelain" from the Italian word for "cowry shell" due to the texture of the seashell.
Clay used in porcelain comes in two types: long and short, depending on the elasticity of the clay. Elasticity, also known as plasticity, is the amount of water needed to change solid clay into a more pliable form. Clay with high plasticity is known as long clay and is sticky. Short clay is lower in plasticity and is more solid and dry. Porcelain is mainly created using short clay. This clay wets quickly and becomes workable in a short amount of time, hence the term "short clay." The time frame that the clay is workable is also very short. Controlling the water content during formation is critical.
The oldest type of porcelain is known as true porcelain or hard-paste. Petuntse, also known as china stone, is used to create it when ground into a powder and mixed with kaolin. The mix of clay and ground glass creates the soft-paste type known as artificial porcelain more common to European pottery. Josiah Spode created bone china. He mixed bone ash from animal bones with traditional china clay used in other porcelain. For bone china to be considered as such, it must contain at least 25 percent bone ash.
The clay porcelain is created from is "fired," or hardened, from the pliable state to a solid form. The firing causes glass to form within the clay. The glass formation is due to high levels of silicate in the kaolinite clay. The minerals in porcelain are ground up into a powder and then mixed with the clay. A temperature over 1400 degrees Fahrenheit is required to solidify the mixed material. This creates the glazed porcelain. Unglazed porcelain has less silicate with a matte texture.
The material in porcelain is highly versatile. Resistant to electricity, heat and moisture, the materials used to make porcelain allow it to be formed into any shape required.