What is porcelain?

The main components of the PORCELAIN are kaolin, which is a kind of clay mainly composed of kaolinite. It is named after it was first discovered in Gaoling Village, northeast of Jingde Town, Jiangxi Province. It’s chemical experimental formula is Al203·2Si02·2H20, and the weight percentages are 39.50%, 46.54%, 13.96%. Pure kaolin is a dense or loose block with a white and light grey appearance. When it is contaminated by other impurities, it can be dark brown, pink, beige, etc., with a slippery feel. It is easy to knead into powder by hand. After calcination, the color is white and the refractoriness is high. It is an excellent raw material for porcelain. The so-called “ceramic” is a form of clay made of clay or other inorganic non-metallic materials and processed by moulding and sintering processes to decorate and protect the walls and floors of buildings. After drying, it is heated to a certain degree to harden it and it is no longer soluble in water.

Traditionally it was white, smooth, vitreous and fired very high (to cone 10 or higher which is 2300 F, 1280 C).

Kaolin is usually always present. It is a primary clay, meaning it is found in the area it was formed and has weathered only a little so there is less iron picked from the environment and the particle size is bigger. Kaolin is named after a hill where it was mined in China. It means “High Ridge”, Kao-Ling 高嶺. Porcelain was first made in China in the Tang Dynasty (618–906 AD). This is why it was often called “china” in the western world. The word comes from an Italian word for a cowrie seashell, porcellana. People had all sorts of ideas about what porcelain was made of and it was a secret in Europe. It was not until the 18th century that the kilns and recipes were worked out to produce it in area outside of China. The story of it’s European discovery is a really great one full of trickery and death. Until that point it was a luxury trade good only available to the most wealthy in Europe. It was mentioned in the wills of Kings. That status continued up into the end of the 19th century. It hangs on as a special and somehow different substance in the popular imagination to this day. It is however just a kind of pottery clay. There are recipes for all sorts of temperature firing, for different purposes and characteristics, translucence or not and even different colors.

The three parts in a general clay body recipe work like this.

Silica (quartz): It provides an aggregate framework for the fired matrix (like gravel in concrete).

Clay: Imparts plasticity and drying hardness to the wet materials, and transforms into a mesh of crystals during firing (which gives porcelain its strength).

Feldspar and Nepheline Syenite: The melting of the feldspar fills, the voids between the silica and clay particles and cements them into a strong mass.

When porcelain is fired the feldspar creates a liquid phase in which some of the

kaolin (and quartz) dissolve, but also in which the kaolin crystal transforms into another form of different shape, mineralogy, and higher melting temperature. This crystal-matrix bonded by feldspar-glass on a silica-skeleton creates the hardness and toughness that porcelain can have.

This news from MagnobleTableware.