Whilst developing the Made in Bow project we thought we’d share some information we found useful. Below is a list of relevent terms and processes.
Porcelain is a ceramic material made by heating a mix of raw materials. These materials usually include clay in the form of kaolin and are heated in a kiln to temperatures between 1,200 °C and 1,400 °C.
At these high temperatures glass and a mineral called mullite form within the mixture of materials, and this is what gives porcelain the characteristics it is known for- toughness, strength, and translucence.
The mix of materials used to make porcelain can vary a lot, but the clay mineral kaolinite is often one of these raw materials. Other raw materials can include feldspar, ball clay, glass, bone ash, steatite, quartz, petuntse and alabaster.
The word ‘paste’ is an old term for both unfired and fired material. A more common terminology these days for unfired material is “body” For example when a potter is buying materials they might order an amount of porcelain ‘body’ from a seller.
Clays used for ceramics are often described as being long or short, depending on their plasticity (how much they bend). Long clays are cohesive (sticky) and have high plasticity; short clays are less cohesive and have lower plasticity.
Clays used for porcelain are generally of lower plasticity and are shorter than many other pottery clays. They wet very quickly. This means that the nature of the clay will change hugley by adding only a small amount of water, and it is difficult to keep the amount of water in the mix constant. Whilst clay is stored, thrown (on a potter’s wheel) or formed (shaped) the moisture content must be carefully controlled to stop the clay from becoming too wet or too dry to manipulate.
Kaolinite is a clay mineral. It is a layered silicate mineral. Rocks that are rich in kaolinite are known as kaolin or china clay.
The name is derived from Kao-ling (Chinese: 高岭/高嶺; pinyin: Gaoling), a village near Jingdezhen, Jiangxi province, China.
As far as we know the first patent for Bone China was registered in 1744 by ‘Edward Heylin in the parish of Bow in the county of Middlesex, merchant, and Thomas Frye of the parish of West Ham in the county of Essex, painter.’
The correct recipe for bone china was being developed in England to compete with imported porcelain from China. Bone china is now made worldwide.
Traditionally English bone china was made from two parts of bone-ash, one part of kaolin clay and one part china stone.
Production of Bow Porcelain
Heylin and Frye did not have a factory of their own and carried out experiments with a skilled workman in a factory in Bow. Although Messrs. Crowther and Weatherby owned the first porcelain factory in Bow, Thomas Frye acted as the manager. These works were known as ‘New Canton,’ (Canton is a province in southern China) and though situated on the Essex side of the River Lea, close to Bow Bridge, were known as the Bow China Works.
At its highest point of success in 1758 three hundred people were employed in the factory, including ninety painters, all living under one roof. An account of the business returns for a period of five years shows that profits increased steadily from year to year, and had reached £11,229 in 1755.