Kaolin is a weathering product of feldspathic rocks. It is invaluable to potters because it can withstand high temperatures without discolouring.
In glazes: Often used to introduce alumina Al2O3 and silica SiO2 into glazes. Increases the melting point, extends the melting interval, increases scratch hardness and chemical resistance, makes glazes more fluid and matt. Serves as a levelling agent, prevents the formation of crystals in the glaze slip, which is why it is also known as ‘floating clay’.
In masses: Main component of porcelain bodies.
In engobes: For the production of white engobes.