Has clay ground

Fireclay in the pottery


Fireclay is basically nothing more than clay that has already been fired and is then ground. Chamotte is offered in different granularities and is used in ceramics so that the clay mass does not contract too much and break while it dries and is fired.

In this article you will find out everything about chamotte in pottery: what the material is made of, what advantages the admixture of chamotte has in the clay mass and for which tasks you can use it.

What is chamotte made of

Fireclay consists largely of aluminum oxide and silicon dioxide, the main components of clay in addition to water and additives that have been added to the clay to change its color. In a nutshell, chamotte is a clay that has already been fired and is ground to different finishes.

The fineness of chamotte varies - it is comparable to the consistency of flour to fine sugar.

Benefits of chamotte

Chamotte increases the plasticity of the mass, so that it becomes more elastic and the tension of the mass decreases during drying. The plasticity of the clay is primarily determined by the particle size of the minerals, the water content and the age of the mass.

Another advantage of chamotte is the increased resistance when firing the ceramic. Fireclay ensures a smaller change in volume when firing and when cooling the mass in the kiln, so that it can withstand higher temperature fluctuations.

For example, in the raku firing process, a compound with a very high proportion of fireclay is required so that the ceramic can be heated and cooled very quickly without breaking.

Areas of application of chamotte

Since fireclay particles are much larger than unfired clay particles, ceramics with firebrick hold their shape better. This type of clay is therefore particularly recommended for modeling build-up techniques.

The use of chamotte is also a practical solution for recycling rejects. Fired objects that cracked during the fire are granulated and can be worked under again.