CERAMIC MATERIALS

Clay, mud and water are the main materials used in ceramics to make the pieces. The word ceramics refers to the piece of clay once fired.

Clay is the result of the natural aging process of the Earth’s surface, the crust of which is made up of about 75% silica and alumina, the main oxides in the composition of clay. Since this aging process is continuous and occurs everywhere, clay is an extremely common and abundant material in nature.

The mixture of other components found in the earth produces different types of clay, varying in color, texture, physical and chemical properties and firing temperature. Some clays are named after their place of origin.

Being such an abundant material on the planet, we can find ceramic pieces in any corner of the world.

Few clays can be used as they are found in nature, they usually crack when modeled, except to make bricks, tiles, roof tiles and rustic “pots”, that is why from ancient times to the present day, the mixing of clays has been and is an almost universal practice.

A test that we can do to see if the clay is valid to work directly with it is to make a churro and bend it, depending on its plasticity it will crack more or less or nothing, of course, the better it resists torsion the more plastic and suitable to be modeled.

Knowing the different types of clays helps us to choose the most appropriate when creating.

What types of materials are most suitable for ceramics?

There is no more or less appropriate clay, there are incredible pieces modeled in the coarsest red clay as well as in the most delicate porcelain.

Choose the materials depending on the technique to be used:

Experimentation and personal work will lead us to find the ideal material for each creation. However, it is true that each clay is better suited to one style or another, so it will depend on the ceramic techniques used.

If I want to model a sculpture I prefer clay with chamotte, because it gives consistency to the clay when it is modeled and absorbs the possible stresses of drying and firing. The chamotte is ceramic ground to different granulometries that is added to the clay.

If I want to model small details, I personally like stoneware with impalpable chamotte.

For subtle and light pieces, porcelain, composed mainly of kaolin, reaches unequaled levels of transparency and delicacy. In tableware, we can use something more resistant such as ball clay.
With fire-fired burnished red clay we obtain a striking glossy black, etc.

Nowadays there is a great offer of clays and we do not limit ourselves to the local clay, if any, but we can try all kinds of muds.

 Choose the materials for ceramics according to the firing.

This is a very important detail.

The material to be used can be divided into high and low temperature clays.

• Low temperature would be those cooked in an approximate range of temperatures between 1800º F to 2020ºF. The best known are the ferruginous reds, the earthenware and white muds, and the terracottas.
• In the group of high-temperature clays that withstand firings above 2200º F are stoneware, porcelain and refractory clays, whose firing range is between 2200º-2400º F.

You can look in the clay section of the websites of online stores selling materials for ceramists and you can see in them the number of different clays they offer, as well as a detailed description of their main characteristics such as color, firing temperature, if it is used more for pottery, ceramic sculpture, artistic ceramics, ceramic murals, ceramic jewelry, hand modeling, for casting molds of handmade casting, etc..

For the type of work that I do, I feel comfortable with high temperature chamotte clay, this clay gives me a lot of freedom when modeling because it has a lot of consistency and the shapes that I create are maintained with a lot of security, especially when I build through spirals in the air without any support or mold.

On the other hand, in my pieces I use few glazes, I like rustic finishes with a natural look and the high temperatures help me to fix the oxides that I apply in the finishes.

In the ceramics classes I teach we use a greater diversity of materials to experiment with different proposals and techniques.

The contact with the mud is always rewarding, if you have never tried it I encourage you to take a piece and let yourself go.

Arantxa

Materials and ideas to start at home:

It is a widespread idea that to start trying pottery you need to have a kiln that reaches over a thousand degrees, a potter’s wheel, a thousand different instruments and tools, and so on. Well, there is a solution to this.

A very simple way to get started in modeling, start to feel the experience and get the hang of it is to start with some more modern materials that do not require the temperatures mentioned above (yes, in a way they would not qualify as ceramics in a technical sense but so what?).

However, this result will be just as worthy and the parts can also have great resistance.

This is the case, for example, of polymer clay, which with the firing temperature that our kitchen oven can give will be enough.

Another material to be used can be air-drying modeling paste, which, as its name indicates, does not require a kiln, and once dried, the pieces are very hard. The disadvantage of this material is that it cannot get wet, but for decorative purposes it is a great option to start with, also thinking of children.

There are more options, some of them you don’t even need to buy, you can make them yourself at home, such as cold porcelain.

Consult our guides on these subjects to get started.