Ceramics is the work of clay, of earth, shaped by turning, shaped, cast in a mould, to make it useful or decorative. The earth is also the earth, the one that carries and nourishes us. Then ecological ceramics or eco-friendly ceramic sounds like an oxymoron. However, clay craftsmanship can be polluting if no precautions are taken.
The raw material
A ceramic object is made of clay and there is a panel of more than 3000 pieces of clay from all over the world that can be ordered (classified into three main categories: earthenware, stoneware or porcelain). The first concern of sustainable production is, with similar characteristics, to select the most local land possible in order to limit the polluting impact of transport.
The earth has the particularity of being a material that is never waste. It can be handled, dried, re-wetted to become soil or transformed for another use. Thus, there is always a way to reuse surplus land so that it is not thrown away.
Firing into a kiln
There are different types of ceramic cooking methods: wood, electric or gas cooking. Each of these solutions has its advantages and disadvantages and the choice of a cooking method is generally made mainly according to the desired effects and the production method of the craftsman.
The most energy-efficient cooking methods are those with a wood fire, the most famous of which is the Raku. However, this technique requires an external space that not all ceramists have. This cooking technique is mainly used when trying to obtain its own particular cracking effect.
Another possible cooking method is in the electric oven. The parts are baked twice in an oven equipped with baking curves, in other words programs that limit energy loss. Manufacturers are constantly innovating with furnaces that are less and less energy consuming and better insulated to reduce energy losses. An ecological solution is to combine this furnace with green electricity consumption.
The last possibility is gas cooking, which requires constant monitoring of the cooking process and is quite restrictive. However, gas cooking, like wood cooking, makes it possible to cook in oxidation or reduction, and thus to obtain effects of colour and texture different from those obtained in an electric oven. It is also possible to use a green gas to limit its impact on the planet.
The question of the choice of soil according to its degree of cooking is debatable. Indeed, earthenware requires less cooking than stoneware and porcelain, so it consumes less energy. However, it is also less resistant and more porous. On the other hand, porcelain is the clay that requires the most energy during cooking, but it is also the most resistant once fired. A soil is chosen for its technicality, its colour, and its robustness.
There are different ways to colour a clay piece. A slip and/or enamel is generally used to form a vitrified layer to reinforce the part and ensure its non-porosity. They are both generally composed of oxides that are toxic and polluting when not cooked. For this reason, they must be placed in a settling tank and taken to the waste disposal centre to be treated in a compliant manner.
In addition, lead oxide, barium oxide or boron can be used in the manufacture of enamels. As a ceramist, it is important to be aware of the manufacturers’ specifications regarding the decorative or food use of an enamel. On a personal level, I will even limit their use entirely.
To conclude, there is no such label as Ecological Ceramics to my knowledge, it is more a question of the ceramist’s philosophy and ecological awareness. So the best solution is to start the conversation with him.