Clay is a very plastic material in its natural state and rigid after the firing phase.
With ceramics, decorative objects, building materials (bricks, tiles) coverings for walls and floors for homes are mainly reproduced.
It is a delicate material, not very suitable for frequent washing and not very resistant to shocks.
Once the clay piece has been modeled, it is dried perfectly and then subjected to the first firing which, depending on the clay used, varies from 950 ° C to 1000 ° C.
After the first firing the piece is called a biscuit, it is hard, resistant but still porous.
To make it waterproof it is subjected to enameling (by brush, spray or immersion) with neutral or colored enamel or crystalline and then cooked again for the second time.
The resulting piece will be impermeable to liquids.
Before the second firing, decorations with oxides can be carried out on the raw enamel (majolica technique).
All the phases of ceramic processing from modeling, drying, the first firing, glazing / decoration and finally the second firing have their own times and cannot be halved with shortcuts because all the errors then come out during firing.
There are different types of ceramics:
- porous-paste ceramics: terracotta, earthenware, majolica. They have a tender dough, more easily scratched.
- compact-paste ceramics: stoneware, porcelain. They have a very low porosity and good qualities of impermeability to gases and liquids. They are not even scratched by a steel point.