It is made of a special clay that is baked in an oven. Then u put over it the color (where you don't put color will become black). Then again it goes in an oven till about 1050 Celsius. When you get it out it goes in a bin with woodcurls where it stays 20 minutes. Then it goes in water to cool it down suddenly which gives the cracks. Then you have to clean it and "klaar is Kees"