The kilns consist of a cylindrical body separated into three levels. The lowest is called the "first laboratoire" and is 2.6 m in diameter and 3 m tall. The middle level is called the "second laboratoire" and is 2.6 metres in diameter and 2 metres high. The top level is the 2-metre-high chimney cone. The firebox is an opening at the bottom of the first laboratoire, 1 metre high, 0.58 metres wide and 0.29 metres deep. In the vault between the first and second laboratoires, is a large flue at the centre and 9 small ones around the edge. These flues serve to guide the flames and release the heated gas. Grills, called "flue-guards" are arranged to divide the flames. At the base of the second laboratoire, a little fire box helps to increase the temperature further. The oven contains four fireboxes for distributing the heat effectively.