The classical production of charcoal consists of an extensive manual work.
First, a hill-shaped mass of oak branches is formed. Secondly, it is covered with green leaves and earth. Then, the center is burnt and the fire spreads slowly to other parts.
Charcoal workers maintain that the fire with limited oxygene inside the hill continues for about a week, during which oak branches turn into charcoal at a temperature of 250 to 300 degrees celcius.
In so doing, they often have to climb over this delicate hill with ladders to keep its form and fill-out its cavities.