Charcoal pile

At the charcoal burning site, which is located where possible near a body of water so that it can be extinguished later, the wood pile is built in approximately hemispherical or conical piles, using short logs, mostly one-metre long, in even fashion (standing or lying down), around the central chimney (Quandel).

On top of this an airtight roof is constructed of dry fir branches, leaves, hay or straw, or alternatively of grass, vegetation and moss.

Finally the pile is sealed airtight with a mix of ash and charcoal pieces (possibly known as 'culm' or 'brusque'; German: Lösche, Stübbe, Stibbe or Gestübe) and earth, with the exception of the central chimney.

The wood must char, not burn, inside the pile; air being let in through the small holes so that no fire can start.

But it creates a lot of heat and the water evaporates, tar condenses on the green roof, the smoke is yellowish-white and odourless.

The air holes are now moved further down in order to also draw the fire into the lower areas of the kiln.

Each time the draft holes are moved, the smoke colour changes, the kiln charred from top to bottom.

Once charring is complete, the fire in the pile is quickly extinguished by the clogging of the air holes.

Now the cover is opened and then the coal is pulled out with a rake, fork or shovel and spread out to cool down.

If this is not done properly, the charcoal that has been produced burns within a very short time under great heat (exothermic reaction).

If tar extraction was to be combined with the charring of the pile, small pits were made in the ground or the ground was lined with clay and the tar led out of the pile by means of a channel, and the wood vinegar was treated with iron or copper.