What follows is a brief description of how charcoal is made using a steel ring kiln. The pictures were taken on Bulworthy Project charcoal making courses.
Loading the Kiln
Wooden supports known as feet are placed in a particular way to allow the correct airflow to the middle of the kiln.
“Brown ends” (part charred pieces of wood) are placed in the centre of the kiln to form a “hovel” which is where the fire will be lit.
The first layer of wood known as “bridges” are placed on top of the feet.
Wood is then placed with large pieces towards the centre and small pieces towards the edge. The wood is laid horizontally and positioned radially except immediately on top of “hovel”.
This process is continued until the kiln is full.
The lid is placed on the kiln supported by a bearer on the windward side.
Lighting and Free-Burn
The kiln is lit through one of the outlets.
When the kiln is burning properly, the gap around the bottom of the kiln is filled with sand to prevent air getting in except through the vents.
The chimney outlet ends are blocked with bricks and the chimneys are put in place.
The bearer is removed and the lid is closed.
The lid is sealed with sand.
Controlling the Burn
The kiln is then monitored whilst sitting around the campfire enjoying a glass of wine.
The next morning when the kiln is ready to close down, the chimneys are removed and capped and the inlets are blocked.
When all chimneys have been capped and all inlets blocked, the kiln is left to cool for 24 hours.
The moment of truth when the kiln is opened. If the charcoal is made correctly there should only be a small amount of ash at the bottom of the kiln and the top surface should be even.
Sometimes the top surface will show signs of an uneven burn if there has been a strong wind. Any significant amount of ash on the top of the kiln is a sign that the timing was wrong or the kiln was loaded badly.
The charcoal is removed from the kiln and placed on a grader made using a 25mm mesh to remove dust and any charcoal that is too small.
“Brown ends”, over-charred charcoal are also removed at this stage.
Pieces of charcoal that are too large are broken down into a suitable size.
The charcoal is then put in a bag and sealed.