How It Is Made
- The process starts with filling the kilns with timber, placing smaller pieces on the outside and larger pieces towards the centre. Each traditional kiln holds about 1 tonne of wood.
- To allow air flow the lids are propped open then a fire is started at the base, in the middle of the kiln. The fire is allowed to grow whilst being monitored to make sure it is distributed evenly. Once hot enough (usually after about 30 - 40 minutes) the lids are dropped and sealed, as is the gap at the bottom of the kiln. This forces the air out through the chimneys and draws it in through the ports at the base.
- Now that the air is flowing through the kiln efficiently, the ports are partially covered to restrict the amount of air flowing into the kiln. This helps control the length of the burn by restricting the amount of oxygen. Restricting the oxygen prevents combustion and allows the heat to build, driving out water, sap and other organic materials.
- The next part is a waiting game, allowing enough time for the water and sap to be entirely driven out of the wood, leaving charcoal. This is indicated by the colour of the smoke from the chimneys, thinning out and developing a blue tint. Once the charcoal is cooked the chimneys are removed and earth is used to block the vents and seal the kiln. It is then allowed to cool before emptying.