Petts Wood and Hawkwood charcoal burning

Charcoal burning dates back to 4000 BC. As it burns hotter, cleaner and more evenly than wood, it was crucial in the development of metalworking in the Bronze Age, Iron Age and industrial revolution.

Cave drawings provide some of the earliest evidence of charcoal burning, and for those ancestors living in simple dwellings, it provided a smokeless fuel. Here at Petts Wood and Hawkwood we are pleased to be continuing this ancient practice with the production of barbeque charcoal.


How do you make charcoal?

We use a ring kiln, a technique that charcoal burners (colliers) have been using for over 100 years. Prior to this, they used 'clamps' - earthen mounds which were created by covering the neatly stacked wood. We make use of seasoned wood that has dried for a minimum of one year. This makes for a more even and controllable burn. The wood is packed as tight as possible into the ring kiln to reduce air gaps, with the largest pieces in the centre where it will burn hottest.  The idea is to 'cook' the wood in a low oxygen environment, controlling the speed of the burn.

The colour of the smoke produced is the key indicator of the burn process. In the early stages of the burn white smoke (mostly steam) is produced.  During the latter stages of the burn the smoke becomes more yellow in colour and then a translucent blue, a sign the moisture and tar have been driven off and the burn is complete.  If the burn goes beyond this stage, the charcoal can turn to ash and is therefore wasted.  With our larger kiln the process, including the burn and cool down, takes two to three days with the kiln closely supervised throughout.


What wood is used?

We find that to create the best and most consistent charcoal, it is best to use a single species of wood for the burn.  Silver birch makes a particularly fine charcoal, and as they are relatively short lived and fall frequently, we have a ready supply of this wood.  Most of our charcoal is however made using sycamore, as it is an invasive non-native tree that we often remove from the woods.  It also makes very good barbecue charcoal. We occasionally use alder, hazel, holly and oak too.


Surely, it isn’t good for the environment?

Charcoal burning is part of our woodland management, and we only do this occasionally, on a small-scale, using wood from our estate. Yes, it does produce a lot of smoke when it starts to get going, but the growing trees absorb the carbon, and we don’t burn near anyone’s house – so no smelly washing.


What is charcoal used for?

Throughout history, there have been many used for charcoal, today it's use can still be found in:

  • Drawing

  • Medical use

  • Filtration (water, cookers etc)

  • Shoe insoles

  • Traditional blacksmiths' furnaces

The tar around the kiln was also used for corking between ship planks.

Here at Petts Wood and Hawkwood, we just make lumpwood charcoal for your barbeque, which you can buy knowing you have helped us manage and maintain this lovely site. We sell the charcoal here at Petts Wood and Hawkwood, and from the shop at Ightham Mote, near Sevenoaks.

Any charcoal which isn't large enough for 'lumpwood' is given to the gardeners at another National Trust site, Ightham Mote, to add nutrients to the soil and to make compost.