Charcoal making: introduction

What is charcoal making?

Charcoal making involves burning wood whilst controlling the amount of oxygen present. Very little oxygen is allowed in, and the slow burn results in a product (charcoal) that burns at very high temperatures, but produces very little (if any) smoke. Charcoal is one of the oldest commodities in the world. It provided the heat to smelt metals like iron and copper – so without it, the bronze age, iron age and industrial revolution wouldn’t have been possible. Nowadays, charcoal is produced in metal kilns, but originally it was made in earth clamps by piling up wood, covering it with turf to control the ingress of oxygen, and burning it slowly.

starting to stack wood in the kiln, with kindling in the middle

Starting to stack wood in the kiln, with kindling in the middle.

Coppicing was the usual way to provide wood for producing charcoal in a perpetually recurring cycle – but alas, as with most resources, it was over-exploited and resulted in massive deforestation in Europe and North America.

3 kilns during a burn

3 kilns during a burn.

Charcoal has traditionally been used for blacksmiths’ forges; for drawing; as an ingredient in gunpowder; as a soil additive; for filtration; and for cooking. Nowadays most charcoal is used for barbecues. Charcoal briquettes are made by compressing charcoal made from sawdust etc, along with dust and a binder; lump charcoal is just the raw product from burning hardwoods.

What are the benefits of charcoal making?

lifting the lid after the burn

Lifting the lid after the burn.

  • provides a market for poor-quality wood, although there’s much more of a market now for firewood, due to the recent increase in the use of wood stoves
  • buying locally-produced charcoal reduces the transport involved with imported charcoal, provides local employment and supports the local economy
  • helps manage woodlands; woods need to be thinned to produce a wide range of products, including timber, firewood and charcoal
  • locally-produced charcoal is a renewable, sustainable resource because the carbon released on burning is balanced by the carbon taken up by growing trees, and so cooking over charcoal saves on non-renewable fossil fuels

Great video showing the charcoal-making process by our friends Pete & Anna at the Bulworthy Project.

What can I do?

Getting started

You can make charcoal for your own use, and there is a small but growing number of people doing it commercially. It would be difficult to make a living from charcoal burning alone, but it could work as one element of a woodland business such as tree surgery, forestry contracting, timber products, courses, firewood etc. The biggest market is for barbecue charcoal (and there are a few specialist suppliers of artists’ charcoal).

freshly-made charcoal

Freshly-made charcoal.

More and more people are buying small woodlands, or you could negotiate the use of someone else’s wood. Ask the Forestry Commission, the Woodland Trust, agents for large estates, or people you know with woodland. You may be able to produce charcoal there for free. If you don’t ask, you don’t get. However, the firewood market has taken off recently, so there is more demand for poor-quality hardwoods – the same raw material as for charcoal burning. So you may have to pay for the wood, even if you can put your kiln on the land for free. You could pay a forestry contractor to deliver timber to your kiln. Arborists working on street or garden trees often have a lot of cut crown wood from the tops of trees that they may have to pay to get rid of (local authorities sometimes charge £15-20 per load of waste wood, and convert it into woodchip and compost). They may be happy to deliver it to you for free.

lifting the charcoal out of the kiln with a fork

Lifting the charcoal out of the kiln with a fork.

Start by attending a charcoal making course to see how it’s done and to have a go. Then buy a kiln, or if you only want a small one, you could convert a 45-gallon oil drum. There’s an explanation of how to do this in Coppicing and Coppice Crafts by Rebecca Oaks and Edward Mills. But you have to learn the art of charcoal making by actually doing it. Charcoal burning a scientific process, but there are so many variables, that it really does become an imprecise art. Variables include:

  • species of wood used
  • moisture content of the wood
  • how wet the ground is and whether it’s free-draining or not (clay soils can be problematic, as a huge amount of water is driven off during the burn, and it has to go somewhere)
  • the wind can inject unwanted oxygen; you can put hurdles around the kiln, although this is more of a problem on open land than in enclosed woodland
  • the time of year
  • how much oxygen you let into the burn
  • the skills of the charcoal burner
a biscuit tin of twigs for making artists' charcoal: before and after

Biscuit tin of twigs for making artists’ charcoal: before.

Regulations & other people

Talk to the planning dept. of your local authority first. You don’t need formal planning permission to site your kiln, as it will be temporary, but the local authority won’t like it if local residents complain about smoke in their house or garden. The planners probably won’t know much about charcoal burning, so you might like to invite them and show them a burn. It pays not to get in their bad books.

When you start a burn, before it gets up to operating temperature, there are usually huge clouds of smoke, and someone might call the fire brigade. You must tell the local fire brigade HQ that you are intending to start a controlled burn. Tell them when you’ve closed it down too. Plus it’s polite to tell any neighbours who might be affected by the smoke.

A biscuit tin of twigs for making artists' charcoal: before and after

Biscuit tin of twigs for making artists’ charcoal: after.

You need to get insurance before starting charcoal making. If you already have insurance for your business or for your woodland, then you can add charcoal burning to it.

Managing the burn

There are usually 4 inlet ports and 4 outlet pipes on a kiln. Typically, pipes (or chimneys) are 5″ (13cm) diameter. The inlets are at ground level. These are to control the oxygen input, by covering or partially covering the end of the inlet with a house brick or soil. A burn with a 6ft (2m) diameter ring kiln, approx. 1m high could take around 10 hours, depending on the variables above. Ideally, wood should be up to 4-5″ (10-13cm) diameter, or up to 3″ (8cm) for a small kiln / oil drum.

bagging the charcoal

Bagging the charcoal.

The burn should be managed – you should never leave a lit kiln, and you should stay with it for at least an hour after the burn has finished as well. The whole process from start to finish can take 3-4 days. On day one, get the kiln filled and ready to light. Start day two as early as you can – light the kiln around 5-6am, and be prepared to come home around 12 hours later. It’s best to leave the kiln for 24 hours to cool, so perhaps on day 4, lift the lid and carefully extract the charcoal. Most people use an asphalt / tarmac fork, or a potato fork – one with a good curve and lots of prongs. The charcoal needs to be graded and bagged. Grading can be done on a sloping chute of 17mm mesh (used for rabbit pens, and sold in rolls from pet supply shops). Grading allows small pieces and dust to fall through the holes – dust in the charcoal prevents it from burning well. It can then be tipped into sacks that can be carried easily, for use or for sale.

Kilns can be taken away, or left in the woods. The pipes can be taken home, or if it’s a mini-kiln, everything can be taken away in the back of an estate car. You can get the next load of wood delivered to your kiln, or you can roll the kiln to where the wood is stacked.

Thanks to Maurice Pyle of Woodsmith Experience for information | pics © Maurice Pyle & Ecclesall Woods Sawmill

 


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Anna and Pete Grugeon are partners in Bulworthy Project, the main income of which is from charcoal production. They have been teaching charcoal making since 2010 and have acted as consultants on sustainable charcoal production projects in the UK, Costa Rica and Nigeria. They’re passionate about the role charcoal production can play in sustainable land management.


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