Working Deep in a Northamptonshire wood, Hugh Ross and Carolyn Church are charcoal burners, practising a 5,500 year-old skill
A plume of perfectly white smoke billows from a circular steel kiln in a woodland clearing.
On this still day, the cloud mushrooms dramatically into the blue sky. The woods are peaceful except for the sound of birdsong and the occasional penetrating cry of a peacock, one of a large flock that roams the area. Hugh Ross and Carolyn Church are tending the kiln, which sits in the heart of Rawhaw Wood in Kettering, Northamptonshire.
For the next 24 hours, the couple will check the steel cylinder as a special alchemy takes place. Inside it just over one tonne of wood is being converted into pure charcoal. “This is a slow, quiet process, which cannot be hurried,” explains Carolyn.
The couple have been living in and working this 30-acre patch of ancient woodland for the past 20 years. In winter, they manage the wood by coppicing, manually thinning out the layers of wood. They cut down larger trees or remove branches to allow more sunlight into the wood and encourage new growth. From Easter to the end of September however their days revolve around making charcoal.
Charcoal is half-burnt wood, which is slowly and evenly cooked, rather than rapidly burnt. This gets rid of water and naturally-occurring compounds such as methane, hydrogen and tar. Once the heat has removed these substances, wood in a near-pure carbon form is left. One of the oldest chemical processes known to man, it creates an ideal fuel, burning with little smoke and strong heat.
Now mainly used for barbecues, charcoal was an essential fuel source for at least 5,500 years. It fuelled both the Bronze and Iron Ages. Without it, the metal ores could not have been heated to a high enough temperature for smelting.
“Charcoal burning is an ancient skill,” says Hugh. “We do appreciate that we’re doing something that has been going on for centuries.”
Living with the land
Carolyn and Hugh were working as volunteers for a wildlife trust when they became interested in woodland. “We wanted to live and work in the countryside, but we knew we weren’t farmers,” explains Carolyn. “We share a love of trees and decided that woodland management was something we could make a living at. A land agent told us that this wood was up for sale, and we came to view it. The wood had the right mix of trees, with hazel, ash, field maple and oak, to make it a commercial proposition. We could use hazel for hurdles, pea sticks, and stakes and binders for hedge laying. We could use a mixture of different woods for making charcoal which we could then sell.”
They bought the land, arriving in 1995 with their young son Kier and their dog. They had only a caravan to live in and a horsebox to store their tools. The woodland had been badly neglected, and this spurred them to produce charcoal. “We were cutting down a lot of poorly grown coppice, which left us with excess wood. Turning it into charcoal to sell was the obvious solution, as these tend to be narrow bits of wood, not much use for anything else,” says Carolyn.
Controlling the fire
The key to charcoal burning is the control of air to the fire. For this reason it is done in a kiln with a lid and air vents that can be opened and closed as necessary. Hugh and Carolyn’s kiln is 6ft (1.8m) in diameter and just under 4ft (1.2m) tall. It was made from steel in Nantwich, Cheshire, by a specialist kiln maker.
To make the charcoal, the wood is cut and stacked ready to be loaded into the kiln. Hugh and Carolyn use all the types of timber found in the wood. “Each has different qualities,” explains Hugh. “Hazel burns hot and fast, oak burns less hot and for longer, and it’s the same with ash. Mixing together different woods works well in terms of the overall burn on the barbecue.”
The wood has been cut from trees during the winter when the sap is down. It is partly dried by the time the charcoal season begins at Easter. In spring, it is sawn up and stacked. Any wood over 4in (10cm) in diameter has to be split, or it is too big to be made into charcoal. A small tractor and trailer trundles the loads on the five-minute journey to the kiln. “Our tractor is so old we have had wrens nesting in the holes in the canopy, but it does the job,” says Carolyn.
Once at the kiln, the wood is sorted into sizes, from 1-4in (2.5-10cm) in diameter. Working methodically, Hugh and Carolyn load it into the kiln, starting with the smallest pieces. “I like the days when we do this. We can listen to the cricket on the radio as we stack. It’s very peaceful,” says Carolyn.
Building the fire
Hugh stands inside the kiln to lay the wood in a criss-cross pattern around four metal inlet ports. These channel air into the kiln to regulate the fire. “We want the kiln to be as full as possible, but we also need some gaps. This allows the air to circulate and we get a more even burn,” he says. In the centre of the kiln, a setting called
a fire site is created. This is where the fire will eventually be kindled. It is laid with brown ends or semi-charcoaled pieces of wood saved from previous batches. These are used because they catch light more quickly than regular wood would do.
It takes just over one tonne of wood to fill the kiln. “When it is full, we crown the top a little, so it fills the conical lid,” says Hugh. The lid is placed on the kiln but not sealed. “We need a good flow of air to get the heat up,” he explains.
A diesel-soaked rag secured to a long stick is lit and passed along one of the fire inlet ports at the base of the kiln. Smoke starts to seep out. After approximately an hour, the temperature rises. Smoke now billows from the kiln rim, rising into the sky like a column. “At this stage, it’s mainly steam, so it feels damp when you stand near it. It’s not an intense heat at first, although it can feel pretty warm on a summer’s day,” says Hugh.
The kiln lid is now lowered and four chimneys measuring 4ft (1.2m) high are put in place. They are fitted into pre-made slots attached to the metal box channels on which the kiln sits. Air is drawn into the kiln through the inlet ports. Exhaust fumes leave via the chimneys. The fire is slow, so the timber is cooked, rather than burning away into soft ash.
Once everything is in place, it is left for 24 hours to burn. Temperatures need to hit at least 375°C in order to start the conversion process from wood to charcoal. They can reach
as high as 500°C. “During this time, the impurities, the sap and the resin, are driven off,” explains Hugh. “We can tell what stage the burn is at by reading the smoke. Grey with
a hint of yellow, for example, indicates that the wood is in the latter stages of a burn. In the end, it turns blue and starts to smell like a barbecue, rather than woodsmoke.”
The kiln is usually lit during the late afternoon and left to burn throughout the night. “We always check the progress in the night. If it is windy, for example, we need to shield one of the inlets to maintain a steady burn,” says Hugh. “It is silent in the wood after dark, apart from the sounds of creatures scurrying about, field mice, perhaps an owl screeching.”
Once the kiln is emitting blue smoke, the burn is complete. The chimneys are removed and small caps are placed on the inlets. Any gaps are sealed with sand so no oxygen can get in to keep the fire alight. Once the kiln has been smothered, it is left for up to 48 hours to cool. The lid is then lifted, releasing an intense tangy smell like smoked kippers. The centre of the kiln has burnt out, leaving a doughnut of charcoal around the edges. Hugh and Carolyn sort through this, wearing protective suits and gloves against the dust and grime. “The dust is not dangerous, but we only have a stand pipe for water in the wood, so we like to keep as clean as possible to cut down on the washing,” says Carolyn.
A useful fuel
The charcoal is now graded. The couple pass it over a giant sieve made up of two sizes of metal mesh. Large pieces of charcoal are used for barbecue fuel. It is packed straight into 3kg brown paper sacks, weighed on scales, stapled shut and stacked neatly to await delivery to local farm shops and ironmongers. Smaller pieces go to specialist blacksmiths who use it for historical re-enactments where they demonstrate the traditional way of smelting.
Hugh and Carolyn also fill the holes in the lanes and rides which criss-cross the woodland with them. “And we use them and the dust in our compost toilet,” says Carolyn. “Absolutely nothing is wasted.”
The kiln is then raked out to remove any tar, a natural by-product of the burning process, and the charcoal burning cycle starts again. The couple usually produce approximately three tonnes each year. “By the end of September we are a
bit sick of charcoal, but then it’s back to coppicing,” smiles Carolyn. “There is always so much to do, I have never been bored in 20 years of living here.”
The couple live in a sturdy oak-framed house, which they built in the wood. It is only a few yards away from the charcoal kiln so work is always nearby. “We haven’t had a holiday since we arrived here, and we haven’t felt in desperate need of one either,” admits Carolyn. “What we do can be very physically demanding, but if you love something, then
it doesn’t really feel like work.”
The history of charcoal burning
As far back as 5,500 years ago, the use of charcoal was commonplace. Whereas pure copper could be smelted at about 800°C, only charcoal would burn at the 1000°C temperatures required to produce bronze from tin and copper. Bronze was hard-wearing, and ideal for making swords, axes and tools. Charcoal production grew steadily, and by 1,000BC its production was a major industry. By AD43-410, iron was being produced on
a large scale. Archaeological evidence indicates that thousands of acres of coppice were efficiently managed to produce enough wood to keep up with demand. The by-products of charcoal, such as tar, were used to caulk ships.
By 1334, charcoal had found a new use, as a component of gunpowder. Then in 1735, it was discovered that coal could be converted to coke, which produces a higher temperature. The new fuel was more efficient and within a century, most of the charcoal furnaces had converted to coke. Over 4,000 years of charcoal use as an industrial fuel were over. Today, only approximately 100 people in the UK produce charcoal commercially.
Most of Carolyn and Hugh’s charcoal is sold for barbecue fuel. However, they also produce approximately 200 charcoal pencils for artists each year. These are made from willow twigs cut into lengths and placed in a small steel cylinder. This then sits on top of the box channels at the bottom of the kiln. Keeping the fragile pencils separate from the larger chunks of wood ensures they are not crushed.
Words: Fiona Cumberpatch▯ Photography: Clive Doyle