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Charcoal Burning The ancient art of charcoal burning provided a living for thousands of woodcolliers along the valley for many hundreds of years. Charcoal was once a major source of fuel, not just for domestic use but also for major industry. Charcoal today tends to be associated with barbeques but in reality is an extremely versatile product used in everything from medicine and horticulture, to industrial processing and filtration. The manufacture of gunpowder also used charcoal as a major ingredient. Locally made charcoal is renowned for its quality and effectiveness and is made from wood harvested from sustainable sources, unlike most of the imported varieties. Sylvan Charcoal, a local charcoal maker, provides the opportunity to see for yourself how charcoal is made. Read on . . . |
Wey CHARCOAL IN TONGUES ~trækul (Danish) |
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An Ancient Sustainable Practice The first evidence that charcoal was used by humans dates back as far as 30,000 BC. European usage started 5,000 years or so ago and was eventually to become important in the manufacture of gunpowder and the Wealden Iron Industry along the Wey Valley. The intense and steady heat provided by burning charcoal is absolutely ideal for the smelting of metals which includes iron and copper. No other natural fuel could provide the temperatures of 1,000°C needed to smelt tin and copper to produce bronze, an all important metal for the manufacture of swords, axes, tools and jewelry in the Bronze Age along the Wey Valley. The mass production of charcoal for industrial use along the Wey began to die out in the eighteenth century after new processes were developed to convert coal into the intense burning coke, and within a century virtually all of the commercial charcoal kiln had converted. Almost all of the estimated 6,000 tonnes of charcoal used in Britain annually is imported from countries with low labour costs where wood is usually taken from non-sustainable sources, such as the endangered South American tropical forests, and mangrove swamps in south-east Asia. There are British manufacturers but their output represents less than 5% of the national demand, with the majority of these being small businesses who cannot compete with the low prices of the bulk importers. However these local manufacturers on the whole use wood from sustainable sources, and there are a number in the Wey Valley. In sustainable methods wood is taken from coppices, a method that certainly predates 500 BC in the valley. The Romans are credited with the rapid promotion of coppicing from AD 43 as charcoal was vital to the large-scale iron production needed by them to maintain their occupation of Britain. In coppicing, trees are cut down to a stump, or stool, and the new growth of shoots is encouraged. These shoots growing from the edge of the stool grow into branches, or poles, which once large enough are harvested for charcoal making. Some species of tree produce rapid growth of poles with a rate of six and a half feet a year (2 m) being quite common. This method can produce an indefinite supply of wood without the need for replanting, with many ancient coppices having been active for hundreds of years. Hazel, ash, oak and lime trees are the established species for charcoal production. How Charcoal is Made Timber collected from the coppiced woods is cut, collected and left to dry out, with the drying process usually taking between six months and a year to complete. It is possible to make good quality charcoal from green wood, that is wood freshly cut and that has not been allowed to dry out, although this takes considerably more energy. Once dry the wood is split lengthways into 5 inch (13 cm) poles and then cut into shorter sections of about 3 feet (0.9 m )in order to fit into the kiln. Charcoal is made by heating wood to a temperature of over 270°C in the absence of air and so the kilns are specially designed to minimise the amount of air circulation in order to provide for a carefully controlled burning, a process that requires considerable expertise to provide good quality charcoal. The controlled burn can take from 24 hours to several days depending upon the type of kiln used, and requires considerable monitoring and adjustment of air intake to perfect. Most charcoal manufacture in the valley is carried out in portable kilns. These are usually circular steel drums of approximately 8 feet (2.4 m) and at least 4 feet (1.2 m) in height. The kiln is topped with a removable lid and chimneys venting from the base of the kiln remove the smoke and gases. Ancient kilns tended to be dug into the ground to operate as earth kilns. Larger commercial operators use retort kilns which keep the wood to be burned separate from direct flame. The term 'retort' refers to the fact that gasses emitted from the burning wood are sucked back into a central fire box which produces the heat for the burn more efficiently. Retort kilns provide for a faster burn and greater ease of loading and unloading. The timber is placed in layers leaving a centrally positioned void in which the fire used to burn the wood is set. Once the fire is established the lid is initially placed loosely on the kiln allowing the charcoal maker to monitor and adjust the flow of air and hence adjust the speed of the burn. After a couple of hours the lid is completely sealed and the burning process is made to die down. The kiln is then left for up to several days to cool down before the charcoal is removed. It takes approximately 8 tonnes of wood to produce 1 tonne of charcoal. Local charcoal tends to be a lot easier to light and provides a quicker and more consistent source of heat than imported varieties. This quality is aided by the fact that the local wood used is a lot less dense than imported varieties. The sustainability of the wood used also contributes considerably to local wildlife habitats and greatly boosts the biodiversity of the woodland areas it is harvested from. LOOK IN ON THE BOYS FROM THE BLACK-STUFF The Life of a Woodcollier Charcoal makers are also known as woodcolliers. The many woodcolliers working in the valley a few hundred years ago would spend most of the burning season living in the woods to ensure not only a consistent burn, but also to prevent any outbreak of fire. The very nature of their charcoal production meant that any carelessness could result in a kiln catching fire and the surrounding woodland combusting too. Often having to live by their kilns for up to twenty-three weeks it was common for their families to join them too during the season. Traditional woodcollier shelters were built using poles lashed together to form a teepee which were then covered in sacks and brushwood with turf stacked on top to keep the weather out. The turf was layered to provide an efficient seal. The woodcollier and any family members joining him would sleep on platforms constructed from stakes and staves to keep bedding above the damp ground. Documentation from the First World War show that a productive woodcollier could earn between 20 and 30 shillings (£1 - £1.50) a week, equivalent to the earnings of a junior silversmith at the time. The woodcollier would also supplement his income by making baskets and brooms. As well as selling the charcoal direct it was common for charcoal merchants to tour the valley and buy up production to transport to major settlements and sell on to industrial users. Why is Charcoal such an Efficient Fuel? It does seem strange that in order to produce a fuel that provides an efficient output of heat that it is necessary to burn it to start with. However charcoal burns at twice the heat of wood. Here's why. Wood goes through three phases of burn process when ignited.
It is possible to push the process further to make perfect 100% carbonised charcoal by getting rid of any remaining tarry substances by raising the temperature above 600°C. Useful By-products Large commercial charcoal burners have the opportunity of converting the by-products of the burn. All the vapours and gases escaping as smoke can be recovered by passing the gases through water based processes to yield pyroligneous acid. Remaining non-condensible gases can be burned to produce heat. Pyroligneous acid contains tar which can be separated out and recovered to be used in wood preservatives, caulking agents, road tars and even as a veterinary antiseptic. The Versatility of Charcoal Most of us encounter charcoal simply as a fuel to be used on our barbecues in the summer months. However it is an extremely versatile product with many other uses. These include:
Charcoal Making There are a number of woodcolliers currently operating in the valley producing various levels of output. Ian Baldwin runs regular charcoal burns during the summer months in the E$lstead area and encourages allcomers to muck in and find out for themselves just how charcoal is made. There is no charge for coming along, but you would in return be expected to break into a sweat and provide Ian with much welcomed help. Ian is also immensely proud that he has inspired a number of his helpers to set up their own successful charcoal-making businesses. SEE THE BOYS FROM THE BLACK STUFF IN ACTION GO ON - SUPPORT YOUR LOCAL CHARCOAL MAKERS If you want to find out more contact Ian direct. IAN BALDWIN ALL ABOUT GUNPOWDER MANUFACTURE © Wey River 2005 - 2012 |
