Charcoal burning

Part of the Walter’s Tools project plan over the summer is to run a series of five weekend workshops in woodland trades and crafts, run by expert tutors. We lined up a charcoal maker (as Walter used to be), a blacksmith, a tool handle maker, a scyther and haymaker, and a willow basket maker.

charcoal kiln group

Photo: Dayve Ward

First up back in June, coppice worker Sam Ansell from the Coppice Co-op ran a workshop for us  at Stott Park Bobbin Mill, where our tool library will end up, showing participants how to make BBQ charcoal.

One of the participants, Adam, wrote a thorough account of the process:

On Saturday morning we began stacking the kiln. The kiln we were using was a small ring kiln, comprising an open-ended metal cylinder with a sealable lid and 6 vents that over the course of the burn alternately acted as air intakes and chimneys. Sam had already sited the kiln, surrounding the base with sand to prevent smoke from escaping from under the edge.

Our first task was to create an open bottom layer that would allow air to be drawn into the middle of the kiln from all of the vents. In order to do this, we selected longer lengths of wood and carefully placed them in a form similar to the spokes of a cartwheel, so that each vent opened into a wooden-sided passage that led to the middle. We roofed over these passages with smaller logs and filled in the gaps between, added a layer of kindling and then proceeded to fill the kiln, placing the logs in a parabola pattern, larger logs to the centre (which burns hotter than the outside). We stacked logs to above the height of the top of the kiln, so that the lid rested on top.

We lit the kiln by pushing in a paraffin-soaked rag, and watched as thick white smoke began to billow out from under the lid. We left vents open and lid unsealed for around an hour, creating a high air flow and encouraging the kiln to burn hot so that enough heat would be retained throughout the burn. At this point we made the seal around the bottom of the kiln more robust, building a small earthwork of turf and mud.

charcoal kiln vent

Photo: Dayve Ward

After around an hour, when the lid had begun to settle, we removed the chocks and carefully lowered the lid, resulting in an exciting burst of flames from the vents. Once that had settled down we placed metal chimneys onto three of the vents and sealed them with turf and mud, leaving three open to draw air into the centre of the kiln. We also dabbed sand into the rim to seal there.

From then on the process involved much philosophical debate and tea-drinking. Every two hours we swapped chimneys onto the open vents to ensure that the wood was charred evenly throughout the kiln (the hottest part of the burn occurs where the air enters). We allowed the kiln to burn for around ten hours, which was a little on the short side but fit the purposes of the workshop and allowed us to get a good night’s sleep while the kiln cooled. We shut the kiln down by removing the chimneys and sealing the vents, preventing air intake into the kiln and suffocating the burn.

earth burn

Photo: John Ashton

We removed the lid from the kiln at around 11am the next day and stared into a half-full can of shiny, crunchy black charcoal. As the kiln was going to be taken back to Sam’s yard, we simply rolled off the ring after removing some of the sealing turf – the larger ring kilns that he uses to make charcoal to sell are well-sited and remain in the same position, although generally it is most efficient to make charcoal in situ, in the woods, as it is a lot easier to haul out than the much heavier logs.

Adam & Sam open kiln

We shovelled our pile of charcoal (which could have done with an hour or two longer to cool, as some was still smouldering) onto the grader, which we spun by hand to separate the ash from the charcoal, ‘brown ends’ (bits that hadn’t completely converted into charcoal and can be used to start the next burn) and tiny charcoal fines (which can be used as a soil improver and in recent years have been hailed by soil scientists as a potential world-saver and given the superhero name ‘Biochar’).

adam shovelling

Larger pieces needed to be checked by breaking them apart, to enure that they had converted to charcoal all the way through. Those which had not were discarded.

grading charcoal

We bagged up our product and stacked it, ready for the barbecue, tidied up, and had another cup of tea.

bagging

charcoal sacks

********************************************************************************************************************************

This workshop was part of a public open day at Stott Park, and our kiln charcoal burning workshop was run parallel to an earth burn with Windermere Reflections.

Here they are putting out the fire ~

charcoal sign

Uncovering the earth burn

In amongst it all were several tins of willow.

lifting out artists charcoal

These were dug out and opened to reveal artist’s charcoal.

artists charcoal

That evening I had a barbeque with some of the charcoal and it was delightful. It got going quickly, without being coated in nasty flammable liquid that is characteristic of commercial charcoal. It was also very special to be cooking food with fuel that was from within a short distance of where I live.

Below are some charcoal burners in the woods near here at the turn of the 20th century and as you can see the scene has not much changed.

charcoal-burners-599x224

(source ~ http://www.armitt.com)

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