As you will have realised, I didn’t get the chance to post any further updates during the Earthburn last week. Now finally back home after leaving the Earthburn on Friday and going down to the Weald & Downland Museum for the Steam Festival (where the smoke smelt entirely different but I probably fitted in quite well) I can catch up with the story.
The burn started slowly and deceptively gently. Here Mr Jameson tends to the hay and soil covering as the burn creeps down the stack. By late on the first evening all was going well and in the ‘hurry up and wait’ nature of things it looked as if the hard work was over for a while. By just after midnight the top of the kiln was starting to collapse noticeably as the top tier of wood burned. But I decided to get some sleep and missed all the excitement in the next few hours.
Under the gently exterior the burn was gathering pace and beginning to build up heat. Around about 3am the burn broke through the top of the kiln as woodgas was released and ignited. For the next hours the team fought bravely (or so they told me over breakfast) to contain the burn using water, soil and a few bits of tin lying around the site whilst the heat was gradually reduced and the last of the woodgas burnt off. In my opinion birch has something of a habit of doing this, especially when it’s still slightly green – quite easy to lose your eyebrows and even with my small oildrum kilns it can just about blow the lid off when the gas mixes with oxygen. So I can imagine that controlling a stack of several tons of birch 8 feet tall and 20feet across is quite a dangerous occupation. No wonder a few charcoal burners used to go missing from time to time.
So I missed all of the dramatic photos in the early hours of the morning and by breakfast time it looked as if everything was under control – except that the kiln had reduced in size dramatically overnight. Alan Waters and Mark Cox debate the next course of action.
Peter Jameson demonstrates just how comfortable the one legged charcoal burners stool can be when you’ve been up since 3am.
One of the team drew this very authentic sketch of the scene using willow (artists) charcoal to hand.
As Thursday (day 2) drew onwards the kiln became progressively more peacefull with the last of the moisture and volatiles driven off the fire is burning right down to the level of the hearth and the smoke is starting to turn bluish. It prooved to be a quieter night though still busy as the hay and earth covering is constantly being tended to whilst the wood contracts under it to prevent the fire breaking through again.
The winds were light throughout the burn which was helpful, but it doesn’t need much movement to fan the flames and make it hard to control the burn evenly around the kiln so these screens were erected, gate hurdles covered in hessian, to reduce the air flow over the kiln.
Jimmy on watch over the kiln inspects the drawing his son Jacob has made of the scene, complete with his dad’s coffee mug.
Unfortunately I didn’t get to see the kiln opened as I had to leave for the next show on Friday. It’s not as simple as leaving it to cool, as you do with metal kilns and oil drums as it’s not possible to completely seal the covering. So the fire has to be put out by using water – though its the boiling of the water into steam which actually stops the fire by reducing the heat and excluding the oxygen, rather than by dowsing or drowning the fire. Once it’s been ‘steamed’ the coals can then be collected, sieved and bagged.
Alongside the charcoal burn were a number of greenwood courses taking place and some demonstrations – including the polelathe so I’ll post on these next.
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