From Farm to Flame! Our Bone Charcoal

January 30, 2019

We have always looked at our processes, food waste and the impact of what we do on the environment and our farm.  Burning wood to make charcoal has seemed to be a bit of a taboo subject and something that Darren and Jack are often asked about when they are cooking over the fire.  This is what sparked the idea of trialling the bone charcoal (bone char) when Darren spoke with local woodsman, Tom Kemp, and saw a few instagram posts from others who had been making bone char. He was interested to see if it was both a way of using the entire animal as well as potentially reducing the amount of wood we use.

Darren’s Bone Char:

After working with Tom and seeing the process, craft and skill it takes to make charcoal in the way he does, I saw how little fuel it uses and the effectiveness of the method.  The kiln he uses requires him to check the fire every three hours. It’s a real labour of love and artisanal craft.  The wood he burns is a mix of chestnut, cherry and turkey oak which produces charcoal with a high yield that holds its shape and integrity producing large pieces of charcoal that burn for a long time and create great coals for cooking with.

I mentioned the idea of saving up some bones and trialling the bone char.  Tom was keen so we went for it, following a similar process of making charcoal using a mixture of bones from our organic Lamb & Red Devon cattle bones.

Tom placed the bones on the top layer of wood inside the kiln, separated by a sheet of corrugate.  This way they would be the last things to burn in the kiln, using the residual heat to carbonise.  The bones themselves were left as is from out butchery, not cleaned down. Tom assured me that anything that wasn’t bone would just burn away and we’d be left with the bone intact which would be very high in calcium. 

The burn itself took 27 hours! Afterwards, I met Tom in the woods where the kiln was located, not far from Mylor Bridge.  We lifted the lid and we were very pleased with the results. The bones themselves were very much intact, holding their natural shape with a surprising density to them.  They had completely carbonised, and only the bone itself remained, just as Tom had told me. 

We loaded the bones up and took them back to the farm to use on the fire for our cooking.  The bone char itself burned brilliantly. It needed a small amount of normal charcoal to get going, but when it did, the bones glowed an almost amber white, you could really see the only thing left in the bones were calcium when the fire had burnt out. Shards of very white bone char were the only thing that remained. 

Our conclusion with the bone char was that it worked really well and is a great way to use any leftover bones from the animals that aren’t used in stocks and sauces. As for a fuel source, we’d be best off making blends of bone and wood charcoal. This would reduce the amount of wood we actually use in our cooking and mean that we can use each animal in an even more nose-to-tail way. With the butchery being developed currently, our processes on site will mean we have more bones available and this could very well be a way in which we use them.  

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