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Any new small charcoal retorts out there?

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Depends what it was treated with.


The wood is going to get a lot hotter as you burn it than it did when you pyrolysed it. This means different things will come off. If you can be confident that the wood was treated with an organic biocide (the type of thing you can buy in B&Q) then it will have thermally decomposed, just like the wood has. If it was commercially treated then it could be copper, if it's modern it could potentially be boron-based, if it's older it could well be copper chrome arsenate (CCA). Burning the charcoal will also add oxygen, so the remaining compounds will convert to oxides. I don't fancy arsenic trioxide flavouring on my burgers myself....




Come on Alec, it adds a nice salty flavour.

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Come on Alec, it adds a nice salty flavour.


True, and the hexavalent chrome adds a nice yellow colour and a slight tang, a bit like mustard :001_smile:

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Stumbled across this video a few days ago and it looks interesting, and more importantly, cheap to build.



Reckon there's room for improvement (there is a follow up video where he covers some people's questions) but I reckon it gives a good starting point for a back garden burner.


I'd be looking to make the inner drum vent to the base rather than out the top to utilise more of the burning gas but not sure whether it would be easier to keep the inner drum fixed and try and seal the top or make the inner drum removable and put it in upside down (maybe use a hinged lid and catch).


I've been playing around with an old 5ltr paint tin and a small garden incinerator the last few nights with mostly success but it's been fairly labour intensive and not very efficient as there's not much room to get a decent fire going to it needs plenty of attention until it starts running on the gases. A bigger outer drum would help with that though and that might be mark 2.


When I find where I've left the camera I'll get some pics of the next burn.

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Hi Richard,

Just graded batch 2 (the photo) and got approx 40x 3kg bags and about 30 kg of graded (20mm fragments) of BioChar.


Grading Single species (6kg) Ash Charcoal this morning.

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