Hello folks,
I am going into another busy year. House projects are underway, but also nearing completion. I am really hoping I don’t spend the whole year being busy like I did last year, but I am also really bad at being idle. As such, it should come as no surprise that I came up with new ways to keep myself occupied. At least there is more time for the fun things I want to do, and less of the things I have to do. The struggle of modern life, am I right?
So let’s jump right into it shall we? As a blacksmith, and with an academic background and dabbling interest in experimental archaeology, I am often in need of charcoal. Not coal, but charcoal. Charcoal is made be burning wood (or other organic material) in the absence of oxygen, leaving the carbon mostly unburnt. In a previous post, I talked about the process of how to make charcoal in pits. Pit charcoal is among the oldest ways that humans had made charcoal.
This post is an updated version of mostly the same process, with some added tools. It starts out the same, with small pieces of wood. But instead of this pit, this time around we are using barrels.
The Design
To build my charcoal kilns, I needed a 55 gallon metal drum. The ideal would be with a removable snap ring lid, but I wasn’t that wasn’t available to me. So I made due with a closed lid barrel, and made my own sealing method. It is a 12″x12″ iron plate, a 1″ flange, pipe, and cap. I used self tapping screws to secure the flange to the plate. Voila! Small smoke stack.
After that I used my angle grinder to cut a hole in the top of the barrels, and my drill to create 8 1″ holes around the bottom. The hole cut out of the barrel is less than 12×12″, so that the plate fits on top instead of falling down into the barrel.
I set these barrels into shallow pits, because it makes closing the lower holes easier. More on that in a moment.
The Process
After the barrels are all cut out and set up, the process is much the same as making pit fired charcoal. You load up the barrel with cut/split wood, and light it up from the top. This make take a few tries and some patience, and I find that using some charcoal under your kindling can really help get things going. I use mostly dried pine and spruce bits. They take fire real easy, and then also stay burning for a while.
Once it is burning, give it some time to light the wood underneath and deeper in the barrel. When I have a good bed of burning charcoal underneath the fire, I put a poker down into the barrel and get the embers to drop down. This opens up the fire to air from the lower holes, and also knocks down the burning embers so the barrel starts burning from the bottom.
Once the embers have fallen down the bottom, they will ignite and start to take oxygen from the 1″ holes at the bottom of the barrel. When this happens, my barrels start to make an audible hum that I think sounds a bit like a rocket engine. This means it is time to start thinking about choking off the oxygen. If it goes on too long, you won’t have anything left but ash.
At this stage I start by putting the chimney setup on the barrel, and leaving the cap off. I seal the smoke stack assembly with dirt so smoke doesn’t get out. This starts to choke off the oxygen at the top, while still allow water vapor and smoke to vent.
After a while, I will use a shovel and some dirt to cover up the holes at the bottom of the barrel. This is where the small pit comes in handy, because it makes this easier. You can do it on the ground too, but I like 1) having a small pile from the pit, and 2) it makes burying the holes easier and uses less dirt.
This step removes all oxygen from the fire in the barrel, and so it will start to go out. I let it burn until the chimney isn’t smoking much, and then cap that off too. There should be residual heat in the barrel that will continue to cook what is left in the barrel.
Then I leave the barrels to cool overnight, and the next day I get to see what I got. If I do everything right, I will get about 40% volume charcoal compared to the amount of wood I put in. It is not unusual for there to be some pieces that have not fully charred, and I just set those aside for the next batch. They catch fire a lot easier, and will burn to charcoal in the next batch.
Once I get the charcoal out of the barrels, I sift it (about 1/4″ mesh) over a wheelbarrow and send it to storage. The larger pieces will make great fuel for the forge. The small pieces get spread and tilled into my garden as biochar, and a ready carbon source for the soil and plants.
There is not much to it beyond that. It will take some trial and error to get good charcoal, and heck I’m still making adjustments. But it is a pretty inexpensive way to make a kiln for charcoal.
As always,
Thanks for reading!
The Thought Forge 