fire - making charcoal

7/31/2019 Fire - Making Charcoal

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Making Charcoal

Making charcoal is surprisingly easy. But it is not something you want to do in your backyard except in smallquantities. The method I describe here is what is known as the retort or indirect method. Basically, wood isplaced in a container and cooked. All the volatile gases are driven off and charcoal remains. This is exactly themethod used be the wood chemical industry before petrochemicals superceded it. We, however are going to usethese volatile gases as fuel for the charcoal making fire. Almost like pulling yourself of by your bootstraps but notquite.

The concept is simple. Start a fire under the container. Begin driving off the gases. Route these gases backunder the container. Ignite the gases with the fire already burning under the container. Use these gases to driveof more gas and ignite without adding any other fuel to the fire. When the gas is all driven off the fire dies. Leteverything cool off, open the container and you have charcoal.

I use pine charcoal. It burns hot and clean with virtually no ash. It also burns fast. I burn up a lot of charcoalwhen I am forging. I have tried hardwood charcoal in my forge but it seems to burn down to a lot of ash and smalpieces restricting the air flow. I also have a hard time getting it to welding heat. Small blades such as kniveswere fine, but I could not seem to generate the heat I needed for the large hunks of steel I forge and weld.

I get my raw material from construction sites. I have never had anybody tell me no when I ask to pick up theircutoff scrap. For me this is ideal raw material. It is scrap that would go in a land fill. It is already the right size forefficient cooking and it has already been dried. This is important. If you use green wood you will use a lot ofenergy just driving off the water. This is the only material I have ever used. If you use something else you arebreaking new ground and will have to experiment with the info I give you here.

One caveat here. Never use pressure treated wood. One of the ingredients is arsenic. You do not what to burnit and release the vapors for you or anyone else to breathe. If you are not sure whether piece of wood is pressuretreated leave it. The same goes for plywood, the glues and binders can be nasty stuff.

The method I use requires 55 gallon barrels. Once you get the idea I am sure you can modify this method to suiteyour needs.


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The first thing you need is a barrelor barrels depending on how bigyou want to go. Pictured below isthe type barrel you need. Payattention here.This barrel has a removable lidand bung hole in the bottom. Bothfeatures are important. Withoutthe removable lid you cannot load

your wood, reseal it and then openit to get your charcoal out. Throwaway the rubber seal that comeswith it. You will just melt it andmake a big mess if you try to useit. The bung hole in the bottommakes it easy to get the gasesout. This hole accepts 2" threadediron pipe. Most towns have acompany that recycles barrels.These cost me $25 each.

The picture below shows thearrangement of the barrels. I used1" threaded pipe to make thestand but anything will work thatwill take the heat.The 2" pipe for each barrelconsists of 1-male/female elbowthat screws into the barrel. 2-female/female elbows. 1-6" pipe,

1-24" pipe, 1-36" pipe and 1-endcap. I was lucky. My localhardware store had these sizesalready made up. I drilled 1/2"holes every 6" down each side ofthe 36" pipe that goes under thebarrel. When I screwed it in Imade sure the holes were pointingleft and right so that the flameswould be directed around bothsides of the barrel. That's it . Nowyou are ready to enclose it.

This might would work if you did notenclose it but you would have touse a lot more fuel. I just usedconcrete blocks dry stacked. Theyare not ideal. Some of themcracked from the heat. But it stillworks pretty good. Once thebarrels are loaded, I just stack moreblocks in the front. I use 4" solid

blocks for the last row in order tocreate a gap for smoke to escapeand create a good air flow to fuelthe fire.

I used hollow 4" blocks for the top.Slide them over 1" iron pipe forsupport. 2 pipes for each row ofblocks. You might have to chip out

some concrete in the cavities toget the pipe through.

Create a hole in the back of thekiln in order to add fuel to the fireand allow air in for combustion. Idid this one with some creativestacking.

Here is the raw material. This isenough for one barrel. For a twobarrel burn, you need about threebarrels worth of scrap. Two to

make charcoal out of, one for fuel.

Now you are ready to make somecharcoal. Load the barrel(s) withthe short stuff. Around 12" orless. Use the longer pieces forfuel. Don't pack the wood into the

barrel. There needs to be somespace for the gas to escape thewood. If you are too neat abouthow you put the wood in, it is liketrying to char one big piece ofwood.

Put the wood in, clamp the lid onand stack the blocks in front of theopening.

Go around to the back and stackwood under the barrels, a lot of it.You want to make a whopping hotfire. Get the fire going and keep itgoing good and hot. A single barrelwill take about 20-30 minutes tostart producing gas. Twin barrels

about 45.


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The gasses will start slowly andyou will see flames just licking outof the holes drilled in the bottompipe. In about 5 or 10 minutes itwill be like a pressurized gas valvewas turned on. Flames will shootout the holes, hit the side wallstravel up and around the barrelsand possibly shoot out the top gap

accompanied by a loud roaringsound. Hardwood may not be asdramatic but pine really puts on ashow.

Once the gases ignite, you don'tneed to add any more fuel. In factyou probably won't want to go nearit. During the first part of the burnthere will be a lot of smoke, someof it quite black. Once it really getsgoing though, there will just be anincredible amount of heat. Let itburn until the fire dies on its own,

about 2 hours. This means all thegases have been driven off. It isbest to let it cool down overnight.Opening it too soon and allowingair in can ignite the hot charcoal.

The next day open it up and shovelout your charcoal. Wear arespirator, there will be a lot of finecharcoal dust in the air as youshovel it.Here is the charcoal just afteropening the lids. You can get someidea of the volume loss bycomparing to the picture before the

burn. Not to bad. Much less thanthe direct method. But we had toburn nearly a barrels worth of woodfor fuel. So in the end it may alleven out. You can't get somethingfor nothing

Here is a close up of the wood inthe front part of the barrel.

Here is a close up of an individualpiece. it is charred all the waythrough.

Here This is all the wood that didnot char all the way through. Thisis fairly typical amount for a burn.

Here is the yield. Two and a half 32gallon trash bagsMaking charcoal can be timeconsuming but it is not hard and it isfun. There is something satisfyingabout loading scrap wood in a

barrel, applying fire then removing adifferent substance from the barrel.Makes you feel like the alchemist ofold.

fire - making charcoal

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