Making Charcoal

Charcoal. It’s handy stuff. Lights easy, burns clean, burns hot, easy to make. What’s not to like? Wait, easy to make? Yes! And I’m about to tell you how.
But first, some background. I promise I’ll keep it short.
I’m assuming you already have a basic knowledge about what charcoal is and what you can use it for (besides grilling burgers), and why lump charcoal is far superior to briquettes.
This is my current process. Actually, it’s 4 or 5 steps into an iterative process, eliminating methods along the way that are too complex, too inefficient or too expensive. Its silly if you’re spending $50 to make $30 worth of charcoal, spending hours digging & covering pits, or your process requires hard-to-find materials (like a 30-gallon metal drum). This is my current balance between ease, cost, and availability of materials that virtually anyone can do.
And of course the obligatory warning: This obviously involves fire. You may burn yourself, your property, your house, or that one dumbass chicken who’s always getting into trouble. This is how I do it and you’re on your own if you’re going to copy my brainless stunts. If you want my actual advice, just go to your local store and buy a bag of charcoal.
There, see? Short. Now on to the good stuff:


  • Charcoal wood – The wood you will be turning into charcoal. The precise species and shape (limbs, crotches, knots, solid wood flooring scraps, etc) is not that important, but keep the following in mind:
    • Needs to be cut into smaller chunks. The smaller the pieces, the quicker it will cook, but too small and you end up with crumbly bits (which is perfect for smelting iron or adding to your soil)
    • Dense hardwood is best – Maple, cherry, oak, beech, etc. Every once in a while you’ll find a dense hardwood (like locust) that almost turns into carbon lace. Enjoy the exploration!
    • Avoid composites, plywood, and pine or other softwoods (see “fire wood”).
    • Wood should be absolutely as dry as possible. Do not use green wood.
  • Fire wood – Anything that will burn, ideally cut into smaller pieces that can fit between the retort and heat shield
  • The Heat Shield: 50-gallon drum
  • The Retort: 6-gallon metal bucket with tight lid. Honestly any metal bucket, barrel, or drum will do as long as it has a tight top. A 30-gallon drum with a removable lid is actually ideal for fitting inside a 50-gallon drum but these things are rarer than hens’ teeth, kind of expensive, and the retort is inherently expendable and will wear out over time.
  • Bricks: Just clay bricks. Can even be broken. Avoid concrete “bricks”, they will degrade very quickly in the fire.
  • A firepit


The Retort:
Drill a hole in the bucket lid, about 3/8. You can drill more than one; I find one is best, though its probably not that important.
The important thing is that you only want holes in the lid. The principle is that the heat cooks the wood inside the retort and releases the volatiles that escape out the hole in the lid. Since there’s no way for oxygen to get in (since there’s only one hole and the volatiles are escaping through it), the wood won’t burn, and turns into charcoal.
If there is a hole anywhere other than the lid, then there is a way for oxygen to get into the retort and the wood will start burning. Note that the lid doesn’t have to seal completely airtight, just mostlytight, as long as there aren’t any holes in the bucket body itself.
The Heat Shield:
Cut the top and bottom off the 50-gallon drum. Keep the rolled lip, it will help reinforce the drum.
The Fire Pit:
If you don’t already have one, or know how to make one, stop reading this now and go educate yourself before you end up in the burn unit.
That’s all! Let’s make some charcoal!


Load your charcoal wood into the retort. You can pack it in there pretty tight, just leave some space around the individual pieces for the gasses to circulate. Give the lid a few good thumps to make sure it’s tight on there.
Place your bricks around your firepit so that you can put the 50-gallon drum over your fire and keep the bottom off the ground (for air circulation)

Making Charcoal

Now the fun part!
Light your fire. Make it strong but not so big that you can’t get the 50-gallon drum over it. This is a good opportunity for your family to enjoy a nice fire and cook some hot dogs, roast marshmallows or whatever. You can get down to business once everyone’s done having fun.
Then put the 50-gallon drum over it. Toss a couple pieces of wood in there to keep it going and build up a good bed of coals.
Once you have a strong bed of coals, lower the retort down into the drum, onto the fire. BE CAREFUL! YOU ARE REACHING INTO A FIRE! Use tools, welding gloves, or whatever other thing you need to keep your friends from laughing at your burn scars. Make sure your retort is stable. The last thing you want is for your retort to be perched on a log that collapses and tips the whole thing over, sending red hot metal and burning logs rolling down your hill. Trust me on this one.
Now, toss some more logs into the drum. Ideally you want skinnier logs that will fit between the wall of the drum and the retort.
What you’ve now built is a giant rocket stove with your retort in the middle. If you have a good bed of coals, the fire should take off pretty quickly and it will burn hot and clean. Soon you should see a plume of smoke coming out of the hole(s) in the retort lid, and when the fire gets big and hot enough, that plume of smoke will turn into a jet of fire and start to roar like a itty bitty jet engine.
This will go on for a while. Keep feeding logs into the top of the drum. Keep an eye on the retort and make sure it doesn’t tip over or lose its lid. Eventually, that jet on the retort lid will stop, and then you know that you have cooked off all the volatiles and your retort is full of charcoal. The time this takes will vary widely depending on the density of wood, how tightly packed the retort is, how hot the fire is, and how much moisture is in the wood.
Once the jet (or smoke) stops, just let the fire burn down. Don’t add more wood. I’ll leave it up to your judgement and safety threshold as to whether you want to bank the fire, get out the hose, or something in between.
Whatever you do, DO NOT open the retort. If you pick it up, you will see how light its gotten and just be dying to pop it open and see. Don’t. That charcoal inside may be hot enough to catch fire and the only reason it hasn’t is because there’s no oxygen. Guess what happens when you open it? I repeat: DO NOT OPEN THE RETORT. Put it aside and wait until tomorrow.

The Next Day

Once your retort has cooled (probably the next morning), then feel free to open it up. Congratulations! If you did it right, you now have a 6-gallon bucket full of high-quality lump charcoal. You will see that bucket is A LOT lighter, and maybe only 2/3 as full as it was when you started. This is normal. Be absolutely sure it’s cooled off, and add it to your stockpile of charcoal.
If your charcoal hasn’t cooled off, there’s a real chance that once you remove the lid and expose it to oxygen, it will catch fire. Remember, this is lump charcoal, not briquette, and it catches fire extra easy and burns without smoke or flame and often with very little ash. Toss one tiny ember in your charcoal stockpile and you’ll lose all of it.
You may well find a number of pieces of wood that are not fully converted to charcoal and are still normal wood or somewhere in between. This is normal. Just keep those to the side and toss them in for the next batch.
If you remove the lid and find a bucket that’s full of ashes and a lot less charcoal than you’d expect…And you have an air leak somewhere. Instead of cooking into charcoal, oxygen was getting in somehow and burning your wood inside the retort.

Well, that’s it. Enjoy, and be safe!

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DIY Cooler (Part 4) Analysis

Flex Seal:

  • Pros
    • White. Smooth(-ish) surface. Looks like it would be easy to clean
    • Food safe, so in theory you could drink the meltwater as long as it wasn’t fouled by whatever else you had in there
    • Cheaper, though maybe not so much if you had to add more layers for durability
    • Easily repaired
    • Easier to ensure is water-tight
    • Good thermal performance. Thermally equivalent to Line-X
  • Cons
    • Stinks when drying. Long application time (each surface has to be horizontal until set up or it will run
    • Two coats are substantially less durable than Line-X or a MIE cooler


  • Pros:
    • Extremely durable. Looks nigh-indestructable
    • Good thermal performance. Thermally equivalent to Flex-Seal
    • Application is quick (by others), nearly instant dry time
    • FDA approved for “incidental food contact” and potable water
  • Cons:
    • More expensive than Flex-seal
    • Granulated surface may be harder to clean
    • Need extra attention to ensure surfaces will spray water-tight (tape on joints?)
    • Thickness of spray may be inconsistent and need trimming for final fit
    • Overspray may be a problem on finished product. Recommend delaying finishing of box to allow for sanding if necessary
    • Base color is black. Think they can probably do white or other colors, but not sure of cost difference


On almost all counts, Line-X is at least equivalent to Flex-Seal, and Line-X is clearly superior in terms of durability. Most of the cons for Line-X are either acceptable or are easily compensated for. The only situation where Line-X doesn’t beat Flex-Seal is cost. For this experiment, Line-X was maybe about twice as expensive as Flex-Seal. I’m not sure what that cost differential would be when scaled up to a full size box, it may be roughly equivalent. On the whole, though, I suspect that when going through the effort to hand-craft a wooden ice chest, it’s probably worth the extra cost for a fully-assed end product.

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DIY Cooler (Part 3) Results


Cooling Performance Test: Boxes were placed in test area (the basement on a concrete slab) and allowed to acclimatize overnight. 3.5 lbs of ice were put into each box. Environmental temperature was not recorded as it should be constant for all and not relevant to comparative results.  Note: boxes were located near an operating ceramic kiln so air temperatures were quite high for a basement environment.

Durability Test: A full (unopened) can of soda (at refrigerator temperature) was dropped, bottom side down from 36″ into the container (at room temperature)

Test Subject #1 – Flex Seal

Cooling performance: All ice melted in less than 68 hours

Durability: Bottom of can hit at a slight angle and caused 1.5″ semi-circular tear lining, dented insulation beyond

Test Subject #2 – LineX

Cooling Performance: All ice melted in less than 68 hours. Note: Line-x spray was not water-tight and melted ice leaked into container and onto floor. After 24 hours remaining ice was put into a bowl inside the box. Not clear if this affected results. Heat gain due to loss of cold water was probably partially offset by reduced surface contact of ice alone against the inside lining.

Durability: No effect on lining. Slightly dented bottom of can

Control – Plastic Cooler

Cooling Performance: All ice melted in 27 hours

Durability: No effect. Can bounced, almost out of cooler. Suspect that plastic lining may have cracked if can was much heavier or dropped from higher.

Read on…

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DIY Cooler (Part 2) Proof of Concept

How do we test this idea without spending a ton of time and money on making a box that may ultimately be a complete failure?

Cardboard mockups!

Using $1 boxes from a local big box store. We could have used leftover shipping boxes, but for scientific comparison, we needed identically sized boxes. Each, lined with 2″ foil-faced iso insulation.

Test subject #1: “Flex Seal”

This stuff is about $30/pint and it looks like one can will coat about 1.5-2 boxes this size. Note that, despite the label, this is not pourable/dipable. It is too thin to cling to vertical surfaces and gravity will make it run and sag. You must leave it reasonably horizontal for about 12 hours. Both Flex Seal and Plasti Dip are pretty noxious going on but apparently food safe once dry.

Test subject #2: “Line X”

Same box as test subject #1, but we took it to a local Line-X dealer to have them spray it. It ran $40, but I suspect a good chunk of that is labor that would effectively be the same with a larger item. The spray builds up a lot more unpredictably than the flex-seal and I had to cut some of it off to get the lid to fit in. I added a strip of foam weather seal (not shown) to both test subjects.


For testing in part 3, we’ll be using an old MIE cooler for baseline performance

Two tests were performed on each subject, to determine performance and durability.

For performance, each test cooler was filled with ice and set out in the shade, and timed as to how long it took the ice to melt. For durability, a full beer bottle will be dropped from 3′, cap-side down, to determine how well the lining holds up to abuse.

Read on…

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DIY Cooler (Part 1) Introduction

Or: An adventure to find a ice chest what doesn’t look like modern industrial excrement

There’s a certain exciting feeling when you walk into a period camp. Wow, look at this, and look at that! What’s going on over here? It’s like a period movie without all the boils and 90% less dysentery. Know what ruins that feeling? Looking at people cooking over an open fire with a pile of modern brightly colored plastic coolers tossed behind them in a forgotten corner. Is your period camp being ruined by a monster in the corner?


I know, there are lots of ways around this: Going full-period and getting rid of even century-old ice-based food preservation (tell that to the food budget and the horde of starving, picky kids). Painting over the bright colors (so now they look like painted MIE coolers). Putting the MIE inside a tent (where they take up precious dry space and are now super inconvenient to get at).

One of the more typical examples I’ve seen is where people take a modern cooler and build a wooden box around it. Even the best executed examples still look like a plastic cooler inside a wooden box. And if you’re already going to the trouble to make a wooden box, is there a way to kick it up a notch?

Its really not that big a deal to make a wooden box and line it with insulation. But that exposed insulation is 1) not durable and would get chewed up right quick and 2) not watertight, all that melting ice is going to make a big mess of your wooden box. Hand-vacuum forming a deep plastic liner seems like a royal pain and outside the capabilities of most home workshops. Forming a metal liner is even more of a pain and expensive to boot.

But, there is a potential solution! In recent years there has been a great expansion of options for paint-on/spray-on waterproof coatings. Spray-on bedliners, rubberized coatings in a can, all relatively inexpensive and easy to get. But, will it work?

Read on…

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Temperature Controlled Beer Box

I have “wisely” decided to bend my 20 years of on-and-off winemaking experience towards brewing beer; on one hand, starting simple by using extract-only recipes, but also skipping the whole bottle conditioning mess and going straight to forced carbonation. This seems simpler to me, having dealt for decades for sediment in wine bottles and wishing to not do any of that with beer. Also, experiences with others’ home-brewed beer have somewhat discouraged me from trying beer…If I want a beer, I just want a beer…Not a beer with special pouring instructions. Hence: forced carbonation.

As I’ve learned, forced carbonation works best if the beer and CO2 are kept cold. Now, having a family and right after hunting season, there’s not nearly enough room or family tolerance for emptying the fridge in order to stuff a keg in there. I could always just put it outside, but that’s not exactly a recipe for consistent temperature, and only really practical for 3-4 months out of the year. A separate device specifically for this seems like the best solution to this plan that doesn’t involve emptying the kitchen fridge. Now if we’re going through the bother of making a device that can cool a keg-sized object, if we add a little more technology so it can controls both heating and cooling, then we can use this device anywhere, any time of year, and not only for carbonating but also controlling fermentation temps, and even chilling kegs for serving. Yeah? Follow where I’m going?

Something like this has got to cost a fortune, right? Well, a few hundred, if you go out and buy some commercial unit. I don’t even know if I’m going to like making beer, so let’s keep it under $100.


Used small chest freezer from Craigslist: $40

Dual-acting temperature controller: $35

Heat lamp:$12

Lamp socket, lamp cord and other random bits from the shed

The rest is easy. Drill holes in the lid to accommodate the cord and mounting screws for the light socket and wire it up. The inside lid of this freezer was only thin plastic and wouldn’t hold the socket on its own with screws , so I used 3″ #10 bolts all the way through the lid. If the outside of your freezer is sheet metal, make sure to deburr the edges, especially where the heater cord comes through, you wouldn’t want those sharp edges cutting into the cord and shorting it out.

Tighten down the socket, add the IR heat lamp, find a convenient place to put the temperature probe. Legend has it that the best place for the sensor is right in the middle. I figure this is good enough, as long as you’re not expecting temperature control down to the individual degree.

And look! It fits a 5 gallon corny keg perfectly. Actually, it looks like it might fit three kegs and a CO2 cylinder!

Close the lid, plug the freezer and lamp cord into the temperature controller. Add some double stick tape and cable management to tidy things up and Bob’s your uncle.

There you have it: for less than $90, a temperature controlled box, good for fermenting your creation of choice, carbonating your drinky-drink, curing your homemade sausages, warming a metric ton of hotdog buns, the possibilities are endless!

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