Charcoal from twigs...simple, quick and effective without smoke

inspired from chuck whitlock´s flame cap coal making we tried this system in bath tubs …and it works really very well,


Oh wow Giorgio, your timing culd not be better! I was just thinking to throw out the old bathtub out of our summer bathroom. This shuld work way faster thain the barrel method. I hot piles of dry twigs l thod burning on the spot but this is better



hello kristijan, yes, it goes really fast, for a full bath tub- 200 liters- about 1 our or so, i dont looked on the clock. we made two of the long bath tubs in the morning, and there was a little pile , what not enters more, so i used another bath tub the short sitting bath design, half long as the others…what a difference! with the short tub the air cannot enter so good and it needs much more time for charring as with the long tubs…
procedure: a shovel of glowing charcoal from the kitchen stove in the bath tub…
than always twigs on…
til it is full…
some bigger pieces of the last load i raked beside, because needs more time to finish charring…meanwhile i coverd the redy coal with a layer of ash -5 cm high- for stopping air contact…bevore giving the ash on i pressed the glowing coal a bit with the shovel…
also the ash is pressed a bit with the shovel…
at least i cover the bath tub with a metal sheet against wind and rain…
really impressive that there was nearly no smoke, but this depends also on the twigs…they were from winter cut without leaves…twigs a year old…
also the white stuff on the bath tubs keeps up very well, we did last week also, and works so well so this time my son has the camera with him for fotos for the forum…
we must make higher production , the fiat crawler will be more hungry as my other motors…
ciao giorgio


Uploading: IMG_9360.JPG…
this is the charcoal stock container…air umidity cannot enter, how don mannes makes in his little containers… this is the kind of white containers, -1000liters volume, where bevore chemical liquids were inside, easier to find as exotic containers, often used for watering the garden…
we have protected the white plastic with a black foil to protect from sun light…


I need to grab some IBC totes from my work. Every once in a while they are damaged and left out as garbage. They are not food safe chemicals however so I could never use them for watering.

I bet with that black wrapping it absorbs a lot of heat from the sun and evaporates any residual moisture that the charcoal might have.


I see them tanks at the auction all the time 30 to 50 bucks though,-would hold lots of charco-GREAT IDEA.I like that no waiste of branch wood makeing fast clean burn charco. WHAT size branch is big enough to make engine grade size charco,?


I use a round seed spreader for making small branch and twig charcoal and that bath idea is a fantastic way of being able to burn down long branches and twigs with having to cut them up , BUT the ultimate genius of Giorgio’s bathtub system Has to be his dousing idea its just plain simply fantastic pouring sand over the coals so he can harvest it later when cold .
When i use the round seed hopper i wait till it flames out on top and then shovel hot coals into 25 litre drums with loose fitting lids after 30 mins i then tighten lids down till i am ready to use .


cody , the black foil is only for to save the white plastic from sun-corrosion… the container closes hermetic, so no umidity can enter but also not come out…the coal comes in as soon as possible after production, so should be dry as possible for storage…we have the plastic always in places with most possible shade for longer life…
i must always think to doctor görans house-.crows what destroyed his coal storage plastic sacks…whater enters…with this containers less chance for the crows…


kevin, we use all twigs under approximately thumb size also the very fine pieces -what would be to small for motor coal-gives fire and helps charring the other pieces…all thicker branches we use for our stoves…
the bath tub system is like a coal pit, but has the advantage, no stones and earth in the coal, and is mobile, i must not bring the twigs to the tub, but i bring the tub to the piles- nomade coalery system…


dave, no sand, i use ash…is easy to sieve to take away after cooling, the most i take away with a shovel, till i arrive at the coal layer, the rest is than sieved out while doing the coal sieving…
yes, a big advantage is that the whole lenght of the twigs can be burnt…also , if one has big piles of twigs…there is the possibility of the TWIN -TUB system…two bath tubes aside, so laying in the twigs must not be very careful for lenght direction, voluminous fork loads are thrown in the middle of th tubs, and while burning and charring, fall in one or the other tub!!


thanks for clarifying. I was wondering what you were using :slight_smile:

you can do the same thing with just pit, but the bathtub is nicer. It is coated with enamel, like you would have on a stove so it is heat resistant. :slight_smile:


Only old bath tubs are metal enamel and are hard to find these days. I would think you could use a barrel cut down from top to bottom into two long pieces. Use some rocks or bricks on the sides to stablize them. Much lighter then a bath tub too and portable too.


you certainly can. It all related to flame curtain kiln. Which I personally associate with the kon-tiki. You can use a pit, barrel, bathtub, etc. Ideally it has a curve to the sides to allow more material to be put in, but it isn’t strictly necessary.


I have a Kon-Kiln cone shape with a open bottom works great on top of my retort with the bottom grate. Kinda like @Matt is using.


Im not a fan. Its good for biochar but no good for gasifiers. You get a lot of dirth in the charcoal that all turns to slag


Doctor göran… i don’t know… i think “village special” as Tone said are more suitable :smile:
Those containers remind me… i got 5 of them “ibc-toutes” for free some years ago (wish i took a pic of the load on the Chevrolet)
I gave 4 of them away to a friend, and the last one i built a outdoor-bathtub from, i really wish i had keept one or two for storing charcoal in.
Good idea :+1:


I think his system is a bit better then most because he is using ash instead of dirt to stop the fire which doesn’t introduce more dirt. IF the tar and slag are an issue, it can be run through another retort, by the time charred the first time, it is much easier to break up, and will remove a lot of the ash. Then it is also easier to get it up to temp to remove the rest of the tars. Working with gnarly brush is kind of a pain in the butt as pictured in your video with it sticking out all over the place. :slight_smile: Ideally, one would are starting with even chunks of debarked wood for the char, but we don’t live in an ideal world. :slight_smile:


Nice post, Giorgio… I’m also building an “open pit” charcoal retort in the very near future. I personally find it the best overall method.

Some details:

  • Brick-lined, tapered pit about 36-inches deep, 4-foot wide, 8 feet long
  • Sheet metal lid for smothering (hinged or roll on)
  • Exhaust pipe from generator plumbed in to push out remaining O2
  • Fermentation style water seal where lid meets the brick for complete seal

Future vision:

  • The tapered pit uses an auger (bottom center) so I can approach continuous production vs batch
  • Finished char is augered into a sealed container or sorts with exhaust gas to kill any remaining oxidation
  • The “smother lid” becomes more like a 4-inch x 4-foot x 8-foot water or air heater so I can use that (otherwise) wasted energy and hangs over the pit at optimal distance (like a range hood)

Nice work.