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TLUD Ash Issue. Maybe.


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So, I made a 1 gallon TLUD from a paint can, the bottom of a coffee can, and two 4" soup cans as the stack. I punched about twelve 1/4" holes in the bottom of the paint can, and about 8 holes in the cut-off bottom of the coffee can, which sits upside down on top of the paint can. The soup cans are wired together and are wired to the top of the coffee can part. This forms the stack assembly.


I fill the paint can with red cedar pet bedding, compressed ever so slightly as I'm adding it, spray the top of the bedding with a solvent spray, set the stack assembly on top of it, and light it through one of the eight holes in the coffee can part. The flame goes out in about 15 minutes, but the trouble is, by the time I can pick the can up, transfer it to its cooling pad, and pop the lid on, the edges of the individual shavings begin to turn white with ash. Is this a problem that needs to be addressed or should I just use the product the way it is?


Also, I've been rubbing the charcoal through a 15 mesh kitchen sieve into a storage bucket. The hope is that I can avoid grinding the charcoal to airfloat and just use this -15 mesh product to make BP since the charcoal itself is so fragile, just like newsprint charcoal. I will have a much larger, more efficient mill soon, so that should help.






Edited by Wiley
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I did hear of someone doing likewise for charcoal and giving it a quick mill then passing it over about 400 - 600 mesh. What fell through was grey and ash, what passed over was charcoal black.

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The 4th photo above shows the flecks of ash in the freshly cooked and cooled coal. The last photo shows what the product looks like after rubbing it through a kitchen sieve. I appologize for the inverted images, but windows 8 doesn't offer the option of flipping them.


This is a picture of the cooling pad. It's a piece of "cool wool" used in Quadrfire woodstoves. I place the still-hot cooker on the pad, remove the stack assembly, pop the paint can lid into place, and put that upright paver on top of the whole thing.


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You can pull the chimney a few minutes early and start moving it while it is still cooking.

If you can find a 5-gallon bucket with a solid lid you could drop the entire paint can

inside the 5-gallon bucket and seal the lid on top to stop the air supply. There will be

a little air on the inside of the 5-gallon can, but as soon as the oxygen is consumed by

the cooking charcoal it will go out. opening the lid too soon could start the charcoal

cooking again if it is still hot.


When using 1-gallon cans, I used to have a bucket of sand which I would set the gallon can

into after it was done cooking. I would pile sand around the bottom of the can several inches

deep and seal a solid lid on top. The trick to reducing ash in the charcoal is stopping the

cook process quickly and stopping the supply of air/oxygen to the charcoal.

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  • 2 months later...

I'm also having the white ash problem with my newly made super cheapo TLUD. I just used an old coffee can, punched holes in the bottom and then around the side about 3/4 of the way up. I fill it with cedar chips light and when the flames go out, I place it on flat cement and cover with a wet rag. My problem is that while the flames are still going (clearly starting at the top vent holes in jet like fashion) the chips are already starting to turn to white ash on the edges. Is this just the result of using such a simple design or should I pull it before the flames are out? Thanks


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A little ash is not a problem, you are just loosing the potential amount of charcoal you could produce.

You really need to come up with a better process to shut the air flow off to the coals when

it is close to finishing the cook. A pair of pliers can be used to pull the hot chimney from your can.

With the holes on the side of the can there is no way to seal the combustion air from your burning charcoal.

If you need more holes in the can add them to the bottom, and set the can on a couple of rails to increase

air flow to the bottom holes.

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  • 4 weeks later...

I see this is a bit old, but it sounds like you guys are deviating from the designs that are known to work.


You don't want holes on the side of the can nor on the top of the lid. This just lets air in so the charcoal can burn with this excess oxygen and create ash.


The only holes you want in addition to the holes on the bottom are holes in the side of the chimney a few inches above the lid, and even these aren't necessary. They allow oxygen into the chimney, away from the charcoal, to mix with the smoke coming up so it can burn up the particulates that the smoke consists of. If you don't add the chimney holes it only results in much of the smoke not being consumed by flame. This isn't a problem unless you don't want the smoke which may be bothersome to some or alert others of a fire and your activities.


If you follow a design that others have shared and quickly extinguish the flame like others have described above, most of your ash will not be produced. Like most things in pyrotechnics, you will have the most success following the lead of others and the methods that have been proven reliable. Not only will things work better but you will also be more safe in an inherently dangerous hobby.


Just my 2 cents worth.

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The holes around the base or collar of the flue stack allows the gases cooking out of the wood to burn which increases the heat in the chimney flue stack which increases the speed of the exiting flue gases, which in turn increases the "draft" on the TLUD cooking chamber. If you don't have enough draft on your TLUD cooker your wood fire can extinguish itself easily. The draft on the cooking chamber is a negative pressure which draws combustion air through the bottom holes and maintains a steady burn rate of the wood, slowly turning it into charcoal at a low temperature.

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Or if the flame is going out then you can add holes to the bottom. There's more than one way to skin a cat as I tried it both ways with the above observations and no premature extinguished fires. Regardless, you don't want holes going into the combustion area above the flame front which was the main point.


I have also used a second can the same size as the cooking chamber effectively making it twice as tall at the same diameter with no additional holes. This would greatly decrease the exit velocity (no chimney holes, much more exit area) yet it makes perfect charcoal. In fact my friend that brought the TLUD to the pyro world used this setup and tested it and the charcoal it produced for ten months before sharing it with FPAG where it then eventually spread to other pyros.


There are still plenty of TLUDs of this design in use and most of the builders in the guild had the design in use a year or two before being discussed on forums. The only issue is it doesn't do well in high wind and needs a shield of some sort if it's a windy day. And I have never seen one go out because of insufficient "draft".


How long did you run your TLUD without chimney holes?


YMMV, but this is my real world experience.

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If you can make it work that's all that counts.

The original TLUD cookers were designed for third world country's to make their own charcoal for cooking and heating. There are a number of websites that discuss the different designs being used around the world for this purpose and which ones work the best for this application. I do use mine in a residential area in my back yard so making sure the smoke is at a minimum is one of my main concerns. I might try a solid stack this winter when everyone stays inside from the colder temps to compare the cook times and charcoal production.

Edited by mikeee
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...punched holes in the bottom and then around the side about 3/4 of the way up.

There are also holes on the side of the top can in your picture. If you are getting ash I would imagine they are suspect. I have made and seen a lot of charcoal made and have never seen ash. If you are adding holes to help burn off the smoke it should be up the chimney where there is no possibility of swirling gases introducing oxygen around the charcoal.


Granted, I use wood splits and not thin shavings. I don't know what you are using either but maybe the shavings quickly get some ash in the few moments that you are shutting it down and will be there regardless of the design.


I'm just trying to help. If you are satisfied and it works well then keep doing what you're doing.


Hopefully my knee heals up quickly and I can go back to doing stuff in the shop with the occasional lurking instead of being stuck tapping these keys for a fix of pyro.

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