Introduction: Fireproof Carbon Foam From Pyrolysed Bread

Picture of Fireproof Carbon Foam From Pyrolysed Bread

Carbon foam has some very useful properties: It is an excellent thermal insulator.

The fact that it's made from bread adds "much wow!" to a very simple process.

You could conceivably cover you space rocket in these ablative tiles for re-entry. Because Science! NASA! Outer-space! Clickbait!

Step 1: Weld a Steel Box With a Hole in It

Picture of Weld a Steel Box With a Hole in It

You'll need a container that you can heat the ever living tar out of. Literally, we are going to roast the tar out of bread.

The hole is so hot gas can escape and the box doesn't blow up and kill you.

I made my hole threaded so I could add a bolt and let only a tiny amount of gas out through the threads.

I also purged the box with Argon gas. A redundant step; but, belt and suspenders amirite?

I'd leave a chemistry joke here, but all the good ones argon.

Step 2: Roast the Box With a Propane Torch, or Campfire, Until No More Yellow Flames Are Visible

Picture of Roast the Box With a Propane Torch, or Campfire, Until No More Yellow Flames Are Visible

The yellow flames are hot volatile gasses leaving the box. Once the yellow flames die down, you know your bread has been turned to carbon foam.

Step 3: Much Fun! Experiments! So Enjoyment! Very Hyperbole!

I blast the carbon foam with an oxy/acetylene torch and melt aluminum directly on the tile.

Then I checked with a thermocouple how well the tile was insulating from the torch blast.

I also checked the electrical resistance. It is very high! From my previous tinkering with graphite, it has very low resistance. The difference is in the structure of the carbon! More research required...

I also made a vid of this. I'm told it sucks:


ysnipe (author)2016-07-21

I guess I'm missing something... I think I've made this more than a few times already... a couple of times in a toaster oven during a phone call... on a grill when a hamburger bun got left behind... Sorry but this is just burnt bread.... Why go to the trouble of making a steal box to burn it in, a gas grill or toaster oven will do it just as well... Or if you don't want the smells just put in in your oven when you turn the oven on the clean cycle.

Greymase (author)ysnipe2016-07-21

Pyrolizing is the burning in the absence of Oxygen. The Argon doesn't make is special, but it DOES replace the oxygen in the chamber. The oxygen would be burned off pretty quickly in a sealed chamber, but in a toaster, the resupply would lead to a lot of CO2 (where the oxygen mixes with the Carbon in the burn down process) which is very different in behavior than CO2. So this LOOKS like burned bread, and it IS, but in the absence of Oxygen - so it is C, not CO2. "Brown's Gas" is the flammable byproduct that is giving the yellow flames mentioned. I hope that helps.

Udon (author)Greymase2017-10-31

Yeah, I don't think that's Brown's Gas - water that's been electrolyzed into hydrogen and oxygen is referred to by that name.

johnny3h (author)Greymase2017-10-08

I have seen "Brown's Gas" referred to in other posts here, and am compelled to illuminate the error. The gas released in the pyrolization [sp?] process in this 'able has NO relation to Brown's Gas [a stoicametric mixture of Hydrogen and Oxygen resulting from the ELECTROLYSIS OF WATER!].

The gas produced by pyrolization IS NOT Brown's Gas!

Please forgive my misspellings; it's been over 40 years since my last chemistry class.

Greymase (author)johnny3h2017-10-09

Yes! Thanks! I actually was aware of that, but had been reading about Brown's Gas around the time of the comment and was in a hurry and goofed! Thanks for catching it all this time later, johnny3h!

Science...if we are wrong, we admit it!

tonymengela (author)ysnipe2016-07-21

not the same thing, If you notice he used argon in the heating process, it changes the bread into something else entirely

Greymase (author)tonymengela2017-10-09

I don't think it is any magic property of Argon in particular, as much as it is that it replaces the oxygen in the container. The paint can with the hole works because the outgassing of the bread and early burning likely burns out the oxygen and creates positive pressure keeping a sufficient amount out to cause the bread to burn with oxygen...same as making char cloth or biochar

danrulz98 (author)ysnipe2016-07-21

Yes, its bread with everything but the carbon burned out of it, you could make it in a toaster or oven as well. AvE just likes going overkill ;)

PitStoP (author)2016-07-21

How long will the foam/burnt toast will hold up under the high heat? I'm in the process of building an pizza oven and was wondering if this will work for insulating the dome. Thanks for the Instructable.

electricaveman (author)PitStoP2017-10-26

Well, I left some charcoal on top of a wood heater one year in a mortar (a ceramic bowl used for grinding). By the end of the winter the carbon that was ground into the ceramic had completely disappeared. The top of the heater stayed above 400 f for about 7 months.

SebaM1 (author)PitStoP2016-07-25

I was thinking of doing the same thing with nicrome wires andwas wondering if I could use the same nicrome wires to burn the bread

Ryan Hebron (author)2016-08-08

I have allways wandered what AVE stood for.

Its in his youtube channel URL

billgeo (author)Ryan Hebron2016-11-13

Me too, now we know!

johnny3h (author)2017-10-08

This same process can be accomplished much more simply with a clean paint can and lid, with a nail-hole punched in it, and burned in a small fire in the yard!

bitterbug (author)2017-07-26

Just finished making some in a paint can, but it mostly curled up as it shrank. But this was fresh from the bag. For the second run I'm putting slices in the dehydrator to create flat, dry pieces before they even go into the can :D



rhgrafix (author)2016-11-18

I've made this in my toaster before, accidentally, I must tell my girlfriend that I was making carbon foam, she will be impressed!


gh426 (author)2016-11-01

Isn't this also BIO-CHAR?? I see folks cooking very dry wood, supposedly any organic schmoo will work, and they get pitch, tar, etc seperated from it, vs burning it off and viola edible BIO CHAR, they also grind it up add worm casings, flour etc and make rich dirt with for to make Veggies / fruits

hugbear (author)2016-07-25

So the pyrolisis removes all the organic components, leaving behind only minerals and carbon - making sure the carbon does not combine with oxygen at high temperature and burn. My question is: once the foam is removed from the container and placed in free air, what keeps the carbon from burning with the oxygen in the atmosphere when exposed to a flame?

LazyH (author)hugbear2016-08-29

I may be wrong about this so anyone else correct me if I am, but the carbon foam will eventually burn away, it is simply and effect of the insulating properties that only allow the tiniest portion of the surface of the material to get hot enough to actually combine with oxygen. From what I understand this is like aerogel, being made of glass foam you'd think it would melt instantly under heat from a torch but there are several demos of aerogel insulating things like crayons and flowers from a direct blast from a torch without any visible affect on the aerogel, simply because such a small part of the surface was affected by the torch. Heat it long enough and the bread will burn and the glass will melt, it's just really slow.

hugbear (author)LazyH2016-08-29

Makes sense!

BrandonD80 (author)2016-07-18

Great idea

BrandonD80 (author)BrandonD802016-07-18

Could i use a Mapp gas torch and something like a coffee can to make? I dont have oxy/acetylene or a welder.

I believe he uses a tiger torch running on propane. I would guess you can use any metal container as long as you purge out the air with an inert gas and don't melt the container. But maybe AvE has more insight to help you.

LazyH (author)cerberustugowar2016-08-29

You don't even need to purge the oxygen, it will usually burn away before it starts affecting the carbon, but that's if you have a mostly sealed container with a small vent for gasses to escape. I used to make small chunks of charcoal and charwool from fabric and branches just wrapped in aluminum foil and tossed in a campfire. It's impossible for the foil to completely seal what's inside and what little oxygen there is will get either pushed out with the browns gasses or will burn with the browns gas and become inert to the carbon that remains. I use to take a 20 gallon steel drum and will it with wood from out at the farm and do the same thing, the lid wouldn't completely seal it so I had a working vent, but it kept the oxygen out long enough to completely pyrolize the whole thing, adding argon just adds a bit extra insurance to make sure it all goes right.

Paul 2 (author)2016-07-22

I make a lot of carbon for use as a fuel , street name is charcoal. For small batches I use a cast iron dutch oven on my gas grill. Carbon does not transmit heat very well but will burn (combine with oxygen) in air in the presents of heat. The advantage of carbon over hydrocarbon is a cleaner burn. Only carbon and oxygen.Carbon in it's different forms has many uses. Thank you for your indestructible.

LazyH (author)Paul 22016-08-29

from what I understand both can have an equally clean burn, but because hydrocarbons are typically fluid in nature (gas like propane or liquid like octane) they will be able to burn more efficiently (more completely) due to better mixing with the oxygen in the air and reducing the chances of co and soot/ash. Of course there is almost never any PURE hydrocarbons or carbon to burn, hence why you have ash left after a charcoal burn, and it also depends on the environment of the burn too (insulating container, oxygen rich or lean atmosphere, high air currents, etc.). I've never had any residue of any kind left after a propane burn for my forge or metal casting, but charcoal will always leave some kind of ash or residue, especially if its not homemade like ours is.

AlejandroS101 (author)2016-08-27

NIce work :)

You had soldered the box. ¿Do you have tryed to press a flat cover against the box with a screw press? In this way you will not need the treaded hole.

Steinrik (author)2016-07-29

I believe this is the inspiration for this experiment:

which points to:

SebaM1 (author)2016-07-25

What temperature would you need to reach to burn all the organic components? I was thinking of using nicrome wires to do it, but I cant go above 900C. Would that be enough?

inmarket (author)2016-07-21

I wonder if you could use backing soda and vinegar in the bottom first to fill the container with CO2. That removes the oxygen too as CO2 is heavier than air. That would be cheaper than Argon and would enable other non-welding heat sources.

kevinrivero (author)inmarket2016-07-24

that's a great idea. any idea how to isolate the baking soda/vinegar mixture from the bread? I wonder if it'd even matter. What exactly do you mean by enabling other non-welding heat sources?

Starsword7 (author)inmarket2016-07-22

good idea!

astrong0 (author)2016-07-23

I bet a small piece of chicken wire on top of the bread would force it to carburize flat. I might need a piece of bread for my forge.

Starsword7 (author)2016-07-22

great instructable!

how strong is the bread?

does it still crumble?

brodie (author)2016-07-22

As I understand it this is the exact same process used to make charcoal from wood.

So is it the structure of the bread that gives it the inability to burn, and the thermal resistivity?

oldmanbreadboard (author)2016-07-22

You Pb us down the wrong path with the Argon joke. I hurt myself when I put my Neon a Copper's car. He put the Iron's on me but as an Native American Indium might say, "Me hope it Helium soon." Gosh that is bad, but it is early.

RafaelGAlmeira (author)2016-07-22

Are the thermal properties related to the physical structural arrangement of the bread? Would it work the same if it is crushed?

It's a two-fold. 1. Void spaces between the front and the back of the pyrolyzed bread limit the heat transfer to virtually nothing. 2. The pyrolization process leaves mostly ash which is non-combustible and allows for the voids to stay in place.

clazman (author)2016-07-21

find this an interesting process, to say the least. I will need to do some research.
I have always wondered about the manufacturing process carbon fiber and its tremendous

In this process , eliminating oxygen, the “normal” oxidizer, is interesting.
For example, in the stoichiometric combustion of a hydrocarbon only CO2
and H2O are the products. All other products are the result of
incomplete combustion or impurities, nitrogen being one.

In this process the result is quite different. CO2 and H2O
do not exist, save for oxygen existing in the bread making components.

VincentV37 (author)2016-07-21

Some mornings i Wake up, then i Get Up....then i Light Myself on Fire ! The Emt's Arrive and take me to Hospital.....where they Tend to my Burn wounds, as i Read the Paper. This Happens more Often than i care for.....But's a Living ! LOL!

VincentV37 (author)VincentV372016-07-21

It is Completely a "Kid's in the Hall/ Rant and Skit" But Still Funny many Years After the Fact !

mrandle (author)2016-07-21

I saw something like this on a science site a few weeks back and saw that they can change the properties by baking their own bread and tweaking the recipe. Basically if you increase the yeast, the holes get bigger, which makes it more "foamy" when you pyrosize it. Where can you get your hands on argon a welding supply store?

sWillyPs (author)2016-07-21

Nice. You should try this with wool yarn. :)

Years ago I worked for a company that made carbon fiber, graphite, and boron products.

Guess what the exhaust cone of a missile motor starts out as?

dkcoles (author)2016-07-21

I do this everytime I try to make toast and was surprised by the mechanical properties. I like your setup more, it is less likely to upset the roommates or require large amounts of ventilation in my kitchen

jferva (author)2016-07-21

wondering what would happen if, instead of bread, the same process is applied to flour... Any ideas? Anyone?


Rebuildboy (author)2016-07-21

What's really interesting is that 13 years ago our then 3 year old some discovered carbon foam, only we didn't realise what he had done. His method was to put bread in the microwave for 99 minutes and 99 seconds. I'm not sure at what point we stopped the microwave, I would guess at around 45 to 50 minutes gone. My only advice is that do not repeat this experiment in a microwave that you wish to use for anything else ever again, the smell will never ever go away. I just wish that we had known then what he had discovered

rharris23 (author)2016-07-21

This is the best thing since sliced bread.

yoshyz (author)2016-07-20


great sens of humor .

About This Instructable




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