Saturday Morning Science Experiment: Flour On Fire

Blow Huge Fireballs with Your Breath!
by WonderHowTo

Flour is not as innocuous as it may seem. Like other carbohydrates, it's really just a tiny chain of sugars at heart. And (as anyone who's ever made s'mores knows) sugar can light up like a dried-out Christmas Tree that's been exposed to an electrical spark. In fact, flour dust is highly explosive. Today's experiment takes advantage of the burnability of flour to create a cool fire-breathing trick.

Thumbnail image courtesy Flickr user pinkmoose, via CC



  1. I did that experiment as a science demonstration for an assembly when I was in the fifth grade. One thing I learned was when you put the tube to your lips, DON’T INHALE.

    After a few minutes of hacking flour out of my lungs, and getting the audience to stop laughing, and refilling the flour, it worked wonderfully.

  2. Anyone who has read Monstrous Regiment knows this! Also that the world is flat and there are some elephants and a turtle involved in carting it around.

  3. Looks like he’s getting a fair bit of flour blowing out of the can hole for the tube, especially when he’s got it in his hand. If that flour were to ignite it would blow right into your face.

  4. WARNING: I did this when I was a kid and burned off nearly all of my eyebrows and all of the hair in the front of my head. It will make a heck of a flame ball so be careful!

  5. Maggie: flour’s flammability has nothing to do with what it’s made of, but rather its surface area. As you increase the surface available to oxidize, ANYTHING becomes flammable–including lead.

    Such was explained by Faraday in the original incarnation of this demo, in which Faraday sets lycopodium powder on fire. The flour is completely INflammable in a pile; highly flammable as a dispersed powder. THAT’S the point of the demo.

      1. “Inflammable means the same thing as flammable”

        In my head I totally heard this in the voice of Dr. Nick (The Simpsons.

  6. Lots of dusts do this – it’s why coal mines were/are so dangerous. Any small explosion stirs up dust that then ignites, and the whole thing rips through the tunnels.

  7. I was in a production of Shakespeare’s The Tempest and afterwards we had our cast party outside around a campfire. Part of the entertainment of the evening was taking a handful of flour and tossing it into the fire. The fire would flare up in a very satisfying magical way. It was very appropriate to the show.

    Finally, someone (it may have been me) had the brilliant idea to have each of us take a handful of flour, stand around the fire, and on the count of three all throw our flour in at the same time. A little nervously, but mostly with excitement, we formed a ring around the campfire and counted down. At this point, my memory becomes very primal and loses all sophistication. My entire field of vision was filled with an expanding wall of fire, and my only real thought was “RUN!”

    A second later, the powerful ambient light in the clearing died down and I was back in reality. I untangled myself from the bench I had stumbled over in my attempt to escape, and looked around at the circle of people all in a similar position to me. We saw no one was hurt and began to laugh. We laughed at our stupidity, and with relief for being alive. It was a wonderful night, and I can thank flour’s delightfully flammable qualities for that.

  8. If I remember correctly from my “try to burn everything in the house at least once” phase, non-dairy creamer works even better. Maybe because of all the oil in it…?

  9. Be careful if you modify this experiment. As described, all you get is a burst of flame. Slightly altered, it’s possible to get a small explosion.

    (Traditional grist mills had to be very careful about what tools they used — wooden rather than metal, generally — as there was often enough dust in the air that a spark could cause the entire mill to flash.)

  10. Most people get a lot of different issues mixed up in fire producing experiments, but basically sugars are collected energy from the sun, in which carbon dioxide is captured by specialized centers in green leaves or colorful algae. This consumes energy that is stored in simple sugars (hydrocarbons) and then assembeled into complex starches. Later these are broken down again as young plants spring forth from starch-rich seeds and tubers. The sugars and starches are very energy rich, Given a good supply of oxygen, the stored energy is quickly released. Nitrogen oxides, like potassium nitrate, which provide much oxygen, can do this, and even can be used with sugars as rocket fuel. Direct nitrogenation of sugars can also provide powerful explosives. Finally, the higher the surface area the faster the oxygen will combine with even simple sugars, or carbo dusts will vastly accelerating oxidation and accompanying heat. The Japanese thought the first nuclear bomb was sfinely divided aluminium dust.
    PLEASE don’t experiment with these “tricks”. They can get out of control, especially temperature,easiy.Miam

  11. As a teenage firebug, I would simply throw a handful of flour into the air, then stick a firebrand into the column of flour. Whoosh!

  12. As a kid, we used to grab packets of non-dairy creamer from the coffee shop and just pour it out over a lighter or a match. We made some GREAT fireballs. When camping, we’d bring a huge container of non-dairy creamer and toss it over the campfire. We got kicked out of summer camp once when a counselor walked buy right as we made a fifteen foot tall fireball.

  13. Sawdust Cannon

    What you graduate to when this proves to be too small scale. Dust explosions are nasty whether it be a coal mine, flour mill or plywood sander section of a plywood mill. A grain silo can go off with pretty devestating effect.

    It’s also why you need to run a bare ground wire through your plastic ducting in any sawdust collecting equipment, the friction produced static electricity starts arcing over in a beautifully arranged fuel/air mixture.

  14. Yes, I remember Mr. Wizard. David Letterman also did this over 15 years ago on TV. This Saturday morning science experiment would make sense if Boing Boing’s audience were 7-year-old males. Which, thankfully, it isn’t. So why post something so elementary? Oh. By the way. Finely ground particulate matter explodes when presented with flame and oxygen. Duh.

    1. Why post? Because it’s a cute and easy-to-set-up demo that might be useful for getting kids interested in science… and because it illustrates how to do something slightly dangerous moderately safely, which is also a lesson worth learning. (Though I would have used a somewhat longer blowtube.)

      I appreciate the opportunity to collect a few such demos. I expect I’ll have seen many of them before, but variants are interesting. F’rex, the version of this that I was familiar with didn’t use flour, and hence the reaction proceeded a bit differently.

  15. One of my high school science teachers used to do this for Halloween. He’d make a jack-o-lantern and put the tube in the lower back, so the flames would shoot out of the face. It was great. I think he used licopodium powder (flash powder) though. Of course telling us that flour would work also. That man loved blowing stuff up for us.

  16. Good lord. Use a squeeze-bulb, already. Works great. And set it down on something. We used to do this with sawdust, in an empty paint can. Gently pressing the lid on the can would result in a satisfying bang, and flames thrown four or five feet up.

  17. This guy is a wimp! Years ago, David Letterman had a scientist (a physicist from New York University, as I recall) on his show, who set up a very similar demo. When he had Letterman blow “hard” through the tube, the result was similar to the effort on display here. The physicist look unimpressed (like he thought Letterman was a wimp!), and proceeded to show Letterman how it was done. He produced a fireball that was about 12 feet tall and 6 feet in diameter. It was more an explosion than a fire tower. Find a physicist or a trombone player to blow on the fire and see what you get!

  18. As the son of a shop teacher I bristle a bit at the use of a screwdriver to make the hole – use the right tools for the job and do not abuse tools by misusing them. I love the idea of home science and making but is it that hard to suggest you make a decent. relatively clean hole and not promote the misuse of screwdrivers

    1. Of all the nits to pick, I did not expect that to be one of them. :)

      Also, I feel compelled to mention that the cargo of margarine and flour was one of the main reasons the 1999 fire in the Mont Blanc tunnel became as intense as it did after the truck carrying the load caught on fire. Flour and margarine make excellent fuel.

    1. Yeah, they’re more of a medeocre substitue. However, that still makes them generally better than NO goggles OR glasses.

      Personally, I’d use a one or two yard tube and a foot pump. Lung power is for people who don’t have asthma. Putting your face near fire is for idiots.

  19. Copier and Printer toners are a category of dust explosion hazards. Color laser toners can be even more so. The wild randomness of if you get a detonation or nothing at all is why extreme caution in handling some toners becomes important. Some toner vacs tend to have layers of redundant safety features that literally are hidden in the plastic itself. The hoses are conductive, as are the end fittings. The dust filter canister has ground wires molded into the filter media. The motor’s last layer filter often has metal or high carbon bits.

    Well, using some home “soccer mom” vacs to pick up toner has proven a Very Bad Idea. The guilty former co- workers were astonished by the results.

    Flour also might be not smart to use for fire extinguishing. Years ago, a common thing in kitchens was a coffee can of baking soda with a tin foil lid- cheap fire control safer than most things for grease etc fires. Except that an identical can of bread maker flour got put next to our soda can. I grabbed a handful to put out mom’s bacon fire. Professional Pyros would have wept at the beauty of the fireball that blossomed up and out. Luckily we had decent insurance. And all I needed was a shower and change of clothes. Being euphemistic, you know..

  20. Well if you think flour or coffee creamer works, try powdered shortening. As a member of The Pyrotechnics Artists of Texas ( we used to burn up pallet loads of dairy creamer from Costco and Sam’s Club but that quickly became too expensive. Another pyro member found a source for 50lb bags of powdered shortening and it was much less expensive and easier to cleanup unburned residue. Plus you could then make your own instant biscuit/pancake mix with any unused bags. MMMmmm pyro and quick breakfast.

  21. No one else did the thing with the shotgun shells, and drilling through the wad, and refilling with flour, and then taping one of the BBs to the cap? weighting down the end and tossing them in the air?

    we must of been nuts.

  22. This is no surprise to anyone who grew up in the American Midwest. Lots of towns have “grain elevators” and every once in a while one of them blows up because someone accidentally makes a spark among all the grain dust.

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