Weird as it seems, flammable metal isn't that rare-plasma cutting torches and magnesium photo flashes are two examples I've written about here. But you don't need anything fancy to send metal up in flames. Take a wad of steel wool (extra-fine 0000-grade works best), hold it in a pair of pliers, and light it with an ordinary match.
You won't get a big fireball, but it definitely burns-even faster if you blow on it. Bits of red-hot iron may fall to the ground, so do it outside and watch your feet.
If you can light steel wool with a match, why can't you light a nail? Or a cast-iron pot? It's a question of surface area versus volume. The burning process, which is just rapid oxidation of the metal, has to bring nearby iron to its ignition temperature fast enough to sustain a chain reaction. Thick pieces of iron conduct heat away far too fast for the surface to ever reach the ignition point. But in very thin strands, there's nowhere for the heat to go, and a burning patch can race along the length of wire, converting a whole steel-wool pad into iron oxide-rust-in less than a minute.
There isn't really a practical reason to burn steel wool (unless perhaps you were stuck in the woods with 50 pounds of it and a hot dog). But this form of rapid oxidation is similar to how cutting torches work. If your mom won't let you have one of those, this is the coolest way to watch something that seems unburnable go up in flames.
Lighting Steel Wool
Time: 2 Minutes
Safe | | | | |
Do this experiment outdoors, and always wear appropriate safety gear. Children should not attempt this experiment without adult supervision. Find more on Gray's scientific pursuits at periodictabletable.com and at popsci.com/graymatter.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.