People have been scampering across hot coals for thousands of years. A bed of embers can exceed 1000°F, and the world’s hottest firewalk in 1997 actually topped 1750°F—the same temperature used for cremations. But with the right preparation, experts prance across them with barely a blister. Here’s how they do it.
1) Get Wood
A safe walk requires the right coals, usually cherry or maple wood. Hardwoods are excellent insulators, and they’ll protect feet from some of the heat—even when they’re aflame. (That’s why the wooden handle on a saucepan stays cool when you’re cooking.) Cherry or maple embers also glow a daunting red-orange, but they actually don’t burn as hot as other charcoals, like olive or locust woods.
2) Build a Runway
Once the fire has burnt down, rake the coals. This step makes the red-hot landing strip of doom look even more terrifying, but it will actually spread cold charcoal to the surface, adding insulation. Firewalkers also flatten the coals. Patting down a path keeps them from sinking into the sizzling embers, protecting the sensitive tops of your feet.
3) Break Out a Good Book
After making the fire, firewalkers need to kill time for about 20 minutes. Embers that still hold water can transfer heat to feet faster. Letting the coals dry means they won’t sear any soles. Then they sprinkle a thin layer of ash on top. Ash is a terrible heat conductor, and it can block some warmth radiating from the coals.
4) Just Add Water
After waiting for the bed to cool to a balmy 1000°F walkers dip their feet in some water. When liquid meets intense heat, it can form an insulating layer of steam. It’s called the leidenfrost effect, and it’s why you can snuff out a candle’s flame with two wet fingers. The moisture may act as a protective glove for feet.
5) Walk, Don’t Run
Once experts step onto the coals, they walk briskly and don’t stop. Their feet would sink into the ashpit if they run or hard-step. The lighter the stride, the less chance scorching cinders will wedge between their toes. Each step should last half a second or less.
6) Believe in Physics.
Coals may be hot, but they’re terrible at transferring heat. They have a “low thermal capacity.” That is, it takes them relatively long time to bake a walker. (It’s like sticking your hand in an oven set to 400°F. The air feels hot, but it won’t burn you instantly.) As long as they keep moving, each step will absorb very little heat from the embers.