Let's first start of by saying that fire eating in dangerous. In addition to getting yourself burned, or setting something on fire, as Penn and Teller pointed out, you're slowly poisoning yourself as you do this. Fire eating is different from fire handling, where you can safely pass through or hold flames without any serious damage.

The dangers are real. The flames radiate heat, the torch itself (which is often a metal rod) gets quite hot, and most liquids that burn aren't good for you to consume. Inhaling with fire near your mouth will get you hurt. Even something as simple as wind can throw a flame where it can do damage, such as burning skin, toastinng hair, or igniting clothes. Surprisingly, lip protection can itself be flamable.

What do people use as fuel? Kerosene, lamp and candle oil, are favorites lighter fluid. Alcohols, gasoline, and paint thinner can also work, but are even more toxic.

What you see is a healthy dose of fuel put on the torch, and then the performer shaking the excess off so it doesn't drip or run down the handle. Torches are carefully constructed for this purpose, and there are special handling techniques for extinguishing them. "Eating" fire is actually about covertly exhaling as you close your mouth to put out the flame, but never touching the metal torch with your lips or other soft tissue. To do it right requires special positioning of the head. The heat is real, and the tongue must always be wet.

While you may think "eating" fire is the most dangerous part of the act, the real danger is a tunnel blast of fire from the mouth. The objective is to spray a fine atomized mist over and beyond a lit touch that's away from your face. However, if the spraying technique isn't perfected, two very bad things can happen. One, globs of lit fuel can go where you don't want them. Two, the fire can come back at you, igniting your face.

Learning to do this art requires a lot of practice and control without the torches lit. It requires a strong working practical knowledge of the fuel you're using and how to extinguish flames. And, it also requires a good tolerance to pain, as yes, even the really good performers get burned during a performance; as professionals, they'll suck it up, move on, and deal with the injury shortly. What you don't see is that there usually is an assistant standing by with a fire extinguisher and medical aid.

This is not something you should try yourself, especially alone.

Fire Eating Resources

A good manual of instruction is called Fire Eating by Benjamin Garth, but get the revised edition, ISBN 0-917643-12-7.

Original

Revised