Hot Feet

Why don’t all firewalkers get burned?

A devotee of Ban Tha Rue runs across hot coals during a night procession at a Vegetarian Festival on October 16, 2007, in Phuket, Thailand.

A man runs across hot coals during the Vegetarian Festival in 2007 in Phuket, Thailand.

Photo by Chumsak Kanoknan/Getty Images.

Twenty-one people were treated for burns after walking across a bed of hot coals at an inspirational event hosted by motivational speaker Tony Robbins in San Jose, Calif., last week. About 6,000 people reportedly participated in the firewalk. Why were most of them not injured?

Because coal isn’t a very good conductor of heat. In other words, though coal can get very hot—usually between 1,000 F and 2,000 F—it can’t transmit the heat to other materials very efficiently. When flesh comes into contact with a heated material that’s a good conductor of heat, such as metal, it usually results in a burn because the metal heats up the flesh quickly. But coal—and especially the ash coating a burning coal—doesn’t conduct heat very well. So when flesh comes into contact with it, the flesh cools down the outer surface of the coal faster than heat can move from below the surface of the coal and sear the flesh, at least initially. It’s the same principle that allows you to stick your hand into a hot oven without getting burned or briefly touch a loaf of bread baking in the oven, even though you’d get burned if you touched the sides of the oven or kept your hand on the loaf for more than a few seconds. (Bread, like coal, is not an efficient thermal conductor.)

That said, there are dangers associated with firewalking: If you stand on a hot coal for too long instead of moving quickly or if there are any bits of metal, wood, or sap (which are better thermal conductors than coal) in the fire, you could get burned. The same is true if a hot piece of coal gets stuck to your foot during the walk. The scope of Robbins’ firewalk in San Jose—6,000 people sharing a dozen 10-foot-long lanes of coals—might have made it more likely for firewalkers to get held up on the coals, increasing their chance of being injured. (Most traditional firewalking rituals involve only one dozen to two dozen people on a single lane of coals.) Also, minor burns and blisters are common results of even successful firewalking.

Many firewalking proponents claim that successful firewalking is the result of either a heightened psychological state or supernatural protection. Robbins has written that “people change their physiology by changing their beliefs,” and one of the burned firewalkers interviewed by the San Jose Mercury News explained his injury by saying that he “didn’t get into the right state.” But physicists and anthropologists who have participated in firewalks deny that any particular state of mind is required for successful firewalking, so long as the coals are properly prepared and you don’t stay in the fire too long.

Firewalking rituals developed independently in Greece, Fiji, India, and other parts of the world. Usually, firewalking functions either as a spiritually transformative experience or as a rite of induction into a religious sect. Firewalking was introduced to the American mainstream in the 1980s by Tolly Burkan, a spiritually minded self-help author and motivational speaker, and has been adopted by Robbins and other motivational speakers who say the method helps people recognize their full potential.

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Explainer thanks Loring M. Danforth, author of Firewalking and Religious Healing and a professor of anthropology at Bates College.

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