* Photo: Tim Morris * Aspen

This soft white wood is easy to cultivate: Clusters of aspen trees are often single organisms connected at the root, which sprouts new growth after harvesting. Aspen isn't very flammable, making for a slow-burning, non-fingertip-singeing matchstick.

Potassium Dichromate

This strong oxidizer in the match head is highly combustible. Diamond Brands, the sole US manufacturer of strike-anywhere matches, won't say what it does, preferring to keep the role of K 2 Cr 2 O 7 a secret. Our bet: It accelerates burn rate.

Potassium Chlorate

It's a source of emergency air on planes, submarines, and spacecraft that releases oxygen when heated. When mixed with wax, it makes a plastic explosive. When mixed with sulfur, phosphorus, and the kind of heat you get from, say, friction, it's very unstable.

Phosphorus Sesquisulfide

4 3 P 4 S 3 also ignites easily by friction. It burns itself out instantly after the match is lit but generates enough heat to ignite the aspen shank. Diamond released its patent for P 4 S 3 matches in 1911 so competitors could stop using an extremely dangerous alternative: white phosphorous.

MonoAmmonium Phosphate

A compound found in some dry chemical fire extinguishers, MAP melts at 374 degrees Fahrenheit. Match makers soak the wood with a solution of this stuff to make sure that when you blow the match out, melted MAP smothers any afterglow.

Ground or Powdered Glass

First, it roughens the texture of the match head, helping to create friction wherever you strike it. Second, it melts under fire but cools and fuses quickly when you blow the flame out, keeping ash from falling.

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