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A Washington Post article on how an aerosol can of dry shampoo blew a hole through the roof of a car in St. Peters, Mo., has been picked up by outlets everywhere. 

In reporting on this story, the Post turned to Bryn Mawr Professor of Chemistry Michelle Francl.

From the Post:

Michelle Francl, a professor of chemistry at Â鶹AV, took a look at the dry shampoo can in question. "It's got propane and butane in it, which are the same things that are in lighters," she said.

The two flammable ingredients are common in aerosol products. They act as propellants to release the product out of the can, Francl said. Hydrofluorocarbon 152A propane, which replaced the now-banned Chlorofluorocarbons, is in there for its dispersal properties. The denatured alcohol, which simply carries the product, is also flammable, Francl said.

"At least if you are transporting butane or a propane tank you know it's dangerous and can take special safety precautions," she said. "This was a seemingly innocent can of dry shampoo."

Francl theorizes that the temperature probably got too hot in the car, which caused the can to explode. "I would not have wanted to be in the car when that happened," Francl said, adding that sharp, flying parts of the can could've been dangerous, in addition to the flammable items inside. "It's like a small explosive device."

Subscribers to the Post can read the article on its website. Others can check it out on a number of sites, including the website.

Department of Chemistry