Web Date: August 22, 2012
Face Paint Shields Soldiers’ Skin From An Explosion’s Heat
Camouflage makeup is getting a makeover. Chemists from the University of Southern Mississippi, Hattiesburg, have developed paint for the face and hands that can protect soldiers from the extreme temperatures of a bomb blast.
The greasy face and hand paint soldiers currently use to blend in with their surroundings proves to be a liability if they experience an explosion. “A roadside bomb emits a ballistic thermal blast that exceeds 600 °C,” explained Robert Y. Lochhead, who spearheaded development of the new makeup. “The blast lasts for less than two seconds, but this is sufficient time to cause lethal burns to a person in its path.”
With this in mind, Lochhead and his research group set out to create a makeup that could reflect such searing heat away from the skin. He discussed his progress in a presentation today in the Division of Polymeric Materials: Science & Engineering at the American Chemical Society national meeting in Philadelphia.
Because camouflage makeup needs to be colored, the first challenge was finding pigment particles of the proper size. Conventional makeup pigments fall in the 100 to 500 nm range—too small for reflecting heat. “Lethal ballistic heat waves have wavelengths of 1,000 to 8,000 nm,” Lochhead said. “If pigments were to scatter or reflect these heat waves, the particles would have to be larger than the wavelength of the heat—that is, larger than 10,000 nm.” Lochhead and his colleagues were able to find two pigment manufacturers that were able to assist them in developing pigments of the proper size.
The researchers also needed to find a vehicle, or base, for the paint. Conventional hydrocarbon vehicles absorb a blast’s heat. Because the Si–O bond absorbs just outside the lethal heat range, Lochhead’s group settled on silicone as a vehicle.
Finally, the military requires that all camouflage makeup contain at least 35% of the insect repellent N,N-diethyl-m-toluamide, or DEET. “DEET in this application is more than an insect repellent,” Lochhead said. “It is fuel for the fire.” To overcome this problem, the researchers encapsulated the DEET in a polyacrylate hydrogel. They are currently conducting tests to ensure the encapsulation doesn’t hinder DEET’s insect-repelling properties.
So far, thermal tests indicate the new makeup is able to keep surfaces from reaching 60 °C—the temperature at which skin burns—for 10 to 27 seconds, depending on pigment color. That’s far greater than the four seconds the military requires. The military is currently conducting wear and comfort tests on the paint.
“In developing this technology, Lochhead and colleagues have demonstrated how cosmetic chemists must routinely manage extraordinary complexity to deliver breakthrough products,” commented Michael Fevola, associate director of advanced technologies at Johnson & Johnson. In this case, Fevola said, the researchers had to consider ingredient functions and interactions as well as application, comfort, durability, and stringent thermal performance requirements. “This team was given a tall order to deliver,” he noted.
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