Most types of makeup are produced with hydrocarbons--chemicals that burn when in contact with intense heat. Hydrocarbons being a nonstarter, the Army went with less flammable silicones. DEET is flammable, too, weirdly, and the guidelines required a full 35 percent of the paint to be made of the stuff. To sidestep that issue they placed a hydrogel around it, a chemical that's mostly water. The heat from a bomb lasts a mere two seconds, but researchers managed to get the paint to protect for a whopping 15 seconds, so early testing has definitely been successful.