Dr. Wallace Carothers, the head of DuPont’s research division, sought a fiber that stood up to both heat and solvents. During his research, he became the first to synthesize nylon. Originally, DuPont determined that the fiber was best used to replace silk in women's hosiery. The first batch of nylon staple was delivered to a commercial knitting mill under conditions of extreme secrecy—the chemist carrying the staple slept with it on his person on the overnight train ride to the mill. In the first year of production, DuPont sold 64 million pairs of stockings. During World War II production was channeled away from pantyhose and into parachutes and B-29 bomber tires. Following the war, nylon appeared in a wide range of consumer products. Today, it’s used in gear ranging from climbing ropes to jackets to tents.