From the Handbook of Construction Techniques about in 1960 Keeping a Cool Head After experiencing severe headaches for several days while wearing his metal safety helmet in the hot sun, Ray Vaught, a foreman with E. E. Barber & Sons of Texarkana, Ark., came up with a cool idea to take the heat off his head. He put a 1-ft-square piece of 3/16-in.-thick asbestos inside his helmet as an insulator. The marked difference in temperature between a lined and unlined helmet was clearly evident by touch. By strapping a thermometer inside an asbestos-lined helmet, Ray found that the temperature inside was as much as 20 deg cooler than the temperature outside. It wasnâ€™t long before everyone on the job had adopted his idea for keeping a cool head.