Since the early 1930s, workers have worn hard hats for head protection on jobsites. As early as 1933, projects like the Golden Gate bridge — led by head engineer Joseph E Strauss — mandated that all workers wear a helmet, in this case designed by local manufacturer Edward W. Bullard.
Bullard called his first design the Hard-Boiled Hat. He constructed it by alternating layers of canvas and glue, then steaming the stiff canvas to make it temporarily pliable. Next, he glued together overlapping layers of the canvas to form the shell, covered the shell inside and out with water-resistant shellac, and added leather front and rear brims. The Hard-Boiled Hat met the needs of protecting the workers from falling rivets and other small objects. Workers used it on everything from the Hoover Dam to mining projects deep underground.