Reflective materials, such as those seen on traffic signs along America’s highways, came about during the Great Depression and have evolved little since inception. The invention was ingenious, rather than genius. Radium, the era’s fashionable element, wasn’t used- nor electric light, or any other of the era’s emerging technology.
Although most of those outside the-know refer to traffic signs as reflective, traffic signs are retroreflective. Retroflection, unlike a mirror, to oversimplify the physics behind mirrors, returns light directly back to its source, such as the headlamps of an automobile. Retroflective surfaces, such as mirrors, reflect light in all directions.
Retroflection was invented by a laborer named Harry Hetzler. Hetzler designed retroreflective tape using small glass beads, during 1939. Hetzler’s Retroflective material appeared on a highway in Minneapolis the same year. Due to his simple invention, Hetzler became a board-member of 3M. However, Hetzler’s retroreflective orange material wasn’t an instant success.
Hetzler was assigned the task of creating a material that possessed a greater visibility, than white or yellow paint, during the night. Hetzler created a retroreflective material with small glass beads, however, Hetzler’s retroreflective tape lost its sticky property in cold weather. Much like Edison’s light bulb, Hetzler’s reflective material came about due to trial and error. Hetzler and 3M abandoned adhering the reflective material directly to the road and affixed it to sheet metal. Moreover, Hetzler and 3M created a retroreflective paint by mixing glass beads and paint, a truly ingenious invention.
Hetzler’s reflective tape remained in use from 1939-1944, unaltered. However, during 1944 3M developed a retroreflective tape with greater reflectivity and weather resistance, this material is still used in retroreflective fabrics, traffic sign, and bicycles. Currently, a myriad of companies produce retroreflective tape, it can be purchased in almost any color. Moreover, there’s an uncounted number of web pages dedicated to reflective tape craft projects.
Few inventions parallel retroreflective materials in simplicity and dependability. It’s true, the material has evolved little since inception, but retroflection is a technology that require no improvement.