WD-40 is one of those everyday products most people recognize immediately. The blue-and-yellow can can be found in garages, workshops, and homes, usually brought out when a hinge squeaks, a bolt gets stuck, or metal begins to rust. But this familiar household product has a much more surprising history. WD-40 wasn’t originally created for garages or home repairs—it was developed in the 1950s for aerospace technology connected to the Atlas missile program during the Cold War.

The name itself explains how the product came to exist. WD-40 stands for “Water Displacement, 40th formula.” In 1953, the Rocket Chemical Company in San Diego began developing rust-prevention products and degreasers for the aerospace industry. The small company had only three employees, and after 39 unsuccessful attempts, the team finally created the formula that became WD-40. The 40th formula worked, giving the product its famous name.

The reason for developing it was serious. During the Cold War, rockets and missiles had to withstand difficult conditions, and moisture could cause dangerous corrosion to metal surfaces. The company was working on a product that could push water away from metal and help prevent rust, making it useful for protecting important aerospace equipment.

WD-40’s first major industrial customer was Convair, an aerospace contractor involved with the Atlas missile. The product was used to protect the missile’s outer surface from rust and corrosion. As the article puts it, “The same general product that people later sprayed on bicycle chains, garden tools, hinges, and stubborn bolts had an early job protecting the exterior of a missile.”

From protecting Cold War missile hardware, WD-40 eventually became a familiar household maintenance product. Its journey from aerospace technology to the average toolbox makes its history far more interesting than its simple appearance suggests.