WD-40 is the trademark name of a widely-available water-displacing spray developed in 1953 by Norm Larsen, founder of the Rocket Chemical Company, San Diego, California. It was originally designed to repel water and prevent corrosion, and later was found to have numerous household uses. WD-40 stands for "Water Displacement - 40th Attempt". Larsen was attempting to concoct a formula to prevent corrosion, by displacing the standing water that causes it. In the process, he arrived at a successful formula on his 40th attempt. WD-40 is primarily composed of various hydrocarbons. WD-40 was first used by Convair to protect the outer skin of the Atlas missile from rust and corrosion. The product first became commercially available on store shelves in San Diego in 1958.