WD-40 is the trademark of a widely used penetrating oil (cleaner, lubricant and anti-corrosive solution) spray. It was developed in 1953 by Norm Larsen (then working for the Rocket Chemical Company) to eliminate water and prevent corrosion on electrical circuitry. It also has many household uses.
WD-40 stands for "Water Displacement, 40th attempt", a name which came from Larsen's laboratory notebook. Larsen was attempting to concoct a formula to prevent corrosion by displacing water, and arrived at the formula on his 40th try.[1] A common myth is that "WD" stands for "war department".
It 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.

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