WD-40

WD-40: Invented in 1953

Redstone nuclear rocket, low angle view
Rob Atkins/ Photographers choice/ Getty Images

If you've ever used WD-40 to oil up something squeaky in your home, you may have wondered, just what does WD-40 stand for? Well, according to the company that makes WD-40, WD-40 literally stands for
"Water Displacement 40th " attempt. That's the name straight out of the lab book used by the chemist who helped develop WD-40 back in 1953. Norman Larsen  was attempting to concoct a formula to prevent corrosion, a task which is done by displacing water.

Norm's persistence paid off when he perfected the formula for WD-40 on his 40th try.

Rocket Chemical Company

WD-40 was invented by the three founders of the Rocket Chemical Company of San Diego, California. The team of inventors were working on a line of industrial rust-prevention solvents and degreasers for use in the aerospace industry. Today, it is manufactured by the San Diego, California-based WD-40 Company.

WD-40 was first used to protect the outer skin of the Atlas Missile from rust and corrosion. When it was discovered to have many household uses, Larsen repackaged WD-40 into aerosol cans for consumer use and the product was sold to the general public in 1958. In 1969, the Rocket Chemical Company was renamed after its only product WD-40.

Interesting Uses for WD-40

Two of the craziest purposes for WD-40 include a bus driver in Asia who used WD-40 to remove a python snake which had coiled itself around the undercarriage of his bus, and police officers who used WD-40 to remove a naked burglar trapped in an air conditioning vent.

Ingredients

WD-40's main ingredients as supplied in aerosol cans, according to the U.S.  Material Safety Data Sheet information, are:

  • 50% "aliphatic hydrocarbons". The manufacturer's website claims this ratio in the current formulation cannot accurately be described as Stoddard solvent, a similar mixture of hydrocarbons.
  • <25% petroleum base oil. Presumably, a mineral oil or light lubricating oil.
  • 12–18% low vapor pressure aliphatic hydrocarbon. Reduces the liquid's viscosity so that it can be used in aerosols. The hydrocarbon evaporates during application.
  • 2–3% carbon dioxide. A propellant which is now used instead of the original liquefied petroleum gas to reduce WD-40's flammability.
  • <10% inert ingredients.​

The long-term active ingredient is a non-volatile viscous oil which remains on the surface to which it is applied, giving lubrication and protection from moisture.​ The oil is diluted with a volatile hydrocarbon to make a low viscosity fluid which can be aerosolized to penetrate crevices. The volatile hydrocarbon then evaporates, leaving behind the oil. A propellant (originally a low-molecular-weight hydrocarbon, now carbon dioxide) creates pressure in the can to force the liquid through the can's nozzle before evaporating.

Its properties make it useful in both domestic and commercial settings. Typical uses for WD-40 include removing dirt and removing stubborn screws and bolts. It can also be used to loosen stuck zippers and displace moisture.

Due to its lightness (i.e. low viscosity), WD-40 is not always the preferred oil for certain tasks.

Applications that require higher viscosity oils may use motor oils. Those requiring a mid-range oil could use honing oil.

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