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This article is about the lubricant. For the company that makes it, see WD-40 Company. For the biomolecular structure, see WD40 repeat.
WD-40 Company logo.png
WD-40 Smart Straw.JPG
WD-40 with Smart Straw
Product type Penetrating oil
Owner WD-40 Company
Country San Diego, California, United States
Introduced 1953; 64 years ago (1953)
Website www.wd40.com
WD-40 spray can from Germany

WD-40 is the trademark name of a penetrating oil and water-displacing spray. The spray is manufactured by the San Diego, California–based WD-40 Company.[1]


WD-40 was developed in 1953 by Iver Norman Lawson[2] in San Diego, California. "WD-40" is abbreviated from the term "Water Displacement, 40th formula", suggesting it was the result of Larsen's 40th attempt to create the product.[1] The spray, composed of various hydrocarbons, was originally designed to be used by Convair to protect the outer skin and, more importantly, the paper-thin balloon tanks of the Atlas missile from rust and corrosion.[3][4] These stainless steel fuel tanks were so fragile that when empty they had to be kept inflated with nitrogen to prevent them from collapsing. WD-40 was later found to have many household uses[1] and was made available to consumers in San Diego in 1958.[3]


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.[5] This 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.[5]

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

Due to its 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.[6]


WD-40's formula is a trade secret. To avoid disclosing its composition, the product was not patented in 1953, and the window of opportunity for patenting it has long since closed.[4] WD-40's main ingredients as supplied in aerosol cans, according to 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.[7]
  • <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 German version of the mandatory EU safety sheet lists the following safety-relevant ingredients:

It warns of the product's high flammability and the risk of irritation to human skin when repeatedly exposed to WD-40. Nitrile rubber gloves and safety glasses should be worn (ordinary rubber disintegrates if exposed to petroleum products). It also mentions that water is unsuitable for extinguishing burning WD-40.

In 2009, Wired published an article with the results of gas chromatography and mass spectroscopy tests on WD-40, claiming that its ingredients make it resistant to freezing.[8]


  1. ^ a b c "Q&A WD-40 CEO Garry Ridge explains company's slick success". latimes.com. 2015-07-30. Retrieved 2015-07-30. 
  2. ^ http://www.sandiegohistory.org/sites/default/files/journal/v60-4/v60-4engstrand.pdf
  3. ^ a b "Our History". WD-40. 
  4. ^ a b Martin, Douglas. "John S. Barry, Main Force Behind WD-40, Dies at 84". The New York Times, July 22, 2009.
  5. ^ a b wd-40-multi-use-product-aerosol
  6. ^ What is Honing Oil? Complete Multi-tool Sharpening Kit. Swiss Army Supplies Website. 2011. Retrieved December 8, 2012.
  7. ^ "WD-40 Facts and Myths". wd40.com. Retrieved 24 April 2014. 
  8. ^ Di Justo, Patrick (20 April 2009). "What's Inside WD-40? Superlube's Secret Sauce". Wired. Archived from the original on 1 Jan 2014. Retrieved 24 April 2014. 

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