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WD-40 logo.svg
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; 65 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 WD-40 Company based in San Diego, California.[1]


Different sources credit different men with inventing WD-40 formula in 1953 as part of the Rocket Chemical Company (later renamed to WD-40 Company), in San Diego, California; the formula was kept as a trade secret and was never patented.[2]

According to Iris Engstrand, a historian of San Diego and California history at the University of San Diego, Iver Norman Lawson invented the formula,[3] while the WD-40 company website and other books and newspapers credit Norman Larsen.[4][5][2] "WD-40" is abbreviated from the term "Water Displacement, 40th formula", suggesting it was the result of the 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 of the Atlas missile from rust and corrosion.[6][7] This outer skin also functioned as the outer wall of the missile's paper-thin fuel balloon tanks, which 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.[6]

In Engstrand's account, it was Iver Norman Lawson who came up with the water-displacing mixture after working at home, and turned it over to the Rocket Chemical Company for the sum of $500, which today (2018) is about $4,600. It was Norman Larsen, president of the company, who had the idea of packaging it in aerosol cans and marketed it in this way.[3]

It was written up as a new consumer product in 1961.[8] By 1965 it was being used by airlines including Delta and United; United, for example, was using it on fixed and movable joints of their DC-8 and Boeing 720s in maintenance and overhaul.[9] At that time, airlines were using a variant called WD-60 to clean turbines, removing light rust from control lines, and when handling or storing metal parts.[9] By 1969 WD-40 was being marketed to farmers and mechanics in England.[10]

In 2014, WD-40 was inducted into the International Air & Space Hall of Fame at the San Diego Air & Space Museum.[11]


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.[12] 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.[12]

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 a suitable oil for certain tasks. Applications that require higher viscosity oils may use motor oils. Those requiring a mid-range oil could use honing oil.[13]


WD-40's formula is a trade secret, and may have varied over time.[citation needed] To avoid disclosing its composition, the product was not patented in 1953, and the window of opportunity for patenting it has long since closed.[7] 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.[14]
  • <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, showing that the principal components were C9 to C14 alkanes and mineral oil.[15]


  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. ^ a b Martin, Douglas (22 July 2009). "Obituary: John Barry, Popularizer of WD-40, Dies at 84". The New York Times. 
  3. ^ a b Engstrand, Iris H.W. (Fall 2014). "WD-40: San Diego's Marketing Miracle" (PDF). The Journal of San Diego History. 60 (4): 253–270. 
  4. ^ "WD-40 History - History and Timeline". WD-40 Company. Retrieved 10 April 2017. 
  5. ^ Bobby Mercer (March 18, 2011). ManVentions: From Cruise Control to Cordless Drills - Inventions Men Can't Live Without. Adams Media. pp. 181–. ISBN 978-1-4405-1075-5. Retrieved June 28, 2013. 
  6. ^ a b "Our History". WD-40. 
  7. ^ a b Martin, Douglas. "John S. Barry, Main Force Behind WD-40, Dies at 84". The New York Times, July 22, 2009.
  8. ^ Changing Times (pre-1986) 15.5 (May 1, 1961): p 36.
  9. ^ a b "New Materials". Aircraft Engineering and Aerospace Technology. 37 (5): 165–165. May 1965. doi:10.1108/eb034021. 
  10. ^ "New on the Market". Farm & Country (London). January 1969. p. 72. 
  11. ^ Sprekelmeyer, Linda, editor. These We Honor: The International Aerospace Hall of Fame. Donning Co. Publishers, 2006. ISBN 978-1-57864-397-4.
  12. ^ a b wd-40-multi-use-product-aerosol
  13. ^ What is Honing Oil? Archived November 17, 2012, at the Wayback Machine. Complete Multi-tool Sharpening Kit. Swiss Army Supplies Website. 2011. Retrieved December 8, 2012.
  14. ^ "WD-40 Facts and Myths". wd40.com. Retrieved 24 April 2014. 
  15. ^ 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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