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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,[1] 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.[1] 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.[1][2] The product first became commercially available on store shelves in San Diego in 1958.[1]
The long term active ingredient is a non-volatile, viscous oil which remains on the surface, providing lubrication and protection from moisture. This is diluted with a volatile hydrocarbon to give a low viscosity fluid which can be sprayed and thus get into crevices. The volatile hydrocarbon then evaporates, leaving the oil behind. A propellant (originally a low-molecular weight hydrocarbon, now carbon dioxide) provides gas pressure in the can to force the liquid through the spray nozzle, then itself diffuses away.[citation needed]
These properties make the product useful in both home and commercial fields; lubricating and loosening joints and hinges, removing dirt and residue, extricating stuck screws and bolts, and preventing rust are common usages. The product also may be useful in removing moisture.
Citation:
WD-40's formula is a trade secret. The product is not patented in order to avoid completely disclosing its ingredients.[2] WD-40's main ingredients, according to U.S. Material Safety Data Sheet information, are:
* 50%: Stoddard solvent (i.e., mineral spirits -- primarily hexane, somewhat similar to kerosene)
* 25%: Liquefied petroleum gas (presumably as a propellant; carbon dioxide is now used instead to reduce WD-40's considerable flammability)
* 15+%: Mineral oil (light lubricating oil)
* 10-%: Inert ingredients
The German version of the mandatory EU safety sheet lists the following safety-relevant ingredients:
* 60-80%: Heavy Naphtha (petroleum product), hydrogen treated
* 1-5%: Carbon dioxide
