How It Works

Question Of The Day: Why does WD-40 stop hinges from squeaking?

WD-40 stands for Water Displacement – 40th Attempt. It was originally designed for preventing corrosion by displacing the water that causes it. It was first used to protect missiles from corrosion and became commercially available in 1958.

WD-40’s ingredients are a secret. The makers avoided revealing its ingredients by not filing for a patent, but it is known to consist of oil suspended in a volatile hydrocarbon. When WD-40 is sprayed, the suspended oil can get into crevices where the hydrocarbon evaporates, leaving behind the oil lubricant. Every surface has some degree of imperfection at the molecular level. The long hydrocarbon chains in oils and grease serve to provide a layer between the two surfaces and help them move over each other easily. WD-40 was not originally designed as a lubricant so it is actually not the best lubricant to use on a fast moving mechanical part like a bicycle chain.

Connor Skates, Science Museum

  • Barry Preston

    WD-40 was invented in 1953 by Norm Larsen founder of the Rocket Chemical Company, San Diego, California
    Is made up from a concentrate called WD Supaconc,solvent,and about 6grams of CO2 gas as a propellent and a flamable resistant, the concentrate is made in Milton Keynes UK at the wd-40 head quarters and it is reputed that only 6 people know what goes in to it the concentrate is brown and smells of caramel when it is cold it goes thick like treacle needs to be heated before it goes into the areosol can so it is usally held in a tank that is heated the concentrate floats on water.