An onion can help prevent frost buildup on your windshield

Frozen car windshield

There’s an easy way to prevent frost from forming on your car windshield, and it involves a vegetable.

You can rub the inside of an onion over your outer windshield glass to leave a coating that will keep frost from sticking.

The sugar from the onion prevents water from freezing as quickly. The same goes for using a cut potato instead of an onion.


As “Today” explains, the sugar from the onion creates a barrier over the window that includes sugar. That sugar helps break down the ice molecules and speed up the melting process. When you come out in the morning, your windshield will be clear of ice and snow.

Yellow onions

However, sugar doesn’t really melt the ice. What it does is lower water’s freezing point so it stays liquid at a colder temperature.

Sciencing explains that when it’s too cold outside, the molecules in water lose energy and eventually become bound to one another in a crystalline structure. This happens at the freezing point — 32 degrees Fahrenheit. When it reaches this temperature, the molecules don’t have enough energy to escape the electrostatic bonds they exert on one another, so they become “dormant” — and you get ice.

However, the sugar in an onion or potato binds with and creates more space between water molecules. This (like all substances that dissolve in water) helps the molecules overcome those electrostatic bonds that make them solid.

The key thing with the onion or potato method is that it needs to be done before there’s frost on your windows.


But Farmers’ Almanac has some other more “homespun” ideas for deicing your car after it’s already frosted over.

It says a water and vinegar solution can work, but vinegar may be corrosive so you’ll want to be careful. Same goes for pickle juice. Vodka or another alcoholic solution may work as well. Beet juice, which is high in sugar, can also be effective.

Some things you don’t want to put on your windshield include salt, sand or alfalfa meal, more commonly used on roads; these can cause issues to the glass over time.

A professionally made de-icing substance used by road crews is really the most effective. If any bottled windshield wiper fluid is handy you can pour it on your frosted window to speed up the scraping process too.

And some experts say the best method is to simply use a scraper and turn on your front defrost button. Consumer Reports told USA Today that being creative about windshield care and throwing liquids on your car can damage your wipers or paint.

Have you ever used any of these more unusual hacks for keeping the frost off your windshield or getting it off faster?

Holiday & Seasonal, Tips & Advice

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About the Author
Anna Weaver
Anna Weaver is a writer and multimedia journalist from Hawaii. Her two young kids keep her on her toes and hooked on online shopping. Anna’s also a fan of movies, reading, photography, and sharing far too many IG stories about cute dogs and capybaras.

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