Simple Ways to De-Ice a Windshield

Gloved hand scraping an icy windshield.

Siarhei Kelnik / EyeEm / Getty Images

There's no need to wait for your car's defroster to warm up to melt the ice on your windshield. You can defrost your windshield much more quickly using a few tricks from science (and, if you want, a bucket of brine).

Use a Salt Water De-Icer

If it's not super cold outside, warm water works well as a quick defroster. You can pour warm water over your windshield and use the wipers to clear it off. If it's really cold outside, however, this will only add another layer of ice to your windshield (best case scenario) or, by creating an extreme temperature difference, cause it to crack (worst case).

Salt water works for the same reason that salt alone works as a de-icing agent. Warm salt water is your best bet. The ions in salt water lower the freezing point of water, causing the ice to melt. After melting, the water will attempt to re-freeze. However, the temperature will need to be colder than 32 degrees Fahrenheit for that to occur. When it comes to de-icing, not all salts are created equal. Normal table salt works well when it isn't too cold out. Road salt, which has a different chemical composition, works better when the temperature is very low. Salt exposure isn't great for your car, though, so keep that in mind. If you use salt water to clear away ice, you will want to clean your car later.

Create Heat on a Frozen Windshield

An even quicker way to melt the ice on your windshield is one you may already know — placing your bare hand against the windshield. This works because (a) your hand is warm and (b) your hand is solid. Warm solids contain more particles per unit area to convey heat to the windshield than warm air alone (because molecules in the air are very far apart). For this reason, any warm solid will de-ice the windshield faster than air. Any warm liquid will de-ice more quickly than air for the same reason.

You don't have to use your hand. The sole of a warm shoe works just as well. So does a warm book, for that matter. The denser the object, the more effective it will be at de-icing a windshield. The heat capacity of the material matters, which is one reason why your hand is such a great defrosting tool.

If it's not too cold out, try using a warm, damp towel on the windshield. If it's bitterly cold, the ice scraper is still your best bet. If you have a garage and live in a warm climate, you can prevent the frost from forming in the first place by parking inside.

You can also use common household chemicals to defrost your windshield. These materials apply freezing point depression to clear the ice. It's a good idea to use your wipers and fluid after you apply them because they can be sticky or corrosive. Of the items listed below, rubbing alcohol is your best bet for fast defrosting without damage:

  • Pickle juice (saltwater brine)
  • Beet juice
  • Kool-Aid (or any other sugary soft drink)
  • Soda (with sugar)
  • Vinegar
  • Rubbing alcohol
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Your Citation
Helmenstine, Anne Marie, Ph.D. "Simple Ways to De-Ice a Windshield." ThoughtCo, Aug. 27, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 27). Simple Ways to De-Ice a Windshield. Retrieved from Helmenstine, Anne Marie, Ph.D. "Simple Ways to De-Ice a Windshield." ThoughtCo. (accessed October 26, 2021).

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