This viral internet life hack claims that leaving an open glass or bowl of salt in your car will solve common cold-weather nuisances.
Here is why some drivers try this trick, what it is supposed to do, and why mechanics generally suggest skipping it.
What the Trick Claims to Do
The theory behind the “glass of salt” hack relies on a basic scientific property: salt is hygroscopic, meaning it naturally attracts and absorbs moisture from the surrounding air.
Proponents suggest that placing a dish of salt in your car will:
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Act as a natural dehumidifier to pull humidity out of the cabin.
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Prevent foggy windows and stubborn interior condensation on cold mornings.
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Reduce musty odors caused by trapped moisture.
Why It Doesn’t Work Very Well in Practice
While the chemistry is real, using a simple glass of table salt in a moving vehicle has major limitations:
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It’s Extremely Slow: Table salt only begins absorbing moisture effectively when relative humidity is very high (usually around 75% or higher). It cannot pull enough water out of the air quickly enough to stop a car windshield from fogging up when you breathe inside a cold vehicle.
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The Spill Hazard: Leaving an open glass or bowl of loose salt on your dashboard, center console, or seat is an invitation for a messy spill. A sharp turn or a sudden stop will send salt all over your upholstery or electronics.
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Rust Risks: If the salt successfully absorbs a lot of moisture, it liquefies into salty brine. Spilling liquid saltwater inside your car cabin can accelerate corrosion on metal components, seat frames, or electronics hidden under the carpet.
Better Ways to Handle Moisture and Foggy Windows
If you are dealing with chronic moisture, foggy windows, or musty smells in your car, these methods are far more effective than a glass of salt:
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Use Your A/C: Turning on your air conditioner (even when running the heater) actively pulls moisture out of the air because the A/C compressor acts as a powerful dehumidifier.
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Check for Leaks: If your windows fog up constantly, it usually means water is physically getting inside your car. Check for clogged sunroof drains, a blocked A/C drain tube, or damp floor mats after heavy rain.
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Change Your Cabin Air Filter: A clogged or dirty cabin air filter restricts airflow and traps humidity inside the vehicle.
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Commercial Desiccants: If you want passive moisture absorption, use a sealed, spill-proof moisture absorber pouch (like those filled with silica gel or calcium chloride) designed specifically for vehicles or closets.
