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Viral video offers clear way to defog car windows faster

  • Author: Alaska News
  • Updated: September 28, 2016
  • Published January 12, 2016

As Anchorage and the Mat-Su deal with a wave of freezing rain Tuesday morning, a former NASA employee's YouTube video explaining a faster way to remove fog from car windows is going viral.

Mark Rober's Jan. 5 clip, "Defog your windows TWICE as fast using SCIENCE," had nearly 2 million views Tuesday morning. Here's a look at the video, which offers a method to clear the inside surface of vehicle windows more quickly based on a scientific understanding of humidity:

The key steps, Rober says, begin with turning up the heat in the car, "increasing the size of your towel" to soak up moisture by expanding the air's capacity to absorb it. Once that's done, he says, it's important to activate the air conditioning, because air passing over the cold coils of the AC system draws out more moisture, as well as the vehicle's external air circulation to draw in some low-humidity winter air.

Last but not least, Rober recommends slightly opening the car windows for a few seconds to let some of the interior air escape -- although that depends on weather.

"This may not be possible if it's freezing cold or it's raining outside," Rober said. "But cracking as many windows as possible, even for a few seconds, helps by exchanging the humid air from your car with the dry air outside."

Within the vehicle, Rober says a sock filled with cat litter left on the dashboard can absorb moisture and reduce fog on the inside of the windshield. Special anti-fog liquids, sold in automotive stores and rubbed onto the glass, can also help -- although Rober says shaving cream costs less and works just as well.

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