How to defrost a frozen windscreen

The Safest Way to Defrost a Windscreen

The Nordic wind is sweeping over the country again and we’re finding a frost gathering on the car windscreen. First thing in the morning, you’re in a hurry and need to know the safest way to defrost a windscreen. Here’s the VFR Motors thoughts on the topic.

Your usual windscreen defrosting options go along the lines of:

  • Hot Water
  • The Latest TikTok Fad
  • De-icer
  • Patience and The Car’s Own Demisting Fans
  • Windscreen Scraper

Hot Water

So this seems like a great way to defrost a windscreen. It’s quick. It’s easy. All you need to do is boil the kettle and chuck on the windscreen and tah-dah! Ice gone.

But, think about the conditions. Your car has been sitting out in the cold all night. So you windscreen could be between -2 and -10 degrees centigrade. Very flipping cold in other words!

In contrast, the hot water from the kettle could be around 80 to 100 degrees depending on how long you leave it to cool. This difference puts a sudden expansion shock on the laminated glass of your windscreen.

Such a sudden difference of temperature can easily cause the windscreen to crack. Depending on the location of the crack, this could mean an expensive repair, and possibly MOT failure.

The short story: never ever ever ever use boiling water or very hot water to defrost your windscreen.

The Latest TikTok Fad

Similar to the kettle of hot water is the hot-water-in-a-bag method as touted on TikTok. True, this does limit the shock factor because there’s not as much contact with the screen and the temperature difference is not so great.

We’re still not in favour of anything that involves a big temperature shock to the glass. However, if you do want to use this method, there are some extra steps you should add in:

  • Make sure the wipers aren’t frozen to the windscreen
  • Start the car
  • Put the heater on
  • Turn the fans on full and make sure the setting is on demist
  • Switch the wipers on if they’re not frozen to the windscreen
  • Apply the TikTok idea (if you insist!)
  • Immediately use the wipers to remove any excess water or moisture from the screen

This last step is particularly important. If you don’t remove the excess water from your windscreen, you run the risk of having the water re-freeze. Leaving you right back where you started.


This is a quick and easy solution. It’s effective and doesn’t refreeze like water. But, most de-icers come in an aerosol dispenser which is bad for environment. So if you want to use de-icer, look out for a pump action dispenser.

What’s more, de-icer is chemical based which is not great for the environment either. Plus the ingredients of de-icer can have an adverse effect on the wiper blades, making them harden over time.

Patience and The Car’s Own Demisting Fans

This is the old-fashioned approach and is low impact in terms of the potential damage to the car and it does defrost your windscreen.

The problem here is it’s now illegal to sit in your car with the engine running or leave it unattended with the engine running. It’s not great for the environment because while your car is running it’s kicking out all those nasty emissions.

Good Old Fashioned Windscreen Scraper

Now this is harder work but is by far the best way to limit damage to your vehicle if you need to defrost a frozen windscreen.

The pros are:

  • Removes ALL the moisture and ice from the windscreen
  • Best for the environment as it can be reused multiple times
  • Good for your health as it gives you a mini morning workout!

The downside is that it does require some elbow grease and there is a small risk of scratching the windscreen. For this reason, we suggest:

  • Invest in a quality scraper. Get a good one and it will last for years.
  • Look after your scraper! Don’t leave it on the floor where it can pick up bits of grit and get damage.
  • Make sure it’s clean before you use it. Run your fingers or a clean cloth along the scraping blade first.

Last Bits

According to the Highway Code, motorists must make sure their windscreen is clear before they drive. So it’s important to fully clear your windscreen of frost and ice before you drive. Limited visibility is dangerous for you and other road users, so thoroughly defrost your windscreen before you set off. Driving with a frosty or snow-covered windscreen could get you stopped by the police.

If you have a cracked windscreen we can help but this will normally involve your insurance company and their preferred third party windscreen replacement supplier.

Please give us a call on 0116 3190 118 or mobile 07850 881 911get in touch via our contact form, or drop in for a chat at our friendly garage at on Shaftsbury Road, Leicester, LE3 0QN.

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