How do I de-ice a car properly and safely?

Everyone is in a hurry when the car is frozen, which is why this is where people crack windscreens, scratch glass and set off half-blind. The efficient order is not the intuitive one.

Safety

Step by step

1. Start the engine and set the blowers first.Full heat, directed at the windscreen, air conditioning on if you have it — it dries the air and clears the inside far faster. Rear screen heater on. Then get out and scrape while it works.
2. Do not sit inside waiting.The demister takes several minutes to make a difference. Scraping the outside during that time means both jobs finish together instead of one after the other.
3. Use de-icer spray on the thickest ice.Spray and give it thirty seconds to work before scraping. It softens the bond to the glass so the scraper lifts sheets rather than shaving at it.
4. Scrape with a proper plastic scraper.Held flat, pushed in long strokes. Not a credit card, not a CD case, and never anything metal — all of them scratch glass, and scratches scatter light straight into your eyes at night.
5. Never use hot or boiling water.The temperature difference across cold glass causes it to crack, and an existing chip will spread instantly. Lukewarm water is safer but refreezes on the glass and on the ground where you will then walk.
6. Clear every window, not just a patch.Windscreen, both front windows, rear screen, rear side windows. Driving with a cleared letterbox is an offence and it removes exactly the peripheral vision you need on an icy road.
7. Do the mirrors and all the lights.Both wing mirrors, headlights, tail lights, indicators and the number plate. Frosted-over rear lights are invisible to the car behind on a dark morning.
8. Clear the roof as well.Snow on the roof slides forward onto the windscreen at the first firm brake, or off the back into the car behind. It takes thirty seconds and it is the step most often skipped.
9. Check the wipers are free before switching them on.Wipers frozen to the glass will strip the blade rubber or burn out the motor. Lift them gently to confirm they move first.
10. Do not leave the car running unattended.An idling car with the keys in is a theft that most insurers will not cover, and idling unnecessarily on a public road is an offence. Stay with it.
11. Prepare the night before if you can.A windscreen cover, wipers lifted off the glass, and a car parked facing east so the morning sun helps. Two minutes at night removes most of the problem in the morning.
12. Deal with frozen doors and locks properly.Push the door firmly inwards first to break the seal rather than yanking the handle, which tears the rubber. For a frozen lock, warm the key or use a lock de-icer — never force it.

Tips

• Screenwash concentrate mixed for winter matters as much as de-icer. Summer-strength washer fluid freezes in the reservoir and in the jets when you most need it.
• A windscreen cover, or even a cut-open cardboard box under the wipers, removes the scraping entirely.
• Keep the de-icer and scraper in the house, not the car. A can of de-icer frozen inside a locked frozen car helps nobody.

Common mistakes

• Pouring hot water on the windscreen — Thermal shock cracks glass, and any existing chip spreads immediately. A windscreen costs vastly more than the minutes it saves.
• Clearing only a patch in front of the driver — It is an offence, it invalidates insurance in a collision, and it removes the peripheral vision that matters most on a slippery road.

If it doesn't work

Questions people ask