Headlight restoration guide — when and how to replace or restore them

Foggy headlights and dimming beams affect even the most conscientious drivers, so let’s look at why your lights might not be as bright as they once were, and the different ways you can restore them.

How headlights degrade

There are two main ways that your headlights degrade over time:

  • Dimming bulbs
  • Discoloured headlight casing

It’s important to work out what part of your headlight has degraded before attempting to repair them.

Headlight bulb lifespan

Headlight bulbs will dim over time through wear and tear. The range of bulbs used in headlights typically last for:

  • Halogen: 500 — 1,000 hours
  • LED: 30,000 hours
  • Xenon: 10,000 hours

Headlight casing becoming cloudy

Headlight casing can become cloudy or appear yellow for several reasons:

  • Oxidisation: headlight lenses are coated in a clear layer to help prevent acrylic from oxidising. Over time the coating wears off and UV light oxidises the casing, turning it yellow.
  • Wear and tear: your protective coating is prone to scrapes and scratches from debris on the road, when this reaches beyond the protective layer the casing becomes damaged and appears cloudy.
  • Dirt: after miles on the road, a thin layer of dirt and chemicals from pollution can gather on headlight casing, dimming your beams.
  • Water vapour: headlights come with a watertight seal that often breaks through wear and tear, once this happens water can collect inside the casing, scattering beams of light.

Even with bulbs in perfect condition, your headlights will appear dim or discoloured when you have cloudy/foggy casing.

When to replace or restore headlights

The highway code (Rule 226) says: “You must use headlights when visibility is seriously reduced”, with ‘seriously reduced’ defined as when you are able to see less than 100 metres in front of you.

As headlights must be used during the hours of darkness (Rule 113), where ‘hours of darkness’ is defined as the period between half an hour after sunset and half an hour before sunrise, it’s important that your headlights are bright enough to see 100 metres in front of you at all times.

Use these distances to decide if you should replace or restore your bulbs. Make sure you replace both sides at the same time for even illumination.

Watch this video for tips on how best to check your car’s lights.

Restoring headlights

There are three approaches you could take when restoring your headlights. The unconventional DIY route, the more traditional DIY route, or simply leaving it to the experts. Here’s each option, step by step.

Using household items to restore headlights

Before restoring your headlights it’s important to start with a clean surface. Use a car shampoo to begin and then pick your weapon of choice.

Toothpaste

Thanks to the abrasive elements of gritty toothpaste, it can gently wear away a surface layer of scrapes and scratches on your headlight casing.

  1. Apply toothpaste with baking soda (the gritty kind) to your headlight lenses, using a toothbrush
  2. Apply until you see the toothpaste turn dirty, or start to discolour
  3. Leave to dry
  4. Gently wash it off with a cloth and warm water

Sandpaper

  1. Tape off your paintwork to prevent any accidental damage
  2. Wet your headlight
  3. Wet 400 grit sandpaper and smooth across the surface of the headlight while avoiding motions that dig into the casing
  4. Sand any especially gritty areas on the casing and regularly check your work
  5. Repeat with a 600 grit sandpaper and, if needed 1000 and 2000 grit sandpaper – you may need to apply extra pressure with 2000 grit
  6. Wipe with a towel to finish

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