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DIY Headlight Restoration Hints and Tips

How to avoid DIY headlight restoration disasters

School of YouTube

YouTube is full of "helpful" videos of various inexpensive DIY techniques to improve your cloudy headlights. As a professional headlight restorer I have come across many of them. Some are more effective than others. Some are just nasty. We all like saving some money so if you want to have-a-go yourself by all means do so, but I have listed below some things from my experience that you need to consider before doing any of these to your car, especially as some can do irreparable damage.

Firstly a quick explainer on why your headlights are cloudy:

Before we talk about the fixes let's understand the cause of the problem. Headlights go cloudy mainly due to Ultra Violet (UV) damage from the harsh NZ sun light. The plastic (ie. polycarbonate) used in headlights naturally goes cloudy very quickly due to oxidisation on the surface. To stop this car manufacturers coat the headlight lens with a clear coat coating. This however breaks down over time (several years) and will itself become hazy and cloudy, and sometimes starts yellowing as it degrades. 

So the cloudiness you see on your headlights is the result multiple processes: 

  1. The degradation of the protective clear coat layer
  2. Oxidation of the exposed polycarbonate surface now that the clear coat layer has failed, and...
  3. The 'roughing up' of the headlight surface due to ballistic particles, dust and stones that strike the surface as the vehicle speeds along. 
The affect of this is a considerable reduction in the performance of the headlights: a significant drop in amount of light output due to the filtering affect of the opaque 'cloudiness' on the lens surface, and a decrease in the quality of the light output caused by light scatter, de-focusing the beam from where it should be directed - on the road ahead. (Fyi. this scattering causes the halo affect you see when a car with cloudy headlights drives towards you at night).

And of course cloudy headlights make you car look terrible.

OK, so now armed with knowledge of the causes of cloudy headlights let's explore the options available to fix them, and helpful advice to avoid any DIY headlight restoration disasters. 

Toothpaste

Believe it or not toothpaste may produce some small aesthetic (albeit temporary) improvement, but will do little to restore headlight performance or light output quality.

Toothpaste contains a light abrasive which when rubbed on the lens can remove some of the exposed oxidised layer from lightly clouded headlights, but it will have little affect on more heavily clouded surfaces, and will fail to remove much of the remaining clear coat resulting in a patchy finish. Also any improvement will be very temporary as without a UV resistant sealant to protect the lens the headlight will instantly start clouding again and will soon be back to where it was before.

That said, there is little chance of doing any lasting damage so if you want to try something yourself give toothpaste a go. There are plenty of how-to videos on YouTube

Sandpaper

Sandpaper is much more abrasive and therefore more effective at removing oxidation and old clear coat. However you need to be very very careful as it is exceedingly easy to damage the lens surface leaving deep scratches. This is probably the most common DIY headlight restoration disaster that we are asked to try and put right. 

You need to make sure you use the correct grades of sandpaper. Assuming you are doing it by hand don't use anything less than 800 grit paper. Also better to use a sanding block to avoid applying too much pressure on one area and leaving deep scratches. Once you have removed the oxidation and old clear coat you need to go over the entire surface again with a less abrasive sandpaper to remove the 800 grit sanding marks. Then keep repeating with finer and finer sandpaper until you get to 2000 to 3000 grit. 

Once finished the polycarbonate will be fully exposed so you will now need to apply a sealant layer to stop the oxidation process undoing all your hard work. See below.

Please note: It is difficult to carryout this procedure without leaving scratches. We recommend only trying it if you are confident in your ability and your sanding technique.

Waxes and Polish

Once the oxidation and old perished clear coat is removed and the surface prepared you will note that the surface immediately starts clouding again. This is due to oxidation. To stop this you need to apply a sealant layer. Many DIY restoration techniques use polishes and waxes to achieve this. The advantages of these are that they are quick and easy to apply and require no specialist skill or equipment. The downside is that they are only temporary. Like wax applied to your car bodywork the full affect will only last for weeks or months. You will have to keep re-applying it regularly if you want to stop your headlight's performance dropping again.

Clear Coat Aerosol Sprays and Wipes

The best sealant is a layer of clear coat, just as the headlight originally had, and the best way to apply it is with air powered professional spray equipment. But of course not many DIYers have this sort of equipment to hand. There are however more accessible alternatives, but as always they involve compromises. 

Wipe-on clear coat solutions have been developed which have the big advantage of being quick and easy to apply, however the coating they leave on the headlight will be very thin due to the method of application. In my experience it doesn't result in much protection and the improvements to the headlights was frustratingly short lived. 

Clear coat aerosol spray cans are another option. Of course if you use these you will first need to mask the front of the vehicle. Use masking tape around the edges of the headlights and large plastic sheets to cover and protect the surrounding bodywork from over spray. 

I would recommend using a 2K (2 part) clear coat aerosol as this cures to a harder and therefore more durable finish.

You should practice on a smooth flat surface before attempting your lights as getting a good finish from an aerosol can is harder than it looks often resulting in a rough 'orange peel' finish.

Headlight Restoration Kits

There are many many of these kits available, and all will claim to restore your headlights back to clear. They range in price from around $40 to $80+. They should all contain some sort of abrasives for removing the cloud and a sealant finish to keep them clear. They vary in the exact technique and methods they use to achieve the end result so use the information above to determine for yourself which should be most effective. Be sceptical about any bold or hard to believe claims, especially around the process being effortless or quick as it should involve a fair amount of time and elbow grease to get the best results.

As with the individual steps outlined above the common pitfalls with these DIY restoration kits, that we are called on to put right, are sanding scratches left on the lens and poor finish of the sealant layer. 

Professional Headlight Restoration Service

Of course if you want the best result without the risk and effort, our recommendation would be to use the services of a professional headlight restorer. We do this day in day out. We are headlight restoration experts.

Full Beam Headlight Restoration are the cloudy headlight fixers

We are a mobile service covering most of Auckland.

Our promise is to restore you headlights back to crystal clear or your money back*

For prices, availability and more information