Fiat Siena: DIY Headlamp Outer Glass Restoration (plastic type)

In this yet another series on my 1999 Fiat Siena restoration, I’m sharing my experiences on periodic cleaning and restoration of the 23-year old car’s aftermarket-made, plastic-type headlamps that are serving in my car for about 10 years now.

As you can see in the video, the headlamps became dull with slight yellowish tone, and there were rough scalp-like formation in the outer lens, which was actually the oxidized clear coat that have started to come off over the time. Lately in the last few years, the deterioration of the headlamp’s outer glass was becoming more prominent, which warranted effective cleaning and maintenance. 

However, I’m quite surprised that these aftermarket headlamps have lasted this far, and I hope I can take partial credit for my care and maintenance approach. I always ensure that I don’t park the car in direct sunlight for longer periods. At home, I usually wrap the car with body cover to prevent sun rays. I also do some periodic cleaning to keep the headlamps healthy.

I don’t claim that I do some innovative or magical restoration work, but I’m just gonna show my way of doing periodic maintenance to my car’s headlamps. Simple, easy and practical methods that does show some good results. If there are any better methods, do share it in the comments section.

The process

The first thing I did was to blow away the dust from the headlamp assembly. We don’t necessarily have to remove the assemblies from the car for the cleaning. I then used a 1000 number, fine grit emery sheet or sandpaper to scrape the outer lens carefully. I ensured that I did not leave any scratch marks in this process.

I then added some diluted liquid soap water to the outer lens, to wet the emery sheet. Alternatively, I also used a toothbrush to ward off the rough, particle-like dust. Once done, I then washed away the soap and dried the headlamps with a cloth.

In the next step, I applied a standard tooth paste over the headlamp and rub using a toothbrush. The silica and hydrogen peroxide in the tooth paste is said to bleach the oxidized plastic or outer glass in headlamps, in a similar way it does on out teeth. Gel type tooth pastes won’t work, we need some grittiness for abrasive rubbing. If it felt too dry to rub, I sprayed some water to make it little better.

I usually rub for some 15 mins and pay more attention to those spots that are rough and not smooth. At times, I also repeat the process all over again to get better results. I then blow dried the assembly completely using a blower to ensure water droplets are not present anywhere in the assembly, both inside and out.

The result was largely satisfying. The headlamp outer glass was relatively smooth and clear after the cleaning process. I even suggest the process with those headlamps assemblies with clear, reflector-optic out glasses as well. I can assure you that the results we get are certainly worth the simply and easy efforts we put in.

Also Read: Fiat Siena: Cleaning rusty fuel tank | DIY Car Restoration

Do share you experiences and suggestions in the comments sections. Subscribe to our channel WagenClub + for more restoration related videos.

Dhiyanesh Ravichandran

Editorial consultant (Automotive and Technology), academic, and blogger based in India. He can be reached at

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