Product reviews3M 39173 Quick Headlight Clear Coat Improve and Extend Clarity of Lenses

4.84.8 out of 5 stars

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12 reviews

by martin1208j29 Dec, 2020Most favourable review

Pleasantly surprised - does exactly what it claims

There are many 'how to' videos on YouTube and, being sceptical, I found it worthwhile to watch a few of them before buying this product. These videos also gave me the confidence to 'scrub' the plastic side-light lenses on my car with abrasive wet & dry paper in the knowledge that the end result could be much better. And, it proved to be so.

The lenses fit into the front bumper and are low down and close to the ground. The plastic lenses were originally coated by the manufacturer. As you can see in the first 2 pictures, a lot of the coating has been scrubbed off over the years and, there was some minor pitting/stone chips and a few scratches.

One of the videos, showed a professional restorer initially check the lights for pits, chips and scratches. He used a safety razor blade to remove/smooth out any 'lumpy bits'. I did the same using a diy craft knife with a new blade.

The abrasive disc supplied in the pack is a 'finishing' grade at 3000 grit. And, I doubted that the coating on my lenses would be easily removed using so fine a grade of grit. The videos provided useful information on the grades of grit to use. I purchased some wet & dry abrasive paper from an eBay seller offering 'select you own grades' pack of 5 sheets. I chose 600, 800, 1200, 2000 & 2500. But, only used 2 of them...

The 2 coarser grades were tested on corners of the lenses and were a little too coarse, even using water to lubricate the cutting action. So, I moved on to the 1200 grade grit and this worked really well using long strokes back & forth (rather than a swirling rotary motion) in line with the length of these narrow lenses. As expected, the lenses came up cloudy but smooth and all of the coating had been removed.

The 2000 grade grit was then used 'across' the lens - at 90 degrees to the direction of the 1200 grade, until the surface was as smooth as reasonably possible. (Some pits couldn't be removed - these lenses had travelled over 102,000 miles). The cloudiness had reduced quite a bit by now and the lenses were becoming translucent.

The supplied 3M Trizact disc (3000 grade) was then used in the same back & forth direction as the 1200 grade. After a while, the cloudiness had further reduced. So, I now used the same disc 'across' the lenses under running water from the kitchen sink tap and the cloudiness had almost gone. In fact, the lenses were now much better than when I started - seriously, see the 3rd picture!

Next, I made sure that the whole of each light fitting was clean and thoroughly dry (kitchen paper is great). The end of a coating sachet was then cut off and the cloth removed. Again, one of the videos had mentioned that some of the coating had 'run' when applied to a vertically disposed light lens. So, keeping my fingers off the lenses and holding the black body of the light so that the lens was roughly horizontal, I wiped the cloth in 2 long strokes over each lens. And, subsequently re-coated each lens with the same cloth several times at 30 minute intervals (replacing the still wet cloth in the sachet each time) keeping the lenses horizontal all the time - no drips, no runs - see the 4th photo for the result after they had been left over night - impressive, I think. And, with the lights re-fitted – see 5th photo.

These lenses were easily removed from the car so there was no need for the masking off of adjacent paintwork nor ending up with a gooey mess on the garage floor. The bulbs and their holders were left in the lights to stop water getting inside and causing fogging. The lenses were abraded in the kitchen sink which obviously had a ready supply of warm water and made the abrading and cleaning much easier. But, I think the time of 20-30 minutes claimed in the videos to do this job is understated. Obviously, it will depend on the condition of the lenses. I spent around two and a half hours in total. And, I think it was time well spent on a wet Sunday afternoon. To replace these lights would have cost around £650. It actually cost me less than £15 in materials.
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