How to Wet Sand Foggy Plastic Headlights [8 Steps]

After doing some research, I decided to try to restore my truck’s plastic headlights today. After trying nearly ever DIY technique out there in an attempt to clear up foggy headlights, none of them worked for me. The toothpaste trick, even compounding and polishing — but still that foggy haze remained.

If you have reached the point where nothing seems to be working like I had, it may be time for wet sanding.

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In this blog post, I’ll break down my experience with the technique, what products you need to use in order make this effective, and how to protect your headlights one finished. Keep in mind that this is a DIY solution, and individual results may vary. I just thought I’d share what worked for me.

What You Will Need

Contrary to what I originally thought, this process was a a lot messier and time consuming than I originally expected. I’d say budget somewhere around 30 to 45 minutes per headlight to achieve the results you want, but it depends on how cloudy your headlights are.

Here is a list of materials you will need to get started:

  • Painters tape
  • Trash bags or plastic
  • +61404532026 grit sandpaper (600, 1000 and 2500 is common) but numerous grits from +61404532026 depending on the cloudiness
  • Spray bottle with water
  • Car soap (or Dawn)
  • Isopropyl (rubbing) alcohol
  • Polishing compound
  • Polish
  • Multiple microfiber towels
  • Foam buffing pads
  • Drill with polisher attachment (or polisher)
  • Face mask and glasses
  • Rubber gloves

Step 1: Tape off the headlights and cover the paint

Before you get started, it’s a good idea to tape off your headlights with painters tape since you will be using sandpaper. This will make it quicker to work since you won’t have to worry about making contact with the paint. I was careful around the edges, but will definitely do this in the future.

I would also cut a hole in a piece of plastic (like a trash bag) that is the same size as the headlight before taping around the headlight itself. This is totally up to you, but unless you plan on washing your vehicle after the headlight restoration process, you will likely be dealing with dust (or dried dust) from wet sanding.

Step 2: Start with dry sanding

I’d recommend wearing gloves and possibly a face mask and glasses for this step, since dust tends to fly around a lot when dry sanding. Wet sanding didn’t give me any problems, but the dust tends to get everywhere.

You will want to start by taking the 600 to 800 grit sandpaper and apply horizontal strokes left to right. They make handheld palm sanders you can use (with circular sanding sheets) that make it easier to apply more pressure which I’d recommend.

I just found a pack of rectangular sandpaper sheets in numerous grits on Amazon, but they make them for palm sanders also.

Keep in mind, an orbital sander (or DA polisher) with sandpaper disks can work as well, just be sure that you are comfortable using them since you don’t want to apply too much heat to plastic.

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For beginners, sandpaper (or a sample handheld sanding block) usually works pretty well unless you have an extreme case where a power tool will save you some time.

What is this white dust anyway?

Simply put, this is a UV coating applied by the manufacturer to help protect your headlights from fading or turning yellow over time. The problem is that the sun will actually burn up this coating as the car gets older, causing your headlights to appear foggy.

You’re essentially removing this coating (which can be quite labor intensive) using dry sanding to expose the clear plastic underneath. Dry sanding is best for removing substances, while wet sanding is really for polishing. Water acts as a lubricant needed to polish out the scratches dry sanding produced.

Step 3 – Wet sanding with +61404532026 grit sandpaper

This is where it gets fun. Take your water bottle (a bucket of soap and water works great too) and rinse off the initial white powder. The purpose of dry sanding is to take off the rough, caked on substances. If you started with 600, wet sand with 800. If you started with 800, wet sand with 1,000 grit, (and so on).

In between these various phases I sprayed down the surface with soap and water to remove this milky white liquid. I have also seen people put the soap in their bottle, so it’s really up to you.

Dawn dish soap is actually pretty good for de-greasing if you have it, although you may not want to wash your vehicle with it. Washing with dish liquid I don’t recommend, but it does have it’s place in detailing as I wrote about here.

Tip: Sand in the opposite direction for each phase

This is a crosshatching technique that can help remove scratches as you work. Sanding on plastic removes big scratches while creating smaller ones, so by working in opposite directions for each grit of sandpaper, the goal is to eventually get to the point where there are no visible scratches, and you have a clear surface.

Step 4 – Apply polishing compound

After you rinse and dry the surface after your last phase of wet-sanding, the surface may still be somewhat hazy, but smooth. I would recommend a dual-action polisher or rotary buffer (more powerful) when applying compound.

Apply a decent amount to a clean pad, and evenly apply it to the headlight lens.

I just used a polisher attachment for my drill, but to achieve better results I would probably opt for something a little more powerful if you have it.

Once you have applied compound, the next step is to polish.

Step 5 – Apply polish

The next step is to wipe down the compounded surface with a microfiber towel and apply a polish. Polish is less abrasive than polishing compound and will further smooth out any micro-scratches caused by compounding. Simply apply some to a clean pad and wipe down when finished.

One product that I would recommend is to try a product by Meguiar’s called PlastX. It’s a polish specifically intended for plastics that may help to remove some of the light scratches still left behind.

If you’re a little confused as to the difference between polishes, compounds, or waxes (and what they do), check out our post: Compound vs Clay, Polish & Glaze! 7 Products to Understand.

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Step 6 – Apply isopropyl alcohol

After you have removed the polish and buffed the surface, everything should look pretty clear. This is where I would apply isopropyl alcohol (or an IPA wipedown solution) with a microfiber towel. this will simply remove any contaminants still left behind (like compound or polish) and leave you with a glassy smooth surface.

Isopropyl alcohol, when used properly has a few different uses in detailing as I recently discussed in this post.

Step 7 – Evaluate & repeat if necessary

At this point, simply re-evaluate your work until you achieve the results you’re looking for. You may need to repeat a few steps in the process if you still can see some scratches, but I would probably revert back to polishing compound (or rubbing compound) to help remove some of these light scratches. From there, simply follow the same steps.

Sometimes the headlight lens may be damaged from the inside due to moisture or cracking, in which case there isn’t much you can do outside of replacing the headlight lens itself.

Step 8 – Apply UV protective coating

Only after you are satisfied with the clarity of your headlights should you proceed to applying UV protective coating. This will help maintain clarity for a lot longer than if you do not apply a UV coating.

Meguiars makes a headlight coating specifically for this purpose that I use, but you can find a variety of UV coatings from manufacturers like Sylvania or Spraymax. Any solution that contains a UV protectant should be fine, even if you opt for a clear sealant or coating.

I would apply this coating as evenly as possible in light coats, as I have had beads of it dry on contact by mistake. It’s always best to apply several light coats than a heavy one, especially since you will already have everything taped off.

What to keep in mind with wetsanding

The purpose of wetsanding is simply to polish away light scratches. The dry sanding really is what should remove the actual UV coating itself. For that reason, I wouldn’t really go too overboard with the sandpaper alone (using too much grit), because sandpaper alone will create scratches that were not already on your headlight once the UV layer is gone.

Removing layers of smaller scratches not originally on the headlight was a little more difficult than I imagined, and I probably should have been a little more gentle with step 2 looking back.

Nevertheless, you should be able to get your headlights pretty close to clear after compounding and polishing.

Conclusion

All in all, this process should at least improve the clarity of your headlights when done properly. However, in some circumstances where the plastic is just old, there may not be much you can do. As you can tell in the picture below, I did see a drastic improvement in clarity after wetsanding as opposed to compounding and other DIY techniques I’ve tried.

I hope this post has been helpful if you are considering tackling wetsanding. Let me know in the comments any additional tips to be aware of that worked for you.

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