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Fairtax4me's headlight cleaning write-up


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#1 Fairtax4me

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Posted 11 August 2009 - 09:57 PM

A couple people asked for this in my last thread. So here it is, my guide to sanding and polishing your yellowed or faded plastic headlights.

What you'll need...

Headlights :-p
Wet/dry sand paper in varying from about 400 to 2000 grit.
A bottle of plastic polish
A small bucket of water or a spray bottle with water
A buffer with a medium or fine cutting pad, and a high speed polishing pad.
Masking tape.
A hand full of clean, dry, cotton cloths

So your headlights look something like this...
Posted Image
First off, not only does it look bad, but it also cuts the light output of your headlights which can make it hard to see, and even downright dangerous to drive at night. And in several states, lights in this condition will fail safety inspection.
There are several fixes for this. You can replace the headlight assemblies, which can cost hundreds of dollars. You can use toothpaste to clean them up. Or you can use a slightly more permanent solution which is to sand away the oxidation and polish the surface back to a like new shine. Follow this up with an application of a Clear coat safe for use on polycarbonate (plastic), and you get a layer of protection that will last for years without needing any further attention. Most automotive grade clear coats will work for this, but its best to find a knowledgeable supplier in your area to make sure you get the correct type of product. There are some hobby/model grade clear coat sprays that I've used and seem to work well, but how long they last I can't say since the vehicles they were used on were not around for very long afterwards.

I'm mostly going to cover the sanding and polishing in this writeup.

To start, you want to clean the headlights. Bugs, dust, road grime, stuff like that should be removed so that that you don't contaminate your sand paper.

Next mask off the area around the light with masking tape. Any kind of painters tape will work, I used purple because it was the first thing I grabbed out of my shed. You want to mask everything up to about 3 inches away from the edges of the lens. You may want to double up the tape in the areas immediately surrounding the lens.
Posted Image
I have the grille removed here, because the bolts holding the headlight housings in all needed to be tightened.

I started out with 400 grit 3M paper. Dunk the paper into your bucket of water or soak it with a spray bottle and get it good and wet. Spray some water on the surface of the lens and start sanding. Wet sanding keeps the sanding scratches uniform across the surface, it also washes away the dust that comes off when sanding so your paper doesn't get "clogged". You can't really sand with dust. Keeping plenty of water on the lens will make it easier to sand and keep the paper clean. You'll see the water almost immediately start to turn a milky yellowish color.
Posted Image That is the oxidation being removed from the surface. Eventually this will start to turn white.
Posted Image
The white is clean plastic. You want to work your way around the light and continue to sand until you get rid of all of the yellow.
When you've finally made it down to clean plastic wipe the lens off with one of the rags and move on to the next (finer) grit of sand paper.
You'll have something about like this on your lens... These next few pics didn't turn out very well. I couldn't get the camera to focus on the scratches well enough to show a lot of detail.
Posted Image
Your second paper should be in the 800 - 1000 grit range. I used 3M 1000 grit wet/dry. The idea here is to completely remove all of the scratches made by the course paper used before. Same basic procedure, sand around the light until the surface is uniformly covered in the marks of the finer paper. The surface will start to feel smooth under the paper when you start to get through the scratches.
Wipe the lens clean from time to time to check your progress, and see if you've made it all the way through the scratches from the previous paper.
Posted Image
Again once you've made it through switch to the next finer paper. You can make a pass with 1500 grit if you'd like. I jumped right to 2000 to finish off the sanding. Remember to keep the paper and lens wet.
You should end up with a very fine scratch pattern. With no evidence of the previous scratches showing through.
Posted ImageI used the tape to give the camera something to focus on. If you look closely you can see on the left side of the pic where there are some slight marks left over from the previous paper. It started to rain on me so I had to kinda hurry up.
Wipe it dry and put a bead of polish across the front of the lens. I used Meguiars PlastX. There are plenty of other plastic polishes out there. This is a product that I' have a lot of experience with and I know it works well. Its also often less expensive than other polishes and has a few conditioners added to it to help keep the plastic clean for longer after use.
Posted Image
Now time to break out the buffer. I used the cutting pad first on fairly low speed to spread the polish around on the lens. Once the lens is evenly coated you can increase your speed to medium speed. Continuously move across the light from side to side and top to bottom. Don't rest in one place too long or you risk melting the surface of the lens. Buff until the polish has dried away. Switch to your fine polishing pad and repeat the process, only jump up to a higher speed with the buffer. (about 2500 rpm should be plenty. Don't want too much heat here.)
This will be your end result.
Posted Image The surface will be shiny and free of any deep scratch marks. This should only take two passes with a buffer. If the surface comes out hazy looking, use a finer polishing pad. If you can still see scratch marks from the sanding, re-sand using at least 2000 grit paper and re-polish.
Posted Image

Now you can take this whole thing a step further like I mentioned before and spray the lights with a clear coat. There are also some kits out there that have a wipe on sealer included that should work fairly well. If you want to do the clear coat, I'd recommend removing the light assembly from the car. Clean it with wax remover or alcohol. And spray it somewhere that dust wont get all over the lens. Be very careful not to get runs, because they will distort the light output and may cause the beam to reflect somewhere that its not supposed to. (such as into other drivers eyes) Do two to three coats, and allow about 48 hours for the clear to fully cure. You want the surface to be as smooth as possible. If you can see an orange peel like look on the surface, wet sand the lens with 2000 grit paper and polish with a finishing compound. (3M Finesse It works awesome for this).

Edited by Fairtax4me, 11 August 2009 - 10:55 PM.


#2 Fairtax4me

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Posted 11 August 2009 - 09:58 PM

Here are the before/after shots.
Posted Image
Posted Image
Posted Image

Posted Image
Posted Image

Posted Image
Posted Image

Pics of the light output...
There is nothing special about the way these pics were taken. I just set the camera on auto and let it snap the shot. So they are a bit darker than actual, but you can still see a clear difference in light output. I'll try to get some better shots of how it actually looks now a little later.
Low beams before
Posted Image
Low beams after
Posted Image
High beams before
Posted Image
High beams after
Posted Image

All in all, including the time taken to round up all this stuff from the shed and drag it all out to the driveway. This took me about an hour start to finish. I already had everything so my cost = 0. PlastX is about $8 for a bottle at most parts stores. An assortment of 3M sand paper will run you about 5 bucks. Comes with 5 sheets or so ranging from 300 or something like that to about 1500 IIRC. A pack of 2000 grit will be like $3. So for under $20 You get nice clean headlights, you can see (for the most part) at night when you drive, and the best part is they make the car look so much nicer. I'm sure I'll edit this a few times, but for now, Questions?
I'm not the best writer, so if you see something that needs clarification, let me know.

Edited by Fairtax4me, 11 August 2009 - 10:00 PM.


#3 bheinen74

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Posted 11 August 2009 - 10:06 PM

they are making cars safer with airbags and such, but they need to be safer with the composite headlights. half the cars on the road have yellowed lights, and they have night vision problems with good light output.
your before and after at night with the light output is scary.
if the govt forces safety airbags, why dont they force better lasting non yellowing lights?

you definitely improved your safety.

#4 Olnick

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Posted 11 August 2009 - 10:19 PM

Nice job, Fairtax4me. Lookin' good and the nighttime light beam shots are quite impressive. Thanks.

Wonder how many Subie owners will be out with sandpaper, polish, etc. this weekend?

#5 97LGT

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Posted 11 August 2009 - 10:43 PM

i plan on using this write up either sunday(day off) or when i take my month long vacation.

#6 Fairtax4me

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Posted 11 August 2009 - 10:44 PM

they are making cars safer with airbags and such, but they need to be safer with the composite headlights. half the cars on the road have yellowed lights, and they have night vision problems with good light output.
your before and after at night with the light output is scary.
if the govt forces safety airbags, why dont they force better lasting non yellowing lights?

you definitely improved your safety.

The pictures don't do any justice to just how much of a difference there really is. There is a very clear pattern to the beam now that can be seen when I'm driving. Before it was just a bunch of light scattered all around out in front of the car. The lows could still use some improvement though. I have no idea how long these bulbs have been in the car. I'll probably end up buying some Silverstar bulbs for it.

This plastic headlight problem has been around for about two decades now. Only recently have I heard of State governments cracking down on this with safety inspections. I think here in VA they started failing cars for oxidation on the headlights in 2006 or 2007. If it was REALLY bad before it was kind of left to the inspectors discretion. I kinda doubt well ever see any type of legislation concerning plastic headlights though. Even though if you look around you'll see about half the cars on the road today have this problem.

#7 cagranitz

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Posted 12 August 2009 - 11:48 AM

If you have enough foresight to avoid waiting until your lenses get that bad in the first place, you should be able to keep them like new without all of the initial sanding steps by simply buffing the lenses with Plast-X once a year.

Awesome write-up and use of visuals ! :)

#8 Fairtax4me

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Posted 12 August 2009 - 08:38 PM

All you really have to do is put some wax on them whenever you wax the car. It will do the same thing for headlights as it does for the paint, protect them from UV damage, acid rain/hard water, bird droppings, bugs, road grime, all that good stuff.

#9 Rooster2

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Posted 12 August 2009 - 09:11 PM

Nice work! What an improvement. Do you make road trips? My Subie headlights could use some cleaning and polishing!

#10 baccaruda

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Posted 13 August 2009 - 12:23 AM

Thanks for taking the time to write this.

I bought a headlight polishing kit from the auto parts store; it is 1000, 1500, 2000, and 2500 grit sandpaper with some permatex "plastic restoration" polish.

The headlights I'm working on ('01 OBW) have a lot of very small chips in them as well as being yellowed, from a lot of highway miles. I was thinking to either get some coarser grit like 800 for them, or get a polishing wheel for my Dremel tool and be very careful. I think I'd rather use 400g instead of the Dremel, though. I wasn't sure about how coarse was too coarse.

Anyway, the instructions in my "kit" say to sand one direction at a time, up/down or left/right and not to sand in circles. I wanted your opinion on this as I didn't see it addressed in your write-up... cheers!

#11 96-LEGACY-L

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Posted 13 August 2009 - 12:52 AM

i was one of the peeps to request a write-up. this is exactly what i was lookin for. i know what im doing this week end.:grin: those are the improvements i need on my wagon. great write up

#12 Fairtax4me

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Posted 13 August 2009 - 12:15 PM

Anyway, the instructions in my "kit" say to sand one direction at a time, up/down or left/right and not to sand in circles. I wanted your opinion on this as I didn't see it addressed in your write-up... cheers!

Doesn't really matter as long as you sand completely through the marks left by the previous paper. At the end the marks will be so fine that they will polish right out.
I wouldn't go any lower than 300 grit. I would have probably started mine with 500, except I didn't have any. 400 was the next closest thing I had. Usually the grains used on course paper are less uniform. Meaning that the grains may be drastically different sizes. That's going to leave some scratches deeper than others, which makes it more difficult to sand through them. You may think it will save some time to use a courser paper at the start, but in the end it will just take longer to remove the scratches left by the course paper.

It is very easy to go wrong with a dremel. Some of the chips you may just have to leave. Trying to cut them out with a grinding or sanding wheel you run the risk of making the hole deeper, and that will be even harder to sand through, and it could end up looking worse than just leaving the chip there.

Edited by Fairtax4me, 13 August 2009 - 12:18 PM.


#13 OB99W

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Posted 13 August 2009 - 05:05 PM

[...]You can use toothpaste to clean them up.[...]

If the lenses are too far gone for toothpaste but not so bad that sanding is required, automotive rubbing and polishing compound might be an alternative. See http://automotive.ha...g-compound.aspx . A protective coat (wax or more) would still be a good idea after such polishing.




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