Strav's blog

I've done a fair amount of research into restoring headlights over the past few years and never ended up doing the restoration since the information I found was incomplete, contradictory, or just plain wrong.  Recently I found a post (link and complete text below) that completely explains the issue as well as supplying the recommended solution.  For the sake of brevity, I'll extract the most relevant information, but the entire post from ray6 is worth a read.

Problem: Yellowing or hazing of headlights

Reason: Polycarbonate (trade name Lexan) is the material used on headlights starting in 1989.  Polycarbonate is susceptible to UV rays (sunlight) and will break down with direct exposure so the headlights are treated with a protective coating.  The discoloration is the coating breaking down over time (i.e. doing it's job).

Solution: Remove the failed coating (I will detail the steps I used for this below) and apply a new protective coating.  Unfortunately, it is not cost effective to reapply the manufacturers coating so the current recommendation (also by ray6) is Delta Kits Infinity 4.1 coating.  Here is a link to a youtube video with a nice example of the restoration process, though they use different materials. If the UV coating is not applied, your headlights will rapidly return to their damaged state and the restoration process will be much more difficult as you will have to remove the much more durable polycarbonate material rather than a coating.

Materials required for restoration:

1. Wet/Dry sandpaper (400,1000,2000/2500,3000/3500)
2. Rubbing Compound
3. Polishing Compound
4. Flexible Sanding Block
5. Infinity 4.1 Coating
6. Microfiber Towels
7. Spray Bottle
8. Foam Paint Brush

Restoration procedure:

1. Remove headlight or tape off the area of the car surrounding the headlight
2. IMPORTANT: whenever doing any sanding, the headlight and sandpaper should be wet.  You can dip the paper in water or use a spray bottle filled with water directly on the headlight.  Also, it's best to sand in a single direction (side to side) rather than random or in circles.
3. Use the 400 grit sandpaper gently to remove the bulk of the failed coating.  Being too agressive with the 400 will result in deep scratches that will require a lot more work with the other sandpaper to work out
4. Use the 1000 grit sandpaper to remove any remaining coating and begin to remove the scratches left by the 400 grit sandpaper.  At the end of this step, the surface should be very smooth, though still quite hazy.
5. Use the 2000 grit sandpaper to continue the polishing process. As you use this, the haze will begin to fade some, though it will not be clear until the rubbing/polishing process.
6. Use the 3000 grit sandpaper as the final sanding stage.  The more work you do here, the easier the rubbing/polishing process will be.
7. Use the rubbing compound to really start to make the lens clear again.  Apply a small amount to a towel (I used microfiber) and rub it in until it disappears.  By the end of this step, the scratches should be gone from the lens, though it won't be crystal clear.
8. Use the polishing compound to finalize the restoration process.  At the end of this step, the headlight should essentially look brand new.  If there are any scratches left, reapply rubbing compound then polishing to those areas.
9. Make sure the headlight is clean and free of any foreign material then apply the Infinity Coating (mix according to instructions) using the foam paint brush.  Apply by first using horizontal strokes then cross wiping vertically.  Do this very quickly as the coating cures rapidly.  It will go on milky white and streaky - try to minimize the streaks, however note that they do flatten out some and the coating will turn clear as it dries.  It is recommended to apply two coats of Infinity 4.1 with appropriate dry time between coats (I waited 1-2 hours).

Post from ray6: http://www.autogeekonline.net/forum/show-n-shine/37701-headlight-sealant-spar-urethane-vs-opti-coat-2-0-a-23.html

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I see lots of questions on headlight restoration on this forum relating to which system is best or what's the best product.

I'd like to share some information about headlight restoration. Although I work for a headlight restoration supplies manufacturer, the products my company distributes are not available to the retail public, so you really can't buy these products unless you are in the restoration business, and in any case I'll keep it generic.

History
Starting in 1989, auto manufacturers started switching from glass sealed beam headlights to plastic headlight modules. Part of the change was pressure from the U.S. government on getting rid of the glass. Slow speed collisions with pedestrians were producing extensive injuries not due to the physycal impact per se, but more with cuts from broken glass. Another push was that manufacturers were being pushed to produce greater mileage, which requires streamlining, including headlights.

The plastic used for the outside covers of headlight assemblies is polycarbonate, trade name Lexan (also called bullet proof glass). Polycarbonate is tough and flexible and difficult to break.

Tali lights, turn signals, etc. are made from acrylic. Totally different material. Acrylic is a petroleum based product; polycarbonate is derived from natural gas.

If someone talks about acrylic headlights, be suspicious.

If you hit a piece of acrylic with a hammer it will shatter. If you hit polycarbonate, it will bend, and maybe crack. This is why it is used.

Although polycarbonate is a great material for forming complex shapes like headlights, it has two major faults. First, it will break down with UV exposure. Secondly, it is very porous so any water that gets into the polycarbonate can freeze causing micro cracks.

In order to protect the polycarbonate from moisture and UV exposure, the headlight is coated at the factory with a protective finish. This finish is a sealer, but mostly a UV adsorber. It is applied using closely controlled procedures such as electrostatic, dip, spray, etc. It consists of first a primer then the protective coating.

It is the breakdown of this coating you see as milky or yellow. The coating is doing it's job.

The UV adsorption works by convertying UV light to heat. As the molecules heat up, they eventually break their bonds with other molecules and are no longer connected. This connection is called cross-linking.

A general rule of thumb is that because the UV coating has a finite capacity to adsorb UV, the more coating (thicker) the longer the life. So this brings up an important point. If the new coating you're applying is very thin, how long can it last?

If it's just for your own headlights, there are many kits available from dozens of manufacturers, but almost all suffer from the same issue; they don't offer a real replacement coating to replace the one you removed.

Actual headlight restoration is a two step process; remove the old protective coating and replace it with a new one. The replacement coating is where nearly all D.I.Y kits and over the counter products fail. Without a new permanent coating, all your hard efforts in cleaning off the old coating are wasted time. You'll have to do it again, only this time you're down to the raw polycarbonate and the clean up is harder to do.

Headlights are very thick, about .1 to .25 inches thick depending on size and use. Off road vehicles will have a thicker coating. Some headlights have 3 tips on them that are used for headlight alignment.

When people say they want to do headlight restoration, I first ask, is it for your own use on your own car or do you want to do it as a service for a fee? There is a big difference. If you want to restore your own headlights, you can buy a kit, use toothpaste, rubbing compound, sanding, etc. It's all the same results, get the old coating off. What differs between processes is how long will it take you and how fine a finish will you get?

Will this procedure make your headlights look like new? Probably, if you get all the old coating off and don't leave any sanding scratches (and the headlight was restorable in the first place, no cracks or internal moisture). But here's the problem. You got the old coating off. You either hand sanded, machine sanded, chemically stripped, used compound, toothpaste,grandma's secret salsa recipe, etc. Now what? If you're willing to keep a layer of good quality wax on your headlights and wax after every carwash, your headlights will probably look like new forever. If not, you need something more permanent.

On the otherhand, if you are offering headlight restoration as a service for a fee, the D.I.Y. kits and procedures are a waste of time. Sure, many of the kits will get the coating off, but are nothing more than a box of abrasives and compounds and maybe a drill attachment.

Many include some sort of secret sauce (called a shine restorer, sealer, protectant, UV coating, final coat, etc.) are nothing more than some sort of synthetic wax/polish with a limited lifetime.

Headlight restoration is becoming a huge market. All plastic headlights will deteriorate with time so virtually nearly any car manufactured after 1989 is a potenial customer, even some trucks that use plastic headlights. They will all break down, sooner or later. Since there are over 120 million vehicles in the U.S., you can imagine how big the market is and it is growing each year.

A key point in deteriorating headlights is the unspoken safety issue. Cloudy headlights are a major safety hazard as countless studies have shown.

There is a growing network of "pro" headlight restorers out there. By pro I mean they restore headlights correctly by removing the old coating and replacing it with a new, long lasting one. Products and procedures may differ, but the end results are similar; a like new looking headlight with a real, long lasting protective coating, usually with a warranty of 1 to 3 years. We know this because we sell products to them every day. There aren't many, but the numbers are growing.

The field applied new coating can never match the original, because you can't duplicate the factory coating in the field, and even if you could (primer, cure, coat, cure with UV, IR) it would be cost prohibitive.

The reason you're not familiar with these products is they are not produced for the retail market and aren't available over the counter. If you are interested in restoring headlights as a business, you should consider the following:

Separate headlight restoration into 2 parts; remove the old coating, replace it with a new one.
Removing the old coating-
Can be done with a chemical strip, abrasive, razor blade, or a combination.

Goal: Remove the old coating in the shortst time and at the lowest cost.
Most pros don't use rotary devices like electric drills. They are hard to control and can cause damage. Battery operated drills are the worst because they were never designed for this task. You'll need extra batteries, probably a car charger, etc. so it can get expensive. Instead, pros will hand sand (usually in combination with a chemical stripper) or use a small R/A sander/polisher (3" is best) available from Metabo, Groits and others.
If sanding, abrasive quality does matter. More expensive abrasives are usually cheaper in the long run because they last longer. One of the best is 3M, but overpriced in my opinion. Others are Abralon, Norton, Mirka and Indasa. It may be difficult to buy these products locally, but redily available on the internet.

Applying a new coating-
There are probably 15 to 20 coatings available, all with advantages and disadvantages. It all depends on your application limits, customer expectations, cost and market. Different applications are wipe on or spray on.

All coatings need to be cured after application. This is done in different ways. Some are 2K, curing by chemical reaction, similar to fiberglass resin. Some cure by UV exposure, either from UV lamps or direct sunlight. Many cure by oxygen absorption, such as polyurethanes (MinWax/mineral spirits is an example).

A few manufacturers are Delts Kits, Dvelup, Speedokote, Momentive, Brite Lites, Semtec, Medallion, etc. They each have their pros and cons.

If you want to do headlight restoration as a business, do your research. What's the competition in your area? Do they offer a written guarantee? How much do they charge? A pro job will probably sell for $40-160 depending on the application. Doing multiple cars on a lot is much different than doing a Lexus for a high end detailer.

When someone advertises a restoration for $30-40 and they come to you, I wonder how they make money or are they the buff and run type (sand/polish/add wax/run)?

In choosing a system and product line, you don't have to buy someone's system, although this may help when starting out. But you do have to develop the skill set and get the proper tools.

In considering a process, ask yourself the following questions:

Am I going to be mobile? If so, I must carry a bodacious air compressor to use pneumatic tools such as furnished in #M's pro kit (it also doesn't have a real protective coating). If I'll be sanding with an electric sander, I'll need to carry a generator or an inverter hooked to my vehicles battery. Inverters are problematic because car batteries are not designed for this kind of load. You really need a deep cycle battery like the type used on boats and golf carts.

Does the coating require spraying? If so, I'll have to tape and mask the headlight. If it's windy or dusty, you'll have problems. If it's indoors, like in a shop, I'll need a resperator. Spray coatings are available, but fairly expensive when you consider that that 6 oz. can for $48 really only contains about 2 oz. of usable material; 2 oz. is propellant and spraying is about 50% efficient at best.

Do I need UV lamps to cure? UV lamps are expensive with short lifetimes and will require power. Sunlight may be used, but what about cloudy days?

Will the coating cure fast enough for my customer? If you're doing jobs on a lot you usually aren't concerned with cure time. Some of thebest coatings air cure, but take 30 to 60 min. to cure. Some 2K coatings will cure in less than 5 minutes.

What kind of warranty (if any) will I offer? You beter have a pretty good idea how long your coating will last before issuing a warranty. Your warranty has to be worse case, such as a PT cruiser (horizontal surface) in Florida (strong UV) parked facing south and outside 24/7. In Florida you would probably warrant it for 1 year. In Oregon, with all other factors being equal, it would probably last 5 years.

Referrals-
What most restorers find over time is that a large percentage of new customers come to them by referrals from previous customers. A satisfied customer is your best (and free) salesman.

So, if you've read this far, you are to be congradulated in your interest level.

If you're looking into headlight restoration, your best bet is to start at the keyboard and research. Try different products and procedures. One way to learn your art is to do restorations for free to friends and family. Also consider doing restorations for non-profits such as Goodwill, Salvation Army, etc. You can learn on their cars and deduct your going rate on your taxes. There are additional markets such as government fleets, taxi companies, trucking fleets, etc.

We have a customer that does restorations for all state vehicles in his state including emergency vehicles (like light bars on police, fire and ambulences). These are made of acrylic, but are even easier to restore than polycarbonate.
ray6