Guide to headlight restoration

[ray6]

Guide to headlamp restoration
Background: Been restoring headlights for about 4 years. In a previous life, I was an electrical engineer and technical writer, so my articles are long winded and anal. I apologize in advance.
Products tried or evaluated: Probably every product known to man
Customer base: Everything from buy here/pay here to retail ?Lexus? customers
Pricing model: $20/vehicle (multiple vehicles at 1 location) to $120 mobile
Having learned a few tricks over the years, I?d like to share some thoughts with others either presently restoring headlights or thinking of doing so.
First of all, I don?t believe there is a ?one size fits all? approach to restoring headlights. It?s a function of each situation and is based on time, customer?s expectations, price and longevity. For example, at a low end used car lot, they want it to look good, be fast and cheap, and last long enough to get it off the lot. At the other end is a Lexus owner who wants their headlights to look like new and last for years.
No single approach can meet these two situations. We use different procedures and products for different customers.
Basics
Since the late 1980's, most automobile headlights have been made out of polycarbonate, a type of plastic. This plastic gives auto makers greater design freedom than conventional glass headlights. Polycarbonate is impact resistant and easily formed into complex shapes.
Unfortunately, polycarbonate is also very porous and easily damaged by ultraviolet exposure from the sun. To seal and protect polycarbonate, headlights are coated with a protective outer coating when manufactured. It is the breakdown of this coating which causes yellowing and cloudiness. Until fairly recently, the only solution was to replace the entire headlight assembly, which can easily cost hundreds of dollars.

As headlights deteriorate, less light is projected forward where you need it. The ability to see clearly can be reduced 75% or more creating a major safety hazard. This is especially dangerous during bad weather. Here?s what it cloudy headlights look like. When headlights get this bad, many drivers drive with their high beams on in order to see where they are going.

The original protective coating applied by the manufacturer absorbs ultraviolet rays preventing them from reaching the polycarbonate and also seals out moisture. While doing its job, this coating slowly oxidizes, causing it to become cloudy and yellow. This is what you are looking at when you see a yellow and/or cloudy headlight.
At the factory, the polycarbonate is coated with a primer, baked, then sprayed with a thick protective coating and cured with ultraviolet. This process cannot be efficiently duplicated in the field.

To restore headlights to full clarity the oxidized coating is removed, then replaced with a new coating. Just stripping the old coating off will leave the polycarbonate exposed to ultraviolet and moisture and will quickly deteriorate.

Any product that does not replace the protective coating with a new one is a short term solution. Without replacing this coating, the headlights will quickly deteriorate since there?s no protection. Wax protection is temporary on headlights just the same as it is on paint.

If a headlight does not contain internal damage and is not cracked, punctured or contain deep scratches not repairable by sanding, it can be restored to look like new. It?s just a question of time and money.

Here?s the procedure we use:
1) Evaluate the headlight.
a. Is it restorable?
b. What constraints do I have?
i. Time allowed, price, customer?s expectations

2) Protective coat adhesion.
a. Can it be chemically stripped?
b. Abrasive stripped?
c. Combination?

On this forum see the same type of questions such as, what is the best way or which protective coating should I use or how long will it last? I?ll try to answer some of these questions.

Best way/best coating- depends on the customer and condition of the headlight. Choice of coating is the same. Do you have to give it a warranty? How long?

How long will it last- polyurethanes, 6 months to 3 years. Specialized coatings, 3 years or more.

Durability- When you do research you will see postings indicating coating lifetimes all over the place. Here?s why:

If you?re talking about solvent based urethanes (such as Minwax/mineral spirits mix) there are 3 main factors:
1. UV exposure: A headlight exposed to the sun every day will fail in a matter of months. Also, the angle of the headlight plays an important part. The less vertical, the more exposure.

2. Coating thickness: The thicker the coating, the more UV protection. The flip side of this is the heavier the coat, the more difficult it is to apply correctly.

3. Surface prep: The surface must be absolutely clean with some ?tooth? for the urethane to hold on to.

If you?re talking about synthetic coatings/polishes/wax, it?s the same as applying to paint. It?s temporary. Why would it be any different on headlights?

We don?t use much polyurethane coatings any more. Only on quick and cheap restorations or on acrylic plastic such as tail lights, backup lights, turn signals, emergency vehicle lights, etc. Most of our restorations use specialty coatings developed for this purpose. These products are not cheap, but represent less than a dollar per restored headlight. If you do use this type of product, make sure you do the following:

Moisture/wax/silicone is your enemy. Don?t use any compound containing wax when polishing. Don?t use any wax coated cups to mix coating in. Don?t use foam brushes to apply (will leave air bubbles).

Aggressively scrub the headlight with pure alcohol, not any mixture that contains water such as rubbing alcohol (30%) water. Use lint free towels to scrub. Use a 3000 grit polishing pad as the last step. It?s not for appearance. Urethanes are famous for filling in sanding marks. It?s for tooth. Something for the coat to adhere to.

Here?s 2 examples we did last year for a training DVD.

The first is from a late 90?s Ford product. This is probably the worst case you will ever see. Although this headlight looks bad, there was no moisture inside or any internal damage. No through cracks or severe scratches.

Step by step procedure:
1. Chemical strip (removed about 90% of old coating.
2. Razor blade scrape of pock marks in upper right.
3. Wet sand with 320 grit disk with sanding aid (required to remove razor blade damage).
4. Wet sand with 500, 1000, 2000 then 3000 polishing pad.
5. Coat with water bourne 2K coating. Total time about 15-20 minutes. Cost, about $3 per headlight.

We would warrant this headlight for a minimum of 3 years.
Second example is an early 2000 GM product. The damage is superficial and only required chemical strip, 3000 grit polish, and same coating as above. Took less than 5 minutes. Cost about $1.50 per headlight.

These are the two extremes.

If you find this posting helpful, or want more information, let me know. Also, some of the products we use are not sold by AG, so I can?t post them so don't ask.

Ray6

[Capa1970]

Very fascinating and interesting. Thanks for posting.

[pepusv]

Very interesting...but you got me lost at:
"Coat with water bourne 2K coating"

What/who sells this product and how is it applied?

[ShineMyCar]

I used this 3M kit

3M Headlight Lens Restoration System, headlight polishing kit, restore yellow headlights, 3M plastic polish

You need to buy some Auto tape to protect the paint around lense, and sealant but the process is pretty simple. You use a drill for the sanding disc. Sand progressively finer sandpaper followed by polish. You can turn on headlights between steps and see any scratches you may have missed as you proceed through the steps.

Took me about 30-40 min per light start to finish. I used Klasse AIO as a sealant because I had the stuff. After I know more about how long it lasts, I'll give some feedback on that. But the lenses went from dull yellowish to crystal clear. There were a few scratches in one spot of lense that I can't get to, but the results were REMARKABLE....

10 yr old car, I was expecting some oxidation inside of lense, but it ended up looking like new.

[addysdaddy]

Is it possible to get a good result by compounding with say M105, then polish with M205 and seal it BFCS? Or should I take 2000 grit sand paper first and wet sand the lenses?

[ShineMyCar]

Is it possible to get a good result by compounding with say M105, then polish with M205 and seal it BFCS? Or should I take 2000 grit sand paper first and wet sand the lenses?

3M Kit Grit Progression is 500, 800, 3000, Polish.

[GalKonz]

Very interesting...but you got me lost at:
"Coat with water bourne 2K coating"

What/who sells this product and how is it applied?

I am interested too.

[ray6]

It's applied by wiping on with a foam applicator. Cannot promote it on this website, but with a little googling, you can probably find it.

If not, send me a PM.

[Twister]

How are you scrapping off with a razor? What are you using to chemically strip?

Could you PM me what you use as as UV protectant?

[FUNX650]

Hi ray6...

I was wondering:
-Is something like the Infinity 4.1 system: A waterborn 2K automotive CC?
-If so...Would it be as good as, or perhaps a better choice for HLR than say, using the
DuPont's/PPG's offerings of either: solvent-born/high-solids,
1K or 2K, automotive CC?

Thanks in advance for any info/recommendations you
may have in regards to the above topics.



Bob