dcmodels

I am talking about the clear plastic lens-cover over the front of the headlights. This also applies to fog and tail light covers, and the RDX signal-markers (side mirrors) and rear reflectors.

Without proper maintenance or protection, a headlight lens will eventually turn yellow/ opaque white or even crack. This may take 20 years, or only 1-year. It depends upon how much sunlight, for how long – it’s the UV in light that does the damage. Do you live in Las Vegas, or Seattle?

Ever wonder why some cars have headlights that are cloudy, gray, white, and opaque? Can the driver see where they are going at night? Yet other cars that are 10 years old have headlights that look like new.

Now, I have not heard of any specific problems with RDX headlights. But both my local Acura dealers offer an exchange program with refurbished headlights. And because I am seeing lots of cars in parking lots with “white” headlights, I am taking preventative care of my own RDX headlights.

SUMMARY:
Replacing one RDX headlight assembly, because of rock damage, can easily cost $1,000 dollars. Protect the headlight lens with clear urethane film.

The lenses on automotive light assemblies have a protective UV coating, to guard against oxidation (turning white). Once the UV coating is damaged, the light lens will oxidize and turn gray or yellow or white, and become basically opaque. Protect and maintain the UV lens coating and it will last indefinitely, or at least a long time. Cover the headlight lens with clear urethane film or at least apply a good wax or paint sealer each time you wash/ wax the vehicle.

There are lots of chemicals that will damage the UV protective coating, or even damage the lens itself, causing it to crack or spider-web. Consider carefully what you use on a headlight lens cover.

To restore a heavily oxidized headlight lens use one of the available aftermarket restoration kits. And unless the lens is protected with a new UV coating (sealer), the lens will require another restoration within a few months, or a year at most. Headlight sealers must be re-applied regularly, because they do not last very long. So protect the original UV coating as long as possible.

DEFINITIONS for this post:
My RDX – a 2009 Acura RDX
My Chevy – a 1998 Chevrolet S10 Blazer with 4-wheel drive
Headlight Film – clear protective film similar to that used for ‘clear bras’, but generally a little thicker
Meguiar’s Sealant – Meguiar’s Mirror Glaze #21 Synthetic Sealant 2.0 (liquid)
Meguiar’s Wax – Meguiar’s Mirror Glaze #26 Hi-Tech Yellow Wax (either paste or liquid)

PREVENTING DAMAGE to AUTOMOTIVE LIGHT ASSEMBLY LENS-COVERS:
This refers to non-crash damage to the outer surface of the clear plastic covers on light assemblies. Interior headlight damage, such as moisture leakage, is for another post.

UV (ultra-violet light) DAMAGE:
Automotive light assembly lens covers are made of various types of clear plastic (polycarbonate or ABS). Polycarbonate in particular is soft to prevent cracking (or shattering) from minor physical damage, as glass would. But polycarbonate is very susceptible to UV (ultra-violet) light degradation – like human skin cancer from over exposure to the sun.

Some types of plastic are more prone to UV damage than other types. It depends upon how much UV protector is mixed into the plastic itself, before molding. But since this is not a chemistry class, there is no point in speculating why some car manufacturers use one type of plastic or another. But it does explain why some particular models of cars suffer from headlights so ‘white’ and opaque that you wonder if the driver can see at all at night, while other car models that are 10 years old have headlights that look like new.

It is my understanding that all head (and tail) light covers have a clear UV protective coating. Think in terms of human ‘sunscreen’. Once this lens UV protective coating is damaged or removed, it takes only a short time for the lens to oxidize and turn white. And how thick is this coating? I have no idea, but probably on the same order as the body paint clear-coat, which has an approximate thickness of 25.4 microns = 1.0 mil = 0.001 inches. A 3x5 inch paper note card is typically 0.010 inches thick.

Physical ‘sandblasting’ from normal driving will damage the headlight UV protective coating. The solution is to cover the lens with one of the many available clear films. Think about it. If your windshield looks like the surface of the moon, how do you expect the much softer plastic headlight lens cover to survive?

Specific films are made for headlights, similar to the films used for ‘clear bras’ on front fenders and hood front-edges. The headlight films will not only provide some level of protection from bugs, sand, and small pebbles but also UV protection.

The cost to have a ‘professional’ cover my RDX headlights and fog lights was around $80, much less than $2K to replace a couple of headlights broken by rocks kicked-up by cars I may be following. My film looks good after 3 years and 25K miles.

WHICH HEADLIGHT FILM?
Based on what I have read, I think that 3M clear film may be the most durable. Apparently it can be waxed, or even buffed with Meguiar’s Scratch-X to remove minor scratches or blemishes. However, I could not find someone to install 3M film on my own RDX, because the headlight film is pre-cut to size. But for ease of installation, most installers want to apply an oversize piece of film, then cut-to-size on the headlight, rather than positioning an exact size piece of film.

My RDX headlights were covered with the CLEARBRA™ brand of film, the same stuff as used on the hood and fenders. The brand does not have a different film for headlights. This brand is available in only about 5 states. I simply went to the place recommended by the car dealer where I purchased my RDX, because that is where my car dealer has their new cars done.

When choosing a film for your own headlights, you will want to explore the various brands and options, and discuss them at length with your film installer. And ask about the warranty.

CHEMICAL DAMAGE:
There have been multiple TSBs (technical service bulletin) from GM stating basically that many chemicals will damage the plastic light lens cover, causing yellowing and crazing and cracking.

Specifically mentioned are: bug and tar removers, rubbing compounds, tire cleaners, cleaner waxes, and strong car wash chemicals. The GM TSBs cover all GM models from the late 90s through the current models.

I have no specific technical information regarding the UV protective lens coating. Based solely on my observation and experience, the coating is a clear paint, similar to the clear coat over the color paint on the body. I can see on my Chevy 3rd brake-light cover, that the clear-coat is peeling away. And on one of the Chevy taillight covers, I can see an area where the coating has been buffed away (because I used Meguiar’s Plast-X plastic polish in an attempt to remove a scratch – wrong move). Still, I have no clue what the UV coating really is, or how it is applied, or why the coating from some manufacturers lasts much longer than that from other car makers.

If the light lens UV coating is really paint, it should be clear (pun intended) why the cautions stated by GM would easily damage the lens UV protective coating. Those same chemicals have the potential to damage body-paint clear-coats.

If body paint clear coat is damaged, or overly thinned by too aggressive compounding, the clear coat will rapidly fail from UV, followed by failure of the color coat under it. GM had a period of problems with car body paint failures during the 90s, usually on the tops of fenders, hoods, tops, etc. Those color-paint failures were due to clear-coat failure.

The typical clear-coat over color-paint is 1.0 – 2.0 Mil (25-50 microns) thick.
“The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow before the paint warranty becomes void: Chrysler – 0.5 Mil (12µ) Ford – 0.3 Mil (7.5µ) GM – 0.5 Mil (12µ) (Source - Automotive International)”

HEAT DAMAGE:
The GM TSBs mentioned in the previous section, also state that a headlight lens cover can be damaged (warped/ distorted) by overheating. This can occur while the car is being serviced, if the DRL headlights are on, and the headlights are covered by a workman’s fender protector. Keep this in mind when working on your own vehicle.

QUOTED FROM a GM TSB: “The degradation of the lens can be unnoticeable at first and eventually become hairline cracks in the lens. In extreme cases, it could cause the lens to deform. This damage can also be caused by aftermarket shields that are often tinted in color.[ed: I do not know what kind of shields is referenced, possibly those styling eyebrow top covers?]

Once a heat buildup is generated by the headlamp, a degradation of the headlamp lens begins. This degradation of the lens can be unnoticeable at first and eventually manifest as spider cracks. In more extreme cases, it will begin to melt the lens of the headlamp.”

Overheating of the headlight lens cover can also occur if the aftermarket protective film used is too thick, or if a small area around the edges of the headlight assembly is NOT left uncovered. Most reputable film installation shops will be aware of both problems.

And if aftermarket higher watt bulbs are used (100w or 130w), heat build-up can also be a problem, especially when film is applied.

MAINTENANCE of LIGHT ASSEMBLY LENS-COVERS:
You want to maintain the existing UV protective clear coat on the lens covers. Once it is gone, you must either replace it (the protective coating), or maintenance becomes a regular recurring chore.

HEADLIGHT FILM MAINTENANCE:
OMG. First you covered the headlights with film to protect the headlight, now you have to maintain the film itself? Not really. You can simply replace the film every few years when it becomes worn. Some installers will warranty the film for the ‘life-of-your-car’. Ask before paying.

Headlights can be covered with film. Taillights can also be covered with film, but I have never done this. There are several brands of film used to cover headlights. Often the same film used for a ‘clear-bra’ on the hood/ fenders, is also used to cover the headlights. Ask how the film that you purchase is to be cleaned and maintained. Also, some films can be damaged by the chemicals in automatic car washes. You are paying, so ask.

WARNING NOTE: the following is the recommended maintenance procedure for the CLEARBRA™ brand of film used on my own RDX. Check with your own film installer for maintenance products for the film used on your RDX.

To remove stubborn bugs, use 3M Adhesive and Wax Remover, aerosol. Yes, I remember the GM TSB cautions against strong chemical use on their headlight lenses. So I am careful to use it only on the film, not directly on any headlight or tail-light lens. Meguiar’s Scratch-X can be used to buff-out light scuffs and mars. Any good light-colored car wax or paint sealant will protect the film. Heavily colored waxes may stain the film. Meguiar’s #21 is a dark purple, but has never stained my own headlight film.

I use the above method when I do not want to wash the headlights by hand with car wash soap, messing up my car wax-job. And I do not worry because my headlight film is warranted for life.

HEADLIGHT UV COATING MAINTENANCE with WAX or PAINT SEALANT:
My film installer would not put film on my Chevy headlights. First, there are three (projecting) aiming ‘nipples’ on the lens cover, and the installer just did not want to deal with them for the $50 or so he charges. Second, my Chevy headlights were already 10 years old when I asked, and the headlight surface (in miniature) looked like the surface of the moon (from road sandblasting). I think the installer did not believe that the film would stick (lay-down) properly.

And yet, the Chevy headlights look perfectly clear (except for the tiny pits). Why? Because every time I wax the car, I have also waxed the headlights and taillights. You must decide for yourself if you will use car wax or paint sealant to protect the light lenses on your own car.

But remember that the GM TSB (described above) cautions against using cleaner (abrasive) waxes. I use only Meguiar’s #26 Yellow Wax or Meguiar’s #21 Sealant on the light lenses. These car waxes are non-abrasive, and provide UV protection. All my Chevy light lenses are in good condition after 14 years of being parked all day outside at work: rain, shine, or snow. Well, except for the Chevy 3rd brake-light, which for some reason I never thought to wax until one day I noticed that most of the clear-coat was gone, and the lens was pretty oxidized.

Meguiar’s products are available from NAPA or an automotive body shop. Other products may work as well, but these are the only products that I have tried.

The newer paint sealants contain synthetic cross-linking polymers which actually become ‘part’ of (bond-to) the surface to which they are applied. In effect they become a secondary sacrificial layer. Durability is much greater than the typical car wax. I can only comment that my experience with Meguiar’s #21 Sealant is that it lasts longer than their #26 Yellow Wax.

HEADLIGHT UV COATING MAINTENANCE with LENS SEALERS:
There are currently various chemicals specifically marketed to be used to maintain headlight lens covers. These are called headlight-sealers. I have never used one of these products.

The two headlight lens sealers I have seen locally, are BLUE MAGIC Headlight Sealer and MEGUIAR’S Headlight Sealer. Read the labels carefully for proper use.

REFINISHING a LENS-COVER:
There are certainly hundreds if not thousands of online threads online describing various methods of restoring and maintaining headlights. Check-out a few for yourself.

REMOVING VERY LIGHT OXIDATION:
On one of the taillights on my Chevy, the UV protective covering on the backup (clear) light lens is degraded and the lens slightly oxidizes between car washes. I use Meguiar’s #21 sealant to clean and protect the lens.

REMOVING LIGHT OXIDATION:
My Chevy third braking taillight lens (center high) – the UV protective covering is almost completely gone, and the lens cover obviously oxidizes. I use Meguiar’s #21 sealant or Meguiar’s #26 wax to clean and protect the lens. Either lasts from 6-12 months depending upon the weather, and how often the Chevy is washed.

I am just too lazy to restore and refinish that light-lens. The Chevy is 14 years old, and it would require removing the light assembly to work on it, probably leading to a leak.

Note that the Chevy third brake light UV coating is still present (partly) on the vertical surfaces, and completely gone from the top (horizontal) surface. This is common since horizontal surfaces get more sunlight. That is why sloped/ slanted headlights can be oxidized on the top half, while the front/ lower more vertical half still looks good, because the UV coating is intact on that portion.

REMOVING MODERATE OXIDATION:
On one of the taillights on my Chevy, the UV protective covering on the backup (clear) light lens was mostly gone. The backup-light lens had oxidized and was turning white. Yes, a clear lens was turning ‘white’. Well, the lens was turning opaque, and diminishing the amount of light behind my Chevy.

I used Meguiar’s Plast-X plastic polish to remove the remaining UV coating and oxidation. Then I protected the lens with Meguiar’s #21 Poly Sealant, because that is what I use on the other light lens covers, and because it seems to last almost a year where I live.

The Chevy backup-light on the other side was in better condition, because that was the side that was rear-ended (crashed) 5-years ago. The taillight was replaced by the body shop during repair. So that taillight is newer (5 versus 12 years old).

REMOVING HEAVY OXIDATION and SCRATCHES/ PITS due to SANDBLASTING from ROAD DEBRIS:
This requires an aftermarket refinishing kit, especially the ones which use sandpaper. I have never used one of these kits, as my light covers have not degraded that much, basically only the center backup lens cover on my Chevy.

In reading the various online threads concerning headlight restoration, the people who do this professionally say that it takes them 1-2 hours (for both). And the charge is $40 to $80 generally. Some dealers will also restore your headlights, costing from $150 up. (But the dealer is just going to sub-out the work)

UV SEALER USE AFTER A REFINISHING PROCEDURE:
After headlight lens restoration, monthly maintenance is required, else the lens cover is just going to oxidize again in a few months. Maybe longer, depending upon the car model, but not more than 1-year. Some car models are much more prone to headlight lens oxidation than others.

There are special chemicals (sealers) to be used to maintain the headlight lens, after a refinishing kit has been used. And the maintenance sealer chemicals must be used regularly and often. Otherwise the lens will oxidize again within a couple of months.

The following thread describes a restoration procedure and ‘home-remedy’ lens sealer that lasts for 2-years without maintenance. Use at your own risk, as I have not used this procedure myself. You really need to start with the first post, and read from there, to clearly understand the procedure.

http://www.autogeekonline.net/forum/...t-idea-84.html

The other option that I have read about is to paint a restored headlight with a two part catalyzed polyurethane clear (any body shop can do the painting). I have no personal experience with this procedure.

EXAMPLE:
Here is what can be achieved with wax/ paint sealant only, when the lens clear coat has deteriorated, and some oxidation has occurred. No sanding, polishing, etc. was done.

The following pictures are of the 3rd brake light on the top of my Chevy 4x4. As can be seen, most of the clear coat has peeled away. The BEFORE pictures show how the brake-light has been for the past 6-months, all of this past summer in 100+ degrees sunshine (I’m lazy). Where the clear-coat is missing, the plastic has obviously oxidized, and begun to deteriorate.

The AFTER pictures are after I applied Meguiar’s #21 paint sealant, when I washed and waxed the rest of the vehicle. I did not remove the remaining clear-coat from the light. If you look closely, you can see the demarcation between the part of the light with and without clear-coat. I did nothing more than wash the light (with car-wash soap), and apply two coats of #21 sealer, using firm pressure. Synthetic paint sealers bond-to and actually become one with the part to which they are applied.

The surface of the brake-light reflects a lot of sunlight, so it was difficult to get a more clear picture than what is shown here. The white reflections on top are clouds, and the dark reflections are my hands and the camera. The brake-light seems to be ‘floating’ because the truck is white.

PICTURE: wide view


PICTURE: detail

---eof

SinCity

Good tips. The UV coating on the Acura does not seem to hold up well as compared to my 2004 C320. The C320 headlight has never been treated and the coating is intact. Whereas my RDX failed in 3 years of ownership. I now use a liquid was which seems to hide the edges of the peeling edges of the coating. Both cars garaged and my dad now has my C320 which is also garaged.

dcmodels

UPDATE – alcohol damages HEADLIGHT LENS

Isopropyl alcohol will damage any unpainted plastic parts, including taillights, turn signal lenses, reflectors, etc., according to Acura TSB 96-010 Minor Paint Finish Repair. The TSB recommends a 50/50 solution of isopropyl alcohol and water for paint cleanup, after paint repair. I suppose other types of alcohol may also cause damage, and damage to a headlight lens.

http://www(dot)acura(null)world(dot)com/tsb/TSX/b96-010.pdf

This information is consistent with the TSB from GM mentioned in my original post, concerning possible chemical damage to headlight lenses, from common automotive detailing products.

While you may not be using alcohol itself, there are many automotive cleaners and polishes that may contain alcohol. You will need to read the MSDS for any products that you wish to use on plastic parts.

---eof