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Thread: Do projectors degrade?

  1. #1

    Default Do projectors degrade?

    I see that it is recommended to purchase entire replacement headlight housings around here instead of just polishing the lens because the reflector surfaces are likely also shot. Do projectors also degrade like the reflective surfaces in reflector design headlights?

  2. #2

    Default Re: Do projectors degrade?

    Projector headlamps contain reflectors (you just can't see them from the front) so the answer is yes. In fact, reflector degradation can happen faster and to a worse degree with projector lamps because the reflectors are smaller and therefore closer to the hot bulb.

  3. #3

    Default Re: Do projectors degrade?

    Are you aware of any upcoming advances that will address the issue of headlight degradation? Since we're keeping our cars longer and longer (average car in US fleet is almost 12 years old), it seems prudent that manufacturers try to ensure that headlights stay in good shape for longer. Especially since most people in the US don't care about the headlights unless a bulb is burned out. Yellowed? No problem. Hazy? No problem. Moisture inside? No problem. Bulb burnt out? Well, I don't want to get a ticket...

  4. #4
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    it seems prudent that manufacturers try to ensure that headlights stay in good shape for longer.
    It would seem so, but until there are toothy laws to ensure it, it won't happen. Some states have inspection programs and should reject cars based on yellowed/crazed/hazed exterior lenses, but seldom do. And to establish standards of reflector performance after X years, and for state inspections to inspect for that seems pretty far-fetched.

    The consumer is somewhat voiceless and powerless here, or if not those, then complacent ("especially since most people in the US don't care about the headlights unless a bulb is burned out"). Remember as well that automakers aren't after the "buy 'em and keep 'em" crowd (Look how many new Corollas Toyota sells every year, even. And those are the cars people KEEP).

    There's little internal incentive for automakers to make them better than what is required. They're after the people who get a new car every year or two-- and they get those sales. For those people, what is required is good enough. They'll sell the car or trade it in on the new one-- and the next owner of the car gets saddled with the aging headlamps. And what can they do? They can't either can't afford the new car, or they have other financial priorities-- they'll take the cheap car that runs and has "cold A/C".

    Manufacturers will keep getting those first sales, and unless one of the major manufacturers does something differently, setting themselves apart, they'll all keep doing what "works".

    Yes, it SHOULD happen that headlamps are built to last longer than they do, but it won't be out of the manufacturers' kindness and it won't be the result of any new laws any time soon because that takes time. And in the meantime, maybe a new plastics technology will be developed that somehow makes longer-lasting lenses cheaper to produce, but don't hold your breath. What's "working" now has been "working" since the '90s when polycarbonate started overtaking glass.

  5. #5

    Default Re: Do projectors degrade?

    Thanks for the information guys. I'm asking because I'm about to pick up a 2011 Prius with hazy and yellowed headlights in Florida. I'll be driving it up from FL to NY. The first time I did that in a car, I was contemplating stopping at a rest station for a few days and ordering an HID kit to the rest station--I couldn't see worth a damn and it was extremely frustrating to have to stop at night when I could have otherwise completed the trip within a day.

    This time, I'll be going down with a pair of 9011s, and perhaps a cordless drill so I can at least polish the lights before heading up.

  6. #6
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    The first time I did that in a car, I was contemplating stopping at a rest station for a few days and ordering an HID kit to the rest station--I couldn't see worth a damn and it was extremely frustrating to have to stop at night when I could have otherwise completed the trip within a day.
    You still wouldn't have been able to see well, just in a different way-- and would have made things worse for others. Good thing you didn't!

    Headlamps ruined by the Florida sun may have yellowing that is deep enough to not polish out except perhaps by dangerously thinning the lens that the slightest impact will perforate the lens. I'd recommend replacing them with new lamps as soon as possible.

  7. #7

    Default Re: Do projectors degrade?

    Quote Originally Posted by Alaric Darconville View Post

    Headlamps ruined by the Florida sun may have yellowing that is deep enough to not polish out except perhaps by dangerously thinning the lens that the slightest impact will perforate the lens. I'd recommend replacing them with new lamps as soon as possible.
    How thick are the lens usually anyway? 5 mm?

  8. #8
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    How thick are the lens usually anyway? 5 mm?
    From about 3.175mm to 6.35mm. Depending on the thickness of the lens, perhaps the yellow hasn't gotten in so deep-- but polishing off enough to get to the clear part may reduce the strength. Also consider that some yellowing will occur from the inside surface out-- the UV that enters the lens is reflected back out; that side of the lens may have less/NO UV protection.

  9. #9

    Default Re: Do projectors degrade?

    So what is the main mechanism of reflector degradation? Exposure to UV? If so, why do the internal, non-visible surfaces of a projector degrade? I know that halogens emit UV, but isn't that filtered out by the glass capsule?

  10. #10

    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    So what is the main mechanism of reflector degradation?
    Heat breaks down the reflector overcoat, and then the reflective material itself oxidizes.

  11. #11

    Default Re: Do projectors degrade?

    Quote Originally Posted by -Virgil- View Post
    Heat breaks down the reflector overcoat,
    So LED projectors can worry less about degradation, right? The heat of an LED chip goes out the back rather than toward the reflective surfaces, correct?

    Quote Originally Posted by -Virgil- View Post
    and then the reflective material itself oxidizes.
    From what I understand about LED headlights, there isn't much of a point to allowing user access.

    Not as if the user can replace the chip inside. So, is it possible to create a non-oxidizing environment inside a LED headlight? Do any manufacturers do this already--i.e. they put nitrogen in the headlight assembly as opposed to regular air? I already (involuntarily) paid extra for nitrogen in my tires at the dealer. Surely the manufacturers can put pure N2 in their headlights as well. Or should I take my idea to the nearest patent office? Would my idea have any effect on the rate and extent of headlight degradation?
    Last edited by Ls400; 10-07-2018 at 04:15 AM.

  12. #12

    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    So LED projectors can worry less about degradation, right?
    Different degradation mechanisms affect different parts in LED headlamps. For example, there are often plastic optics in very close proximity to LEDs with very high blue-violet output and some amount of UV. Once these plastic materials begin -- just begin! -- to degrade, it's a cascading vicious cycle and the degradation accelerates.

    From what I understand about LED headlights, there isn't much of a point to allowing user access.
    Correct.

    Do any manufacturers do this already--i.e. they put nitrogen in the headlight assembly as opposed to regular air?
    No. Headlamps are not sealed entities, they must have air exchange.

  13. #13
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    Surely the manufacturers can put pure N2 in their headlights as well. Or should I take my idea to the nearest patent office? Would my idea have any effect on the rate and extent of headlight degradation?
    Headlamps (other than sealed beams) are not airtight. An airtight headlamp, regardless of fill gas (plain air, N, CO2, etc) will run into problems, such as when the fill gas expands with heat-- and then any tiny break in the seal could mean moisture gets in and then never gets out. Your idea will certainly increase the rate and extent of headlamp deterioration.

    Sometimes people respond to water fogging on the inside of their headlamps by attempting to seal them with all kinds of things, like epoxy resins, windshield urethane, bathtub silicone*, taping up joints-- this just exacerbates the problem. The water fogging usually occurs because a vent or vents aren't functioning.

    *And silicone sealants have problems all their own with respect to headlamps

  14. #14

    Default Re: Do projectors degrade?

    Quote Originally Posted by Alaric Darconville View Post
    Headlamps (other than sealed beams) are not airtight. An airtight headlamp, regardless of fill gas (plain air, N, CO2, etc) will run into problems, such as when the fill gas expands with heat-- and then any tiny break in the seal could mean moisture gets in and then never gets out. Your idea will certainly increase the rate and extent of headlamp deterioration.
    Is that why sealed beams pretty much don't exist on modern vehicles?

    Sometimes people respond to water fogging on the inside of their headlamps by attempting to seal them with all kinds of things, like epoxy resins, windshield urethane, bathtub silicone*, taping up joints-- this just exacerbates the problem. The water fogging usually occurs because a vent or vents aren't functioning.

    *And silicone sealants have problems all their own with respect to headlamps
    Does the heat generated by the headlamp cause the moisture to evaporate and thereby more easily circulated out?

    What's the issue with silicone sealants?

    Quote Originally Posted by -Virgil- View Post
    Different degradation mechanisms affect different parts in LED headlamps. For example, there are often plastic optics in very close proximity to LEDs with very high blue-violet output and some amount of UV. Once these plastic materials begin -- just begin! -- to degrade, it's a cascading vicious cycle and the degradation accelerates.


    Lawyer voice: Would you be in support of publicizing the relevant performance results of headlamps that have been subjected to simulated aging? Given that the average car in the US fleet is 11.6 years old, do you think it would be useful to publicize results regarding how headlights perform both when fresh out the factory and after 11.6 years of simulated use?
    Last edited by Ls400; 10-09-2018 at 12:07 AM.

  15. #15
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    Is that why sealed beams pretty much don't exist on modern vehicles?
    Not really. Sealed beams just aren't as stylish and cool and high-tech looking as composite headlamps. Also, replacing a bulb rather than an entire lamp is cheaper.

    Does the heat generated by the headlamp cause the moisture to evaporate and thereby more easily circulated out?
    Does a kettle sometimes boil dry?

    What's the issue with silicone sealants?
    The outgassing when it cures is deleterious to the reflective surfaces.

    We're not asking for a headlamp to live the life of a car (nothing really "lives the life of the car" except maybe the rear armrest), or even 11.6 years, it's just that the current requirements are pretty lax.

  16. #16

    Default Re: Do projectors degrade?

    Quote Originally Posted by Alaric Darconville View Post
    We're not asking for a headlamp to live the life of a car (nothing really "lives the life of the car" except maybe the rear armrest), or even 11.6 years, it's just that the current requirements are pretty lax.
    Are there any requirements for a headlamp's reflective surfaces' lifespan? I'm a little confused by what you mean by "current requirements are pretty lax."

  17. #17
    Moderator Alaric Darconville's Avatar
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    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    Are there any requirements for a headlamp's reflective surfaces' lifespan? I'm a little confused by what you mean by "current requirements are pretty lax."
    The requirement for the outer lens itself is incredibly lax.
    S5.1.2Plastic materials used for optical parts such as lenses and reflectors shall conform to SAE Recommended Practice J576 JUL91, except that:
    (a) Plastic lenses (other than those incorporating reflex reflectors) used for inner lenses or those covered by another material and not exposed directly to sunlight shall meet the requirements of paragraphs 3.3 and 4.2 of SAE J576 JUL91 when covered by the outer lens or other material;
    (b) After the outdoor exposure test, the haze and loss of surface luster of plastic materials (other than those incorporating reflex reflectors) used for outer lenses shall not be greater than 30 percent haze as measured by ASTM D 1003-92, Haze and Luminous Transmittance of Transparent Plastic;
    (c) After the outdoor exposure test, plastic materials used for reflex reflectors and for lenses used in front of reflex reflectors shall not show surface deterioration, crazing, dimensional changes, color bleeding, delamination, loss of surface luster, or haze that exceeds 7 percent as measured under ASTM D 1003-92.
    The outdoor exposure test is essentially three years of weathering in Arizona or Florida. Harsh environment, sure-- but still too short at time for required safety equipment.

  18. #18

    Default Re: Do projectors degrade?

    Quote Originally Posted by Ls400 View Post
    Is that why sealed beams pretty much don't exist on modern vehicles?
    No, sealed beams pretty much don't exist on modern vehicles for the same reason that most other technology first launched in 1940 and last substantially upgraded in 1979 doesn't exist on modern vehicles. They're obsolete from a technical and design/style perspective, and for better and worse the industry has moved elsewhere.

    Does the heat generated by the headlamp cause the moisture to evaporate and thereby more easily circulated out?
    Yes.

    Would you be in support of publicizing the relevant performance results of headlamps that have been subjected to simulated aging?
    No, I would be in support (actually I AM in support!) of making the regulations appropriately stringent with regard to headlamp durability of performance and compliance.

    Given that the average car in the US fleet is 11.6 years old, do you think it would be useful to publicize results regarding how headlights perform both when fresh out the factory and after 11.6 years of simulated use?
    No. I think it would be useful to require that headlamps last a reasonably long time.

    Are there any requirements for a headlamp's reflective surfaces' lifespan?
    There are environmental tests required for headlamps, which you can read about in section 14.6 of FMVSS 108. Clearly, as a walk down any street will show, the requirements are not adequate to assure headlamp durability reasonably commensurate to the ordinary service life of vehicles.

    The 3-year Florida and Arizona tests are problematic. Actual headlamp lenses aren't tested, just test plates of polycarbonate materials and coatings. And extending the test beyond 3 years would worsen an existing problem, that the newest state-of-the-art materials are not allowed (the newest allowed materials are 3 years out of date). And the allowance for 30% haze is ridiculously lax, given what that amount of haze does to a headlamp's seeing (less) and glare (more) light output.
    Last edited by -Virgil-; 10-09-2018 at 10:25 PM.

  19. #19

    Default Re: Do projectors degrade?

    Why can't they just do accelerated lifecycle testing instead of waiting an actual 3 years?

  20. #20

    Default Re: Do projectors degrade?

    The rest-of-the-world regs use accelerated testing, and they have problems with lens degradation, too. The real problem is the auto industry won't pay for the really good, durable materials and coatings unless and until they're forced to, and any such force will have to come from the top down (governmental edict). It's unfortunate that the world's governments haven't addressed this issue, because it is a direct and primary cause of pedestrian deaths.

  21. #21

    Default Re: Do projectors degrade?

    Quote Originally Posted by -Virgil- View Post
    The real problem is the auto industry won't pay for the really good, durable materials and coatings unless and until they're forced to, and any such force will have to come from the top down (governmental edict). It's unfortunate that the world's governments haven't addressed this issue, because it is a direct and primary cause of pedestrian deaths.
    This is why I asked earlier about your thoughts regarding "naming and shaming" automakers who don't use durable materials by publicizing the result of lifecycle testing. I think it's pretty clear that the IIHS has already done a pretty decent job of forcing automakers to improve headlight aim at the factory, and they did it without changing a single regulation. Perhaps a rating of Good/Acceptable/Marginal/Poor for how a car's headlights will be in 10 years would shame automakers into aiming for Good ratings instead of Poor?

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