What causes headlight lenses to fog over?
- Thread starter Bamaro
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You have a leak and it is forming condensation. Air and water vapor is getting in there.
Or are you talking about foging on the outside? My headlights get really hot and brun that stuff off.
Or are you talking about foging on the outside? My headlights get really hot and brun that stuff off.
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When new, the clear plastic lenses have a protective coating on them. Unfortunately, sun, weather, etc. and just time tends to deteriorate this layer which rapidly allows the fogging,yellowing &/or hazing of the lens. This is why restoration of the lens is only good for a limited amount of time although protective coatings are available. IMO, this is just another example of a cheap alternative to glass lenses that went bad. Some of the worst cases I've seen are the late 80's/early 90's cars (especially Fords, Subarus and GM trucks.) As for good protective coatings, I'd first check out what the private-pilot small aircraft use on their clear plastic - most of the retail automotive products these days is just more hype and promises.
Sunlight does it. You can polish them clear and then shoot some plastic-friendly clearcoat over them. When I did my dad's '96 Taurus, I used rubbing compound to clean the yellow haze off, then used an orbital buffer + plastic polish. When I was satisfied they were as clear as they were going to get, I washed and wiped 'em down with prepsol then painted with a few coats of clearcoat applied about 10 minutes apart. That was a couple of years ago and they're still clear.
New they have a uv resistant coating, that wears off, and the UV yellows the lenses.
Two good options above. Also, new lenses would be an option I might consider.
Two good options above. Also, new lenses would be an option I might consider.
A little trick I've learned over the years that only works if the UV coating hasn't broken down and the lenses already started yellowing: Once a week go over the headlights with Pledge furniture polish. Pledge has a UV protector in it. It won't last long, hence you have to do the lights once a week. But it works.
Originally Posted By: Bill888
IMO, this is just another example of a cheap alternative to glass lenses that went bad.
Exactly. My mother has a 1991 Honda Accord with glass headlights. Clear as the day she bought the car (ok..maybe a few nicks). Compare this to my neighbour who has a 2003 G35 sedan. I'm surprised he can see at night. His are really bad, probably due to the angle of the lenses (they run up over the hood so the sun really beats on them). I really wish some of these manufacturers would bring back glass.
IMO, this is just another example of a cheap alternative to glass lenses that went bad.
Exactly. My mother has a 1991 Honda Accord with glass headlights. Clear as the day she bought the car (ok..maybe a few nicks). Compare this to my neighbour who has a 2003 G35 sedan. I'm surprised he can see at night. His are really bad, probably due to the angle of the lenses (they run up over the hood so the sun really beats on them). I really wish some of these manufacturers would bring back glass.
My son had a little Ford Aspire for a while and the headlights constantly required treatment. What I don't understand is that the corner parking/signal lights (also clear plastic or polycarbonate) have always retained their perfect clarity and still look absolutely new, while the headlight lenses (which seem even more important to safe operation) constantly fog and yellow.
Keep in mind that headlight lense's are made from lexan which is not ultraviolent resitant!!! blinker covers are made from Acrylic (sp?) and they don't change much but just fade a little over a long time. On the side that is exposed to the sun most off the day my cars blinker's are a bit more pale orange compaired to the other side!! Acrylic would be too brittel for headlight lense's.
Originally Posted By: Bill888
What I don't understand is that the corner parking/signal lights (also clear plastic or polycarbonate) have always retained their perfect clarity and still look absolutely new, while the headlight lenses (which seem even more important to safe operation) constantly fog and yellow.
Originally Posted By: Bill888
What I don't understand is that the corner parking/signal lights (also clear plastic or polycarbonate) have always retained their perfect clarity and still look absolutely new, while the headlight lenses (which seem even more important to safe operation) constantly fog and yellow.
Kestas
Staff member
I too wish they would bring back glass lamps. The only advantage to modern headlamp designs is styling, and that they are a money maker to the dealer and aftermarket. They certainly don't function better than glass lamps.
Reduction in aerodynamic drag cannot be a good argument since any money you save on gas is eventually spent on new headlight lenses.
I'm surprised the NHSTA doesn't take issue with the fact that the general public safety is compromised with the multitude of foggy lamps on the road and the low visibility to the drivers. After all, they've taken issue with other safety-related items such as tires and TPMS.
Reduction in aerodynamic drag cannot be a good argument since any money you save on gas is eventually spent on new headlight lenses.
I'm surprised the NHSTA doesn't take issue with the fact that the general public safety is compromised with the multitude of foggy lamps on the road and the low visibility to the drivers. After all, they've taken issue with other safety-related items such as tires and TPMS.
It's the UV rays.
When you wax the car, put some wax on the headlights, that will keep them new..
Most people don't think to wax plastic headlamps, but they need protection also.
When you wax the car, put some wax on the headlights, that will keep them new..
Most people don't think to wax plastic headlamps, but they need protection also.
Crystal Vision from Wal-Mart worked great to clear my fogged lenses. Thanks to the Bitog members who gave me the reco.
There are several companies that make a plastic polish. some even specificaly for headlights.
Sand your lights with 2000 or 2500 sandpaper and then rub them out realy good with the plastic/headlight polish.
They will look 80%+ like new.
They will start to yellow over more frequently, but sanding is only needed on the bad headlights.
my 240SX was so bad i was looking to replace the assemblies ($300 ea) then I polished and they look like new.
permatex makes a polishing kit sold in parts stores. OR
http://www.thetoolwarehouse.net/nsearch.aspx?keywords=automotive+headlights
Sand your lights with 2000 or 2500 sandpaper and then rub them out realy good with the plastic/headlight polish.
They will look 80%+ like new.
They will start to yellow over more frequently, but sanding is only needed on the bad headlights.
my 240SX was so bad i was looking to replace the assemblies ($300 ea) then I polished and they look like new.
permatex makes a polishing kit sold in parts stores. OR
http://www.thetoolwarehouse.net/nsearch.aspx?keywords=automotive+headlights
I have always thought that the best thing to do is keep all chemicals away from the lenses. My lenses, 10 years old on one car and 8 years on another are perfectly clear. I only use soap and water on them and keep all waxes and other cleaners away from them. The wifes 2000 Sable (not one of the two above) developed a leak and had condensation on the inside and it failed the safety inspection. It was also fogged on the outside I assume because the contant use of automatic car washes and possibly the previouls owners habits. I replaced the lens with a brand new one and it was no more clear than my factory lenses on my 2002 Sable.
The step daughters Camery had lenses so bad the headlights were almost useless. I used Mequires PlastX on them and got great results. I thought they would be beyond help.
The step daughters Camery had lenses so bad the headlights were almost useless. I used Mequires PlastX on them and got great results. I thought they would be beyond help.
I use plexus plastic cleaner and it works great on the headlights. Unless they are really bad it usually makes them clear
Think for a minute what it would be like to drive without a windshield. Think of all the airborne junk that would hit you in the face. All of that stuff IS hitting your headlights and chips away and deteriorates them.
The comment about UV rays damaging todays typical plastic lexan like lenses is spot on...Of course I bet most people don't know that the halogen bulb itself also contributes to this deterioration as well.
But generally you can wax the lens safely the petrolium evaporates very quickly so does no damage. The UV protection is worth it...look for a wax that specifically states it has UV protection in it.
My 96 Golf has an acrylic lens and after moderate care they are looking almost new....
Another issue is the INSIDE of lamps including the reflector in the inside of the lens...If anything evaporates off say a bulb it will redeposit itself into the reflector and lens all you can do is maybe clean with a damp lightly applied dish detergent sponge attached securely onto a coat hanger.
But generally you can wax the lens safely the petrolium evaporates very quickly so does no damage. The UV protection is worth it...look for a wax that specifically states it has UV protection in it.
My 96 Golf has an acrylic lens and after moderate care they are looking almost new....
Another issue is the INSIDE of lamps including the reflector in the inside of the lens...If anything evaporates off say a bulb it will redeposit itself into the reflector and lens all you can do is maybe clean with a damp lightly applied dish detergent sponge attached securely onto a coat hanger.
I cleaned mine tonight with Crystal View from Walmart. One looks good and one looks like new.
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