\"Headlight\" polishing...

[Martin Rid]

Don Y <blockedofcourse@foo.invalid> Wrote in message:r
> On 2/20/2023 2:00 PM, Carlos E. R. wrote:> On 2023-02-20 21:31, Liz Tuddenham wrote:>> Don Y <blockedofcourse@foo.invalid> wrote:>>>> [...]>>> That suggests that any polishing operations likely further remove>>> the coating, thus accelerating a recurrence? (Or, do commercial>>> products targeting this application include a followup \"resealing\">>> operation -- presumably, with a BETTER protectant than the original?)>>>> I used a (quite expensive) commercial remover and re-coater about 2>> years ago, it has completely failed already. Ordinary metal polish>> seems to clean the surface clouding, and I am now looking for a cheap>> clear varnish that will block UV and is easy to remove when necessary.>> Unfortunately most outdoor varnishes seem to contain polyurethane which>> is difficult to remove when it starts to break down and peel off.> > I\'m curious.> > Block UV from the lamp, or from the sun? And why?Wow, I hadn\'t thought that the \"emitter\" would be a significant UV source.But, I guess headlamps nowadays are of differing technologies (HID,LED, etc.)

On the road pollution plays a part. Maybe nox or the resulting
cat emissions. If the car/truck sits idle the headlights take
forever to haze up.

Cheers
--


----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html

 

[Don Y]

On 2/20/2023 1:23 PM, John Miles, KE5FX wrote:

That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence? (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

That\'s what some people have been doing -- aggressively polishing off the
old coating and replacing it with either paint protection film or a different
polish. Sometimes both.

But, proactively? I.e., BEFORE the clouding occurs (so they are just
removing a \"clear\" film?

In defiance of \"regulations\", are there better products that
an owner could self-apply?

I imagine so, but fortunately haven\'t had to deal with it myself.

Ditto. I\'m more interested in avoiding the problem in \"material
selection\". The car manufacturers likely knew the long term effects
of exposure on the material and decided it was a worthwhile tradeoff
(in THEIR minds). I would be curious to see what other materials
they considered and why they opted against them (given that headlamps
likely have more concerns than just \"transparency\")

In the EU it will be harder to get the good stuff. Some people are saying
they can\'t even order 60/40 solder as individual customers anymore...

Well, it\'s a different sort of place, apparently! :>

I\'ve not seen any problems with solder or even many of the \"cleaners\"
that likely will eventually see a ban (if only for propellant).

Because the cost of the headlamps (plus labor) is so outrageous?

Yes; even commodity-level cars have four-figure headlight assemblies these
days. The sooner the car isn\'t worth saving, the sooner somebody will have to
buy a new one.

Yikes! I\'d seen figures like $400 for taillight assy\'s which made
much of the silly extravagance in their designs foolhardy.

Right now the average age of passenger cars on US roads is apparently over
12 years and still climbing. This is obviously unsustainable for the car
companies.

Likely also has economic ramifications for places where cars are
taxed (\"registration\") as property and not at a fixed rate.

Caveat: this is largely just speculation with regard to headlight coatings
and sealants, but indisputable in other areas. See, e.g.:
http://www.pedrosgarage.com/site-5/warped.html . It will cost you
thousands of dollars to fix this if you do it the factory-sanctioned way.
Yikes! There must be a good aftermarket for replacement OEM-ish
panels!? Or, is this anathema to the \"all original\" mentality?

That\'s what Pedro does... you send him your door skins and $500, and
he fixes them with the correct adhesive. This is a bargain compared to
paying up to several thousand dollars at the dealer depending on optional
trim.

So, part of his pitch is that your vehicle remains \"all original\".

Havent had to deal with this personally either, knock on wood. My car is
10 years old but it has an easy life.

I had to repair the headliner in mine, some years ago. But, I\'m
planning on redoing the entire interior without regard for
provenance; it\'s a *car*, not an *investment*! :> YMMV, of course.

 

[Jasen Betts]

On 2023-02-20, Don Y <blockedofcourse@foo.invalid> wrote:

Does the \"fog\" that plagues modern headlights come as
a result of UV damage? Or, fine-particle abrasion
(the lights being on the leading edge of the vehicle)?

Mostly UV i think

Given that forming large \"oddly shaped\" objects out of
glass is costly (or so my glass-guy tells me!), are
there other transparent materials that could be used?

Polycarbonate, acrylic etc

> [If so, why didn\'t car manufacturers use it/them?]

They do. exspecially in places outside the control of
US government.

And, in the event of polycarbonate being the only
practical, \"moldable\" solution, how can I define
constraints on the shape to ensure it can be
\"reasonably\" polished when/if such damage occurs?
(assuming I\'m not keen on replacement)

English doesn\'t work?

The more you write the less I understand. Obviously
I\'m communicating with Don Y.


--
Jasen.
pǝsɹǝʌǝɹ sʇɥƃᴉɹ ll∀

 

[Jasen Betts]

On 2023-02-20, Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

Don Y <blockedofcourse@foo.invalid> wrote:

[...]
That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence? (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

I used a (quite expensive) commercial remover and re-coater about 2
years ago, it has completely failed already. Ordinary metal polish
seems to clean the surface clouding, and I am now looking for a cheap
clear varnish that will block UV and is easy to remove when necessary.
Unfortunately most outdoor varnishes seem to contain polyurethane which
is difficult to remove when it starts to break down and peel off.

Perhaps acrylic lacquer (Automotive clearcoat)

apparently you can get 2K in a spray can - there must be some fancy
plumbing involved there.

--
Jasen.
pǝsɹǝʌǝɹ sʇɥƃᴉɹ ll∀

 

[Carlos E.R.]

On 2023-02-20 22:26, Don Y wrote:

On 2/20/2023 2:00 PM, Carlos E. R. wrote:
On 2023-02-20 21:31, Liz Tuddenham wrote:
Don Y <blockedofcourse@foo.invalid> wrote:

[...]
That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence?  (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

I used a (quite expensive) commercial remover and re-coater about 2
years ago, it has completely failed already.  Ordinary metal polish
seems to clean the surface clouding, and I am now looking for a cheap
clear varnish that will block UV and is easy to remove when necessary.
Unfortunately most outdoor varnishes seem to contain polyurethane which
is difficult to remove when it starts to break down and peel off.

I\'m curious.

Block UV from the lamp, or from the sun? And why?

Wow, I hadn\'t thought that the \"emitter\" would be a significant UV source.
But, I guess headlamps nowadays are of differing technologies (HID,
LED, etc.)

I don\'t know if internal UV is significant. I was asking


One of the technologies for white LED is to emit UV and transform to
visible with a fluorescent layer - same as mercury vapor fluorescent lights.

I don\'t think halogen emits much UV. Rather IR.

--
Cheers, Carlos.

 

[John Larkin]

On Mon, 20 Feb 2023 11:30:29 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

Does the \"fog\" that plagues modern headlights come as
a result of UV damage? Or, fine-particle abrasion
(the lights being on the leading edge of the vehicle)?

Given that forming large \"oddly shaped\" objects out of
glass is costly (or so my glass-guy tells me!), are
there other transparent materials that could be used?

Beer bottles are cheap.

 

[Lasse Langwadt Christensen]

tirsdag den 21. februar 2023 kl. 02.06.24 UTC+1 skrev Carlos E.R.:

On 2023-02-20 22:26, Don Y wrote:
On 2/20/2023 2:00 PM, Carlos E. R. wrote:
On 2023-02-20 21:31, Liz Tuddenham wrote:
Don Y <blocked...@foo.invalid> wrote:

[...]
That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence? (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

I used a (quite expensive) commercial remover and re-coater about 2
years ago, it has completely failed already. Ordinary metal polish
seems to clean the surface clouding, and I am now looking for a cheap
clear varnish that will block UV and is easy to remove when necessary.
Unfortunately most outdoor varnishes seem to contain polyurethane which
is difficult to remove when it starts to break down and peel off.

I\'m curious.

Block UV from the lamp, or from the sun? And why?

Wow, I hadn\'t thought that the \"emitter\" would be a significant UV source.
But, I guess headlamps nowadays are of differing technologies (HID,
LED, etc.)
I don\'t know if internal UV is significant. I was asking


One of the technologies for white LED is to emit UV and transform to
visible with a fluorescent layer - same as mercury vapor fluorescent lights.

https://youtu.be/7fRjMHtnShs

 

[Don Y]

On 2/20/2023 5:43 PM, Jasen Betts wrote:

[If so, why didn\'t car manufacturers use it/them?]

They do. exspecially in places outside the control of
US government.

We\'ve already seen comments that the EU has materials
constraints...

And, in the event of polycarbonate being the only
practical, \"moldable\" solution, how can I define
constraints on the shape to ensure it can be
\"reasonably\" polished when/if such damage occurs?
(assuming I\'m not keen on replacement)

English doesn\'t work?

What *units* to express this. Just saying \"don\'t make
it too curvy\" is hardly a specification, eh?

The more you write the less I understand. Obviously
I\'m communicating with Don Y.

 

[Don Y]

On 2/20/2023 5:16 PM, Martin Rid wrote:

On the road pollution plays a part. Maybe nox or the resulting
cat emissions. If the car/truck sits idle the headlights take
forever to haze up.

Possible. OTOH, a neighbor has some uplight landscape lights
that are almost opaque, from \"age\". No idea as to what the
material is nor how long they\'ve been staring at the sun.

OToOH, the \"acrylic\"? lenses in our lights are still crystal
clear -- but, they look outward instead of upward (?) and
can be of an entirely different composition.

[Materials Science seems to be a stumbling block for me...]

 

[Don Y]

On 2/20/2023 2:30 PM, Liz Tuddenham wrote:

Carlos E. R. <robin_listas@es.invalid> wrote:

On 2023-02-20 21:31, Liz Tuddenham wrote:
Don Y <blockedofcourse@foo.invalid> wrote:

[...]
That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence? (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

I used a (quite expensive) commercial remover and re-coater about 2
years ago, it has completely failed already. Ordinary metal polish
seems to clean the surface clouding, and I am now looking for a cheap
clear varnish that will block UV and is easy to remove when necessary.
Unfortunately most outdoor varnishes seem to contain polyurethane which
is difficult to remove when it starts to break down and peel off.

I\'m curious.

Block UV from the lamp, or from the sun? And why?

As far as I can tell, the polycarbonate lens is affected by UV from the
sun (and the sky in general) and reacts by going milky. A coating is
applied to the outside to block external UV, but, as you point out,
there is also UV emitted by halogen bulbs that may affect the inside
(perhapes depending on the wavelength)..

I don\'t know whether the UV penetrates the thickness of the
polycarbonate and damages it right through, or whether it only affects
the surface which can be taken off with fine abrasive from time to time.

Or, is the protective coating the material that is clouding?

 

[Don Y]

On 2/20/2023 3:00 PM, Lasse Langwadt Christensen wrote:

mandag den 20. februar 2023 kl. 22.28.46 UTC+1 skrev Don Y:
On 2/20/2023 1:22 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 20.48.20 UTC+1 skrev Don Y:
On 2/20/2023 12:08 PM, John Miles, KE5FX wrote:
On Monday, February 20, 2023 at 10:33:53 AM UTC-8, Don Y wrote:
Does the \"fog\" that plagues modern headlights come as
a result of UV damage?

Sort of. What seems to happen with European cars in particular
is that the anti-UV coating on the headlights is either made from
\"environmentally friendly\" materials mandated by the EU, or adhered
to the glass with them. The resuilt is essentially equivalent to
planned obsolescence, where the clock starts in the factory before
the car is even built.
An afterthought:

Is the damage entirely superficial? Or, does it permeate the
\"lens\" (to varying degrees)?

over time it goes deeper until it can\'t be fixed

I.e., could just a chemical \"solvent/reagent\" application
reverse the process? Or, must the damaged material be
mechanically removed (i.e., buffed off)?

you have to sand off the coating and the damaged polycarbonate,
polish and coat with new protection
So, the commercial products are really just used to cleanly
remove material, not restore it?

the kits I\'ve seen are a set of different grit sandpaper, some polish and a sealer/protector

Sandpaper seems really aggressive, regardless of the fineness of grit.
I\'d have thought it was just \"vigorous rubbing\" with a soft pad
that was removing the material (motorized to expedite the operation).

Wouldn\'t the sandpaper leave fine scratches in the material?

you can get coatings that claim to prevent the problem, but I have no idea if they really work
https://www.amazon.com/gp/product/B01M4RVVX6

Which begs the question, \"Why don\'t car manufacturers use it?\"

 

[Don Y]

On 2/20/2023 2:00 PM, Carl wrote:

The damage is apparently oxidation at the surface that slowly works it\'s way
in.  I\'ve never done it but I\'ve watched several YouTube videos so I\'m
obviously an expert -)).

Ah! Well, given that it\'s been *several*... :>

The best treatment seems to be mechanical
polishing.  Some recommend using toothpaste on a sponge or cloth, and some
start there and work up to very tiny grits with a drill-driven polishing pad.

I wonder if feldspar or faultless starch would be too benign?

Chemical polishing is also recommended, mostly using DEET as found in Deep
Woods Off Mosquito Repellent.

!! ?

Spray on, polish off with a soft cloth.  Fast
and easy, especially for highly curved surfaces, but some say it doesn\'t work

---------------------------^^^^^^^^^^^^^^^^^^^^^^ this being what I\'m
interested in. E.g., you can buff out the bodywork of a car with a 5\" pad
on a drill/rotary sander -- because none of the surfaces have significant
curvature. But, if you were trying to deal with fine detail, it would
seem like you\'d be stuck with a fine brush and lots of diligent
observation.

[You\'ll note that light assemblies tend to be large *smooth* surfaces without
much detail or changes in \"sign\" of curvature]

as well and doesn\'t last as long.  My guess is that it doesn\'t remove as much
oxidation so a film of damaged material is left behind, but it does melt and
flow the surface to at least partially heal scratches.

So, it\'s trying to modify the substance instead of removing it.

Again, I\'ve never done
this, just watched videos.

I suppose I should just start accumulating different materials
and doing accelerated exposure with different polishing remedies.

Or, treat it as an FRU and design for ease of replacement.
(the actual material is dirt cheap -- *if* it can be readily
isolated as a standalone component)

Glass is just so much less of a hassle...

 

[Dean Hoffman]

On Monday, February 20, 2023 at 12:33:53 PM UTC-6, Don Y wrote:

Does the \"fog\" that plagues modern headlights come as
a result of UV damage? Or, fine-particle abrasion
(the lights being on the leading edge of the vehicle)?

Given that forming large \"oddly shaped\" objects out of
glass is costly (or so my glass-guy tells me!), are
there other transparent materials that could be used?

[If so, why didn\'t car manufacturers use it/them?]

And, in the event of polycarbonate being the only
practical, \"moldable\" solution, how can I define
constraints on the shape to ensure it can be
\"reasonably\" polished when/if such damage occurs?
(assuming I\'m not keen on replacement)

[E.g., a purely convex surface would be easier to
polish than one that arbitrarily mixes concave and
convex; though, even there, too high a degree of
curvature could prove difficult to manage]

In the good old days, there were cars that had \"eyelids\" that closed when the headlights weren\'t in use.

 

[Lasse Langwadt Christensen]

tirsdag den 21. februar 2023 kl. 03.09.27 UTC+1 skrev Don Y:

On 2/20/2023 3:00 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 22.28.46 UTC+1 skrev Don Y:
On 2/20/2023 1:22 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 20.48.20 UTC+1 skrev Don Y:
On 2/20/2023 12:08 PM, John Miles, KE5FX wrote:
On Monday, February 20, 2023 at 10:33:53 AM UTC-8, Don Y wrote:
Does the \"fog\" that plagues modern headlights come as
a result of UV damage?

Sort of. What seems to happen with European cars in particular
is that the anti-UV coating on the headlights is either made from
\"environmentally friendly\" materials mandated by the EU, or adhered
to the glass with them. The resuilt is essentially equivalent to
planned obsolescence, where the clock starts in the factory before
the car is even built.
An afterthought:

Is the damage entirely superficial? Or, does it permeate the
\"lens\" (to varying degrees)?

over time it goes deeper until it can\'t be fixed

I.e., could just a chemical \"solvent/reagent\" application
reverse the process? Or, must the damaged material be
mechanically removed (i.e., buffed off)?

you have to sand off the coating and the damaged polycarbonate,
polish and coat with new protection
So, the commercial products are really just used to cleanly
remove material, not restore it?

the kits I\'ve seen are a set of different grit sandpaper, some polish and a sealer/protector
Sandpaper seems really aggressive, regardless of the fineness of grit.
I\'d have thought it was just \"vigorous rubbing\" with a soft pad
that was removing the material (motorized to expedite the operation).

Wouldn\'t the sandpaper leave fine scratches in the material?

that\'s why you need multiple grits, you start with the coarsest to remove material and
then each finer grit removes the scratches from the previous grit. Sanding 101

you can get coatings that claim to prevent the problem, but I have no idea if they really work
https://www.amazon.com/gp/product/B01M4RVVX6
Which begs the question, \"Why don\'t car manufacturers use it?\"

they do, the bottle says lasts for a a year...

 

[Lasse Langwadt Christensen]

tirsdag den 21. februar 2023 kl. 03.26.19 UTC+1 skrev Dean Hoffman:

On Monday, February 20, 2023 at 12:33:53 PM UTC-6, Don Y wrote:
Does the \"fog\" that plagues modern headlights come as
a result of UV damage? Or, fine-particle abrasion
(the lights being on the leading edge of the vehicle)?

Given that forming large \"oddly shaped\" objects out of
glass is costly (or so my glass-guy tells me!), are
there other transparent materials that could be used?

[If so, why didn\'t car manufacturers use it/them?]

And, in the event of polycarbonate being the only
practical, \"moldable\" solution, how can I define
constraints on the shape to ensure it can be
\"reasonably\" polished when/if such damage occurs?
(assuming I\'m not keen on replacement)

[E.g., a purely convex surface would be easier to
polish than one that arbitrarily mixes concave and
convex; though, even there, too high a degree of
curvature could prove difficult to manage]

In the good old days, there were cars that had \"eyelids\" that closed when the headlights weren\'t in use.

that was to hide the ugly headlights the rules forced them to use in the US, the choice was round or square
sealed beam

 

[Don Y]

On 2/20/2023 7:43 PM, Lasse Langwadt Christensen wrote:

tirsdag den 21. februar 2023 kl. 03.09.27 UTC+1 skrev Don Y:
On 2/20/2023 3:00 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 22.28.46 UTC+1 skrev Don Y:
On 2/20/2023 1:22 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 20.48.20 UTC+1 skrev Don Y:
On 2/20/2023 12:08 PM, John Miles, KE5FX wrote:
On Monday, February 20, 2023 at 10:33:53 AM UTC-8, Don Y wrote:
Does the \"fog\" that plagues modern headlights come as
a result of UV damage?

Sort of. What seems to happen with European cars in particular
is that the anti-UV coating on the headlights is either made from
\"environmentally friendly\" materials mandated by the EU, or adhered
to the glass with them. The resuilt is essentially equivalent to
planned obsolescence, where the clock starts in the factory before
the car is even built.
An afterthought:

Is the damage entirely superficial? Or, does it permeate the
\"lens\" (to varying degrees)?

over time it goes deeper until it can\'t be fixed

I.e., could just a chemical \"solvent/reagent\" application
reverse the process? Or, must the damaged material be
mechanically removed (i.e., buffed off)?

you have to sand off the coating and the damaged polycarbonate,
polish and coat with new protection
So, the commercial products are really just used to cleanly
remove material, not restore it?

the kits I\'ve seen are a set of different grit sandpaper, some polish and a sealer/protector
Sandpaper seems really aggressive, regardless of the fineness of grit.
I\'d have thought it was just \"vigorous rubbing\" with a soft pad
that was removing the material (motorized to expedite the operation).

Wouldn\'t the sandpaper leave fine scratches in the material?

that\'s why you need multiple grits, you start with the coarsest to remove material and
then each finer grit removes the scratches from the previous grit. Sanding 101

I would still think that would leave scratches -- albeit very fine
ones. These wouldn\'t be present if a \"buffing wheel\" was used
(with a lubricating agent).

you can get coatings that claim to prevent the problem, but I have no idea if they really work
https://www.amazon.com/gp/product/B01M4RVVX6
Which begs the question, \"Why don\'t car manufacturers use it?\"

they do, the bottle says lasts for a a year...

 

[Don Y]

On 2/20/2023 5:16 PM, Martin Rid wrote:

On the road pollution plays a part. Maybe nox or the resulting
cat emissions. If the car/truck sits idle the headlights take
forever to haze up.

Does the same sort of thing happen to TAIL lights? I would
assume they are made of similar material (?).

I will have to walk through the parking lot, next time I\'m out
shopping, to see if I can find a vehicle with \"bad headlights\"
and check its tail lights!

 

[Liz Tuddenham]

Carlos E.R. <robin_listas@es.invalid> wrote:

[...]
> I don\'t think halogen emits much UV. Rather IR.

They emit a lot of IR but they also emit a significant amount of UV.

I found the beam pattern of a halogen foglight at a distance of about
500mm was the same shape and size as a recumbent piglet, so I designed a
piglet incubator using 24v lorry foglights. After a while we found that
the piglets were getting sunburnt, so we had to fit UV filters to the
foglights.

These lamps were probably only emitting long-wavelength UV; damage to
plastics is more likely to be caused by short-wavelength UV found in
sunlight.

--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[Liz Tuddenham]

Don Y <blockedofcourse@foo.invalid> wrote:

On 2/20/2023 2:30 PM, Liz Tuddenham wrote:
Carlos E. R. <robin_listas@es.invalid> wrote:

On 2023-02-20 21:31, Liz Tuddenham wrote:
Don Y <blockedofcourse@foo.invalid> wrote:

[...]
That suggests that any polishing operations likely further remove
the coating, thus accelerating a recurrence? (Or, do commercial
products targeting this application include a followup \"resealing\"
operation -- presumably, with a BETTER protectant than the original?)

I used a (quite expensive) commercial remover and re-coater about 2
years ago, it has completely failed already. Ordinary metal polish
seems to clean the surface clouding, and I am now looking for a cheap
clear varnish that will block UV and is easy to remove when necessary.
Unfortunately most outdoor varnishes seem to contain polyurethane which
is difficult to remove when it starts to break down and peel off.

I\'m curious.

Block UV from the lamp, or from the sun? And why?

As far as I can tell, the polycarbonate lens is affected by UV from the
sun (and the sky in general) and reacts by going milky. A coating is
applied to the outside to block external UV, but, as you point out,
there is also UV emitted by halogen bulbs that may affect the inside
(perhapes depending on the wavelength)..

I don\'t know whether the UV penetrates the thickness of the
polycarbonate and damages it right through, or whether it only affects
the surface which can be taken off with fine abrasive from time to time.

Or, is the protective coating the material that is clouding?

I think that is the first thing that happens, then the lens starts to go
cloudy too. The \'rejuvenator\' works mainly by stripping and replacing
the coating. It contains some unusual-smelling solvents which give the
impression of being quite toxic.


--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk

 

[Liz Tuddenham]

Don Y <blockedofcourse@foo.invalid> wrote:

On 2/20/2023 7:43 PM, Lasse Langwadt Christensen wrote:
tirsdag den 21. februar 2023 kl. 03.09.27 UTC+1 skrev Don Y:
On 2/20/2023 3:00 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 22.28.46 UTC+1 skrev Don Y:
On 2/20/2023 1:22 PM, Lasse Langwadt Christensen wrote:
mandag den 20. februar 2023 kl. 20.48.20 UTC+1 skrev Don Y:
On 2/20/2023 12:08 PM, John Miles, KE5FX wrote:
On Monday, February 20, 2023 at 10:33:53 AM UTC-8, Don Y wrote:
Does the \"fog\" that plagues modern headlights come as
a result of UV damage?

Sort of. What seems to happen with European cars in particular
is that the anti-UV coating on the headlights is either made from
\"environmentally friendly\" materials mandated by the EU, or adhered
to the glass with them. The resuilt is essentially equivalent to
planned obsolescence, where the clock starts in the factory before
the car is even built.
An afterthought:

Is the damage entirely superficial? Or, does it permeate the
\"lens\" (to varying degrees)?

over time it goes deeper until it can\'t be fixed

I.e., could just a chemical \"solvent/reagent\" application
reverse the process? Or, must the damaged material be
mechanically removed (i.e., buffed off)?

you have to sand off the coating and the damaged polycarbonate,
polish and coat with new protection
So, the commercial products are really just used to cleanly
remove material, not restore it?

the kits I\'ve seen are a set of different grit sandpaper, some polish
and a sealer/protector Sandpaper seems really aggressive, regardless of
the fineness of grit. I\'d have thought it was just \"vigorous rubbing\"
with a soft pad that was removing the material (motorized to expedite
the operation).

Wouldn\'t the sandpaper leave fine scratches in the material?

that\'s why you need multiple grits, you start with the coarsest to
thremove material and en each finer grit removes the scratches from the
thprevious grit. Sanding 101

I would still think that would leave scratches -- albeit very fine
ones. These wouldn\'t be present if a \"buffing wheel\" was used
(with a lubricating agent).

The kits contain a re-coating varnish which has a similar refrective
index to the lens material. This fills in any small residual scratches.

you can get coatings that claim to prevent the problem, but I have no
idea if they really work > https://www.amazon.com/gp/product/B01M4RVVX6
Which begs the question, \"Why don\'t car manufacturers use it?\"

they do, the bottle says lasts for a a year...

After two years mine was so bad it got an \'advisory\' warning at the MOT
test. If this is going to be an annual job, it will be a non-trivial
addition to the running expenses.

On a previous car I found the beam pattern of the headlights was so bad
it dazzled oncoming drivers, and didn\'t illuminate the roadside verge.
Oncoming drivers kept flashing their headlights at me, even though mine
were on dipped beam and adjusted according to the manufacturer\'s
instructions. I used to dread the slightest trace of fog because there
were shafts of light projecting upwards immediately in front of the
bonnet that lit up a dazzling curtain and blocked my view of the road.

In desperation I scrapped the fancy styled headlights and replaced them
with a black-painted rectangle of aluminium with a circular hole in the
middle. Then I fitted a pair of ordinary 7-inch round halogen
headlights with glass lenses. There were a few raised eyebrows from the
MOT tester, but the beam pattern was correct, so he issued a \'pass\'
certificate.

The modification transformed night driving and, of course, there were no
ageing problems with the glass lenses.


--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk