\"Headlight\" polishing...

[Don Y]

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]

 

[bitrex]

On 2/21/2023 8:53 PM, Don Y wrote:

On 2/21/2023 6:07 PM, bitrex wrote:
On 2/21/2023 7:32 PM, Don Y wrote:
On 2/21/2023 3:29 PM, Carlos E. R. wrote:

[variations in licensing/registration requirements]

Wow.

What throws many Americans is the notion that they are still
\"in the same country\" and expect laws, requirements, language,
etc. to remain constant (or, at least, consistent!).  And,
it\'s not like there\'s a book/pamphlet to alert you to the
changes you\'d not expect!

[You (spain?) likely are keenly aware when you travel to
another european \"state\" and, likely, aware that the rules
likely change.]

In Boston, you wouldn\'t ask for a \"milkshake\" as that\'s
just \"flavored milk\"; what you really want is a frappe
(with ice cream!).  You\'d buy your liquor at a \"liquor
store\" (where I grew up, it was called a *package* store
or \"packy\" in the vernacular).  And, growing up, the
beer and wine sections of the refrigerated coolers
(need a different license to sell \"spirits\") would
be COVERED at 8:00PM (illegal to sell after 8!).

I think \"frappe\" is pretty out-of-fashion unless one\'s really of the
old New England breed, I don\'t hear it much among people under 50 even
ones who were born here. Nobody\'s going to be confused as to what\'s
being asked for if someone from elsewhere orders a \"milkshake.\"

I\'ve not lived (or *been*) in beantown in 40+ years.  So, my
experiences, there, are admittedly dated.  :

I do recall a pamphlet prepared (tongue-in-cheek) for foreign
students with things like \"traffic lights are only advisory\"...

\"Blinker\" and \"packy\" are still common, though

And rotaries?  Turnpikes?  Parkways?

[Around here, all would be met with blank stares]

Yep, rotaries are still rotaries, but there\'s only one \"turnpike\" and
it\'s called the Mass Pike.

Highways are highways, not \"freeways.\" I don\'t hear \"parkway\" too much.
South Boston is \"Southie\", East Boston is \"Eastie\", Roslindale is
\"Rozzie\", Somerville can be known as \"Sommie\" (uncommon), Cambridge &
Somerville are \"Camberville\" (common).

Jamaica Plain is \"JP\", only a tourist would spell the whole thing out!
Worcester is \"Wuss-tah\", Leominster is \"Lemon-stir\", etc.

I\'ve heard that accents are about 20% your parents and 80% your peer
group so even though my late father was Dorchester-born and raised and
sounded like he was in the Winter Hill gang (though he wouldn\'t have
been at all unhappy to learn that bastard Whitey eventually got what was
coming to him), in the 80s Boston was already becoming a cosmopolitan city.

I was from a working-class family but I went to some better-than-average
public schools where a lot of my classmates were the kids of transplant
doctors and lawyers from California and elsewhere. mainly because my Dad
had lived in the particular town long before it became a hot ticket
real-estate wise.

So my accent is pretty mild in the grand scheme of Boston accents.

 

[bitrex]

On 2/22/2023 2:01 PM, bitrex wrote:

On 2/21/2023 8:53 PM, Don Y wrote:
On 2/21/2023 6:07 PM, bitrex wrote:
On 2/21/2023 7:32 PM, Don Y wrote:
On 2/21/2023 3:29 PM, Carlos E. R. wrote:

[variations in licensing/registration requirements]

Wow.

What throws many Americans is the notion that they are still
\"in the same country\" and expect laws, requirements, language,
etc. to remain constant (or, at least, consistent!).  And,
it\'s not like there\'s a book/pamphlet to alert you to the
changes you\'d not expect!

[You (spain?) likely are keenly aware when you travel to
another european \"state\" and, likely, aware that the rules
likely change.]

In Boston, you wouldn\'t ask for a \"milkshake\" as that\'s
just \"flavored milk\"; what you really want is a frappe
(with ice cream!).  You\'d buy your liquor at a \"liquor
store\" (where I grew up, it was called a *package* store
or \"packy\" in the vernacular).  And, growing up, the
beer and wine sections of the refrigerated coolers
(need a different license to sell \"spirits\") would
be COVERED at 8:00PM (illegal to sell after 8!).

I think \"frappe\" is pretty out-of-fashion unless one\'s really of the
old New England breed, I don\'t hear it much among people under 50
even ones who were born here. Nobody\'s going to be confused as to
what\'s being asked for if someone from elsewhere orders a \"milkshake.\"

I\'ve not lived (or *been*) in beantown in 40+ years.  So, my
experiences, there, are admittedly dated.  :

I do recall a pamphlet prepared (tongue-in-cheek) for foreign
students with things like \"traffic lights are only advisory\"...

\"Blinker\" and \"packy\" are still common, though

And rotaries?  Turnpikes?  Parkways?

[Around here, all would be met with blank stares]



Yep, rotaries are still rotaries, but there\'s only one \"turnpike\" and
it\'s called the Mass Pike.

Highways are highways, not \"freeways.\" I don\'t hear \"parkway\" too much.
South Boston is \"Southie\", East Boston is \"Eastie\", Roslindale is
\"Rozzie\", Somerville can be known as \"Sommie\" (uncommon), Cambridge &
Somerville are \"Camberville\" (common).

Jamaica Plain is \"JP\", only a tourist would spell the whole thing out!
Worcester is \"Wuss-tah\", Leominster is \"Lemon-stir\", etc.

I\'ve heard that accents are about 20% your parents and 80% your peer
group so even though my late father was Dorchester-born and raised and
sounded like he was in the Winter Hill gang (though he wouldn\'t have
been at all unhappy to learn that bastard Whitey eventually got what was
coming to him), in the 80s Boston was already becoming a cosmopolitan city.

I was from a working-class family but I went to some better-than-average
public schools where a lot of my classmates were the kids of transplant
doctors and lawyers from California and elsewhere. mainly because my Dad
had lived in the particular town long before it became a hot ticket
real-estate wise.

So my accent is pretty mild in the grand scheme of Boston accents.

I guess the proper name of the road is the \"Jamaica Parkway\" but in
practice it\'s just called the Jamaicaway:

https://en.wikipedia.org/wiki/Jamaicaway

 

[Don Y]

On 2/22/2023 12:01 PM, bitrex wrote:

Yep, rotaries are still rotaries, but there\'s only one \"turnpike\" and it\'s
called the Mass Pike.

Highways are highways, not \"freeways.\" I don\'t hear \"parkway\" too much.

Alewife-Brook? Lynn Fells? Fresh Pond? Furnace Brook? Revere Beach?
Mystic Valley? VFW? West Roxbury? Blue Hills? (I can\'t remember any
others but suspect that\'s a limitation of my memory and not an accurate
reflection of reality)

South
Boston is \"Southie\", East Boston is \"Eastie\", Roslindale is \"Rozzie\",
Somerville can be known as \"Sommie\" (uncommon), Cambridge & Somerville are
\"Camberville\" (common).

Plus all of the -port variants.

Jamaica Plain is \"JP\", only a tourist would spell the whole thing out!
Worcester is \"Wuss-tah\", Leominster is \"Lemon-stir\", etc.

Billerica as bill-ricka. Medford as medfuh.

I\'ve heard that accents are about 20% your parents and 80% your peer group so
even though my late father was Dorchester-born and raised and sounded like he
was in the Winter Hill gang (though he wouldn\'t have been at all unhappy to
learn that bastard Whitey eventually got what was coming to him), in the 80s
Boston was already becoming a cosmopolitan city.

Yes, language and accents tend to melt, over time.
I have a very distinctive accent that can pinpoint
me to *a* town -- and none of the towns around it!
But, it takes an ear with a similar inclination to detect.
(I\'ve encountered people, here, 2000 miles away and
been able to ask them, out of the blue, if they had
similar origins: \"Yeah.\" They don\'t even wonder
how I knew -- sort of like Brooklyn)

I was from a working-class family but I went to some better-than-average public
schools where a lot of my classmates were the kids of transplant doctors and
lawyers from California and elsewhere. mainly because my Dad had lived in the
particular town long before it became a hot ticket real-estate wise.

So my accent is pretty mild in the grand scheme of Boston accents.

I find the vocabulary to be more telling. People just don\'t use
certain words elsewhere. \"Packy\" raises eyebrows among most of
the people I\'ve encountered since leaving New England -- yet,
it seems so natural to me that I don\'t even realize I\'m saying it.
Or rotaries, frappes, grinders, etc.

 

[bitrex]

On 2/22/2023 6:30 PM, Don Y wrote:

On 2/22/2023 12:01 PM, bitrex wrote:
Yep, rotaries are still rotaries, but there\'s only one \"turnpike\" and
it\'s called the Mass Pike.

Highways are highways, not \"freeways.\" I don\'t hear \"parkway\" too much.

Alewife-Brook? Lynn Fells?  Fresh Pond?  Furnace Brook?  Revere Beach?
Mystic Valley?  VFW?  West Roxbury?  Blue Hills?  (I can\'t remember any
others but suspect that\'s a limitation of my memory and not an accurate
reflection of reality)

Yah there are all those. I haven\'t lived close enough to the city in
years for them to come up in conversation regularly, though.

I find the vocabulary to be more telling.  People just don\'t use
certain words elsewhere.  \"Packy\" raises eyebrows among most of
the people I\'ve encountered since leaving New England -- yet,
it seems so natural to me that I don\'t even realize I\'m saying it.
Or rotaries, frappes, grinders, etc.

Seems it\'s sometimes considered a slur in the UK and some Commonwealth
countries, like what someone would call a convenience store run by a
Pakistani. Obviously doesn\'t have that connotation in New England

 

[John Miles, KE5FX]

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.

It\'s counterproductive, of course, because the car ends up being replaced
by a newly-manufactured one that much earlier. But the bureaucrats
have no incentive to get their heads on straight, and the automakers
have even less incentive to object.

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.

-- john, KE5FX

 

[Don Y]

On 2/22/2023 4:43 PM, bitrex wrote:

On 2/22/2023 6:30 PM, Don Y wrote:
On 2/22/2023 12:01 PM, bitrex wrote:
Yep, rotaries are still rotaries, but there\'s only one \"turnpike\" and it\'s
called the Mass Pike.

Highways are highways, not \"freeways.\" I don\'t hear \"parkway\" too much.

Alewife-Brook? Lynn Fells?  Fresh Pond?  Furnace Brook?  Revere Beach?
Mystic Valley?  VFW?  West Roxbury?  Blue Hills?  (I can\'t remember any
others but suspect that\'s a limitation of my memory and not an accurate
reflection of reality)

Yah there are all those. I haven\'t lived close enough to the city in years for
them to come up in conversation regularly, though.

Chances are, you\'d talk about *places* that were recognizable and
not the (full) names of the roads on which they reside: Joyce
Chen\'s on Fresh Pond (aka BIG Joyce Chen\'s).

In chitown, LSD isn\'t a recreational drug.

I find the vocabulary to be more telling.  People just don\'t use
certain words elsewhere.  \"Packy\" raises eyebrows among most of
the people I\'ve encountered since leaving New England -- yet,
it seems so natural to me that I don\'t even realize I\'m saying it.
Or rotaries, frappes, grinders, etc.

Seems it\'s sometimes considered a slur in the UK and some Commonwealth
countries, like what someone would call a convenience store run by a Pakistani.

Huh? Oh, I see. Never would have occurred to me as it\'s
\"true\" meaning is so ingrained.

> Obviously doesn\'t have that connotation in New England

 

[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.

So, it\'s not abrasion that is the source of the problem...

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.

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?)

In defiance of \"regulations\", are there better products that
an owner could self-apply? Or, is this just a matter of degrees...
you\'re going to have a problem, it\'s just a question of sooner vs. later?

It\'s counterproductive, of course, because the car ends up being replaced
by a newly-manufactured one that much earlier. But the bureaucrats
have no incentive to get their heads on straight, and the automakers
have even less incentive to object.

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

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?

 

[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)?

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

 

[Lasse Langwadt Christensen]

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

 

[John Miles, KE5FX]

On Monday, February 20, 2023 at 11:45:55 AM UTC-8, Don Y wrote:

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.
So, it\'s not abrasion that is the source of the problem...

Not from what I\'ve seen.

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.

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.

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...

> 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.

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.

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.

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

-- john, KE5FX

 

[Liz Tuddenham]

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.


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

 

[Carlos E. R.]

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?

--
Cheers,
Carlos E.R.

 

[Carl]

On 2/20/23 14:48, Don Y wrote:

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)?

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

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

--
Regards,
Carl

 

[Don Y]

On 2/20/2023 1:31 PM, 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

(stupid question) Why do you have to REMOVE the existing coating
before \"augmenting\" the sealant?

years ago, it has completely failed already. Ordinary metal polish
seems to clean the surface clouding,

A quick search suggests toothpaste, vinegar, etc. So, maybe (?)
removing the haze is relatively easy but preventing its appearance
(or recurrence) is the bigger issue?

If the retreated lenses lasted \"2 years\", how long would they
have lasted *without* that treatment?

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.

 

[Don Y]

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.)

 

[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?

 

[Liz Tuddenham]

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.


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

 

[Carlos E. R.]

On 2023-02-20 22:30, 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.

If it is UV from the sun, then there should be a sacrificial coating
that filters UV. Polish away and replace. IMHO.

--
Cheers,
Carlos E.R.

 

[Lasse Langwadt Christensen]

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

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