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Old 11th December 2015, 14:00   #11
klarzy
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when remocing deeper pits and scratches (upto 0.5mm deep) then you need to remove that as a uniform layer across the whole light to prevent lensing.
This of course removes a thin gel like coating which can burn and build up on the lens if you have the abrasive moving too fast.

A good finishing compound like £m headlight poish and protect will leave some protection in the fine surface, but a sprayed on clear coat alowed to go very hard before fitting may be the best long term protection...

i am experimenting with that now...
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Old 11th December 2015, 22:34   #12
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As there have been some interesting points on this thread I have added a link to this into the How To
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Old 11th December 2015, 23:14   #13
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Are we missing the point?

My understanding is that QH bulbs generate excessive UV which is usually filtered out by the glass housing. These days the housings are not glass and I doubt whether the 'plastic' (may be the wrong term for polycarbonate) filters it out. Hence the UV protection.

I was buying MR11 QH lamps for a fibre-optic decoration a year ago and the spec. included 'UV stop' or something similar. The MR11 includes a reflector but these didn't have have a glass on the front so obviously no filter. The seller sent some with the glass front but I haven't worked out a simple method to check that the filter works. Any ideas?

Have a look at this link, particularly the the paragraph titled Spectrum.

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

If you haven't got the QH headlamps then I wouldn't bother about the UV protection, but if you have then think about the other drivers' eyes.

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Old 12th December 2015, 09:37   #14
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Originally Posted by 75 tinkerer View Post
My understanding is that QH bulbs generate excessive UV which is usually filtered out by the glass housing.
The 'housing' is the envelope containing the filament. They use a 'hard' gass to minimise UV emission.

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These days the housings are not glass and I doubt whether the 'plastic' (may be the wrong term for polycarbonate) filters it out. Hence the UV protection.
The headlamp front cover (referred to as the 'lens') is made of polycarbonate. As noted earlier, this material is degraded by UV. However, it's UV from sunlight that does this. The UV emitted by QH bulbs is comparatively weak. The UV protectant in headlamp lenses degrades on the outside rather than the inside.

Quote:
Have a look at this link, particularly the the paragraph titled Spectrum.
According to this, the UV emitted is relatively high wavelength 'near UV' which isn't particularly active. The greatest proportion of the emission spectrum is the Infra Red (heat).

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Old 15th December 2015, 17:53   #15
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Edward I done X383 's headlights and all I do is wax them when I do the car . Look like new. Also my modern car has been off the road for two weeks and X383 has done sterling service ferrying everyone around.
Many thanks for this and good to get an update on X383! Edward
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Old 16th December 2015, 01:23   #16
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T-Cut, might have to throw away my headlamp bulbs in the bottom of the box. Yes, they appear to have UV filtering these days.

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Old 17th December 2015, 02:36   #17
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Quote:
Originally Posted by klarzy-dials.com View Post
when remocing deeper pits and scratches (upto 0.5mm deep) then you need to remove that as a uniform layer across the whole light to prevent lensing.
This of course removes a thin gel like coating which can burn and build up on the lens if you have the abrasive moving too fast.

A good finishing compound like £m headlight poish and protect will leave some protection in the fine surface, but a sprayed on clear coat alowed to go very hard before fitting may be the best long term protection...

i am experimenting with that now...
Peter, let us know how you get on with this. My Xenon's are not going yellow, but the top protective layer is definitely peeling-off in places. I was considering cleaning the entire coat off using a 3M kit and then spraying with a coat of 2-pack clear-coat. But I am not sure how well this will resist the temperature of the main beams which are much hotter than the dipped Xenon beams.
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Old 17th December 2015, 07:17   #18
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Peter, let us know how you get on with this. My Xenon's are not going yellow, but the top protective layer is definitely peeling-off in places. I was considering cleaning the entire coat off using a 3M kit and then spraying with a coat of 2-pack clear-coat. But I am not sure how well this will resist the temperature of the main beams which are much hotter than the dipped Xenon beams.
Been done before so should ne ok
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Old 17th December 2015, 10:19   #19
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I was considering - - - spraying with a coat of 2-pack clear-coat.
Have you a link to this 2-pack stuff?

TC
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Old 17th December 2015, 10:33   #20
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Have you a link to this 2-pack stuff?

TC
Its just clear lacquer, the trouble is if you get a stone chip, that will let moisture underneath and it will look unsightly again.
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