A woman I know says her son's Transition lenses darken in the car. He sits in the back seat on the side. Are the side windows allowing his lenses to darken? Is she just thinking they darken in the car because they darken so quickly when he gets out?
A woman I know says her son's Transition lenses darken in the car. He sits in the back seat on the side. Are the side windows allowing his lenses to darken? Is she just thinking they darken in the car because they darken so quickly when he gets out?
Front windshield is lanimated glass probably with UV filter. Side windows are tempered glass possibly without UV filter.
Chip:p
Originally Posted by chip anderson
Thanks, Chip. That is what I am wondering. Do you know this Chip or is it an educated guess?
I know about the types of glass for sure, as to whether the UV filter is in side glass: I don't know for sure but I doubt that it's in there.
It's also possible it would be in some cars and not in others. Probably in all windshields (windscreen for you North of the Border)
Chip
I was just playing this weekend. I was on a road trip and forgot my suns.
I could take off my Transition specs and set them on my lap facing the side window. They got surprisingly dark. When I put them on they start to lighten immediately until they were almost completely clear.
Conclusion: No UV filter on the side windows.
Further experimentation showed that there is a UV filter in the moonroof glass.
Is there really a UV filter in the moon roof glass or is it just darker (which is the same as a filter)? I don't really have the facts about the differences in car glass, but you have to look at a few other things...the amount of tint in the glass, the thickness of the glass, the angle of incidence of the sunlight, whether it is hitting the glasses directly or indirectly, and the distance of the glasses from the car windows.
Obviously the darker the tint in the car glass, the more UV that will be blocked. Even clear glass will block some. Secondly, if an adult is sitting high up in the car, avoiding a direct hit by the sun's rays, his transitions will not get that dark. However, if a small child is sitting low in the car, and sunlight is coming in from the side and striking him right in the face, and he happens to be leaning the side of his face on the window, his lenses will change more.
As most of you know, Transitions Optical's parent company is PPG Industries Inc. PPG is a major player in OEM and replacement auto glass. Early in 2008, these business units were spun off but PPG is a minority partner in the new set up.
A majority of North American vehicles are fitted with PPG original equipment glass or windows with similar specs of the PPG autoglass to meet OEM requirements of the respective automakers.
Laminated auto glass (a urethane interlayer between two sheet of glass) windshields have been mandatory in the US since the early 1960's. PPG first offered this technology in 1928. These windows absorb on average 100% UVB and 80% UVA.
The side windows, until recently, are not typically laminated. These windows block an average of 97% UVB and 37% UVA. This is why you can pick up a tan on your left arm on long drives and most likely reason a photochromic lens will activate under right circumstances!
UV drives the chemical reaction, dyes today are sensitive and a little UVA above 365nm will go a long way to partially activate a lens.
If you have a good aftermarket tint applied, the UV block on these side windows can be very close if not at 100%.
In recent years, the PPG Safe and Sound autoglass that features laminated safety glass in all windows and PPG Sungate IR absorbing autoglass are fitted in most high end or specialty cars. These two technologies block 99% of all UV, Sungate actually has an SBF rating of 50+.
PPG has a line of OEM Solar branded autoglass too. This is the look that has a reflect color from a G15 appearance to various grays depending on the angle of the sun.
The sunroof question...The darkness of a window does not translate to UV protection. It would be the same with tinting a plain CR39 lens down to 12% transmission. Unless the CR39 was cast with a UV absorber or the dyes had a uv component, the lens will still block the same amount of UV as when it was a clear CR39 lens without any extra UV treatments. (I believe a bare, no frills CR39 plano 2mm CT lens is a 92% UVA block).
So, the dark glass moon roofs need to be treated and from what I understand, the OEM and top end aftermarket windows do block UV and some IR properties too.
Jim
Jim Schafer
Retired From PPG Industries/
Transitions Optical, Inc.
When you win, say nothing. When you lose, say even less.
Paul Brown
My Honda has U,V, in all the window's to protect agianst the interior fading. It works, My interior still looks new and my transitions don't darken at all in my car no matter were I sit. :)
Jim:
I follow what say but moon roofs are going to be 6 mm + thick. Doubt that they are letting much UV in with or without addittives.
Chip
Alright Jim,
I get the UV properties of autoglass.
What I want to know is why PPG has not created a photochromatic autoglass? I would love it if the autoglass adjusted like transitions. Surely I can't be the first person to think of that. Is there a reason that it can't be done?
I'll take a 5% royalty check on all proceeds:bbg:
Properly medicated for your protection.
Didn't lighten up fast enough when one went in to tunnels and other areas where it got dark in a hurry! Was even an electronic (like the expensive windows one can get) version abandoned for the same reason.
Chip
Damn the "MAN" and silly safety rules!
I figured there was a reason.
Not to many tunnels here in Florida, driving through water proves to be a bit difficult.
:)
Properly medicated for your protection.
Hi BMH,
In 1984 GM and PPG launched photochromic windshields on certain Olds Toronado's and Cadillac El Dorados (same windows!). The problem was extreme cold caused delamination of the glass and interlayer. All the windows were replaced with conventional glass.
What they have done now with either the Sungate or the Solar series, is the windshield has an architectural coating that looks like a light mirror. There was a press release featuring a black Chrysler 3000 with a electric blue mirror windshield, looks very futuristic.
Bad news for our industry is that the window offers very good vision in all weather and cuts glare to nothing, no need for driving lenses. I found a link for these windshields http://corporateportal.ppg.com/NA/OE...high_kroma.htm
Jim
Last edited by Jim Schafer; 10-24-2008 at 02:36 PM. Reason: adding a link
Jim Schafer
Retired From PPG Industries/
Transitions Optical, Inc.
When you win, say nothing. When you lose, say even less.
Paul Brown
How about putting the photo version on the side windows- that would be great for the Florida sun and still clear at night.
Craig
Now that they use those crappy Chinese window motors that die one every 6 months or so (@ $160.00 ea), you don't want anything else electronic to break down.
Chip
My T6 attain about 20% darkening in my Yaris but absolutely nothing in the PT, and yes, only when the sun's shining on them thru the side window. Now, my old T5's do not darken at all in the Yaris, even if I hold them directly up to the window.
Also, my T6's, on a sunny day inside my house, darken considerably (30% or thereabouts if I'm sitting in the livingroom where the huge high windows shine daylight) and my T5's only show a tad bit of colour.
Just my 2cents
You no's somebody would have to ask. What's a yaris? Sounds like a Litowenian salid.
Interesting. I used to notice that my husband's Transitions (not sure which one) used to darken a little when he sat inside next to the window in the sunlight. We got new windows recently and I think they might not anymore.
The Yaris is Toyota's 'econobox' answer to high gas prices and low carbon emissions. Here's the link to the pic I posted in the summer of my Yaris.
http://www.optiboard.com/forums/atta...7&d=1216268128
Just so's ya know the difference between a Yaris and a Lithowanian salad.:D
I've personally made transmittance measurements of many types of inorganic optical materials over the years. The only inorganic optical materials I have encountered that transmit UV are SiO2 or quartz, and Al2O3 or aluminum oxide (saphire). Auto manufacturers are not using these materials as side windows. If darkening is occuring it must be from a slightly open window, allowing UV to be incident on the lenses, or from thermal induced effects.
Best regards
Last edited by Sunxprt; 02-27-2009 at 05:43 PM. Reason: include thermal effect
I usually hear claims from transition speakers at seminars that rolling down the side window will cause them to darken. But I only hear this after someone has asked the question about why don't they darken in cars. They will however definitely darken in convertibles if the top is down.
Chip
I'll take a pic on my way to work this morning of the density of my lenses- I will have been in the car on my daily commute for at least 40 minutes without the window down, and with the sun at approx. the 9:00 position (directly at the drivers side window) and since its below the freezing mark outside the temperature will be a comfortable 70 degrees inside the car.
This DOES NOT occur when I'm driving the PTCruiser, only the Yaris, all factors being equal. Further, I can hold my glasses up to the side window glass and immediately see the darkening occur.
insight
This is great feedback....answers a few questions and myths all in one great section !! thanks for the info everyone..it helps me pass it on to our new hires when dealing with myths & rumors they hear from walkins.
keep up the great work everyone
be safe !!
Lens Whisperer
Really appreciate all the info...and discussion before and after :)
Still re-learning the biz after over a decade away and come here daily for more knowledge.
Thanks to all, and here, Jim especially.
Don
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