I have a '90 4-Runner with tinted windows. I recently noticed a "dot" pattern on four of the windows with no pattern on the other two. I took it to an auto tinting place and asked what was causing the problem. They looked at the window and didn't see anything. Then one of the them asked if I was wearing polarized sun glasses. I told them yes and I purchased them about a week ago. I took the glasses off and the pattern disappeared.
Any ideas why this pattern appears on some tinted windows but not others?
Tint film is polarized too. Mine create a nauseating rainbow pattern when I wear polarized shaded. Such things are common when you look through 2 polarized materials. It depends on the orientation of the polarization.
What you describe may not be related to the tinting at all. Many curved windows (such as the side and back windows of many cars) are tempered glass, and the dots you see are the locations of the supports when the window was curved and tempered. The supports tend to cause an alignment of the glass molecules (just like the polarized glasses have all of their glass aligned in a particular way to reduce glare). If you'd ripped off all of the tinting, you may have found the windows themselves were the culprit. Of course, certain tinting films also have their own polarizing characteristics, but if you have a polarized tint film on a window with polarized spots, you may be able to see the effect without the polarizing sunglasses.
By the way, a number of years ago (say 10 or 15, the memory isn't what it used to be) there was a proposal to mandate polarization of all windshields at a 30 degree angle in a certain direction, along with the polarization of all headlights at 30 degrees in the same direction. Thus, you would see fine, but the glare of oncoming cars would be reduced considerably. (if they were each 45 degrees, you might not even notice the oncoming headlights during the day, because the combined angle is 90 degrees, which is the greatest effect of the polarization). I'm not sure why it didn't come about, but it did seem like a decent idea at the time. Of course, it would play hell with wearing polarized sunglasses while inside the car, so maybe that was the reason...
Thanks
--Rick AH7H
Gr> I have a '90 4-Runner with tinted windows. I recently noticed a "dot"
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