# Does putting a sun visor in your car's windshield weaken the glass?

**URL:** <https://boards.straightdope.com/t/does-putting-a-sun-visor-in-your-cars-windshield-weaken-the-glass/197212>\
**Category:** Factual Questions\
**Created:** [August 23, 2003, 8:20pm UTC](https://boards.straightdope.com/t/does-putting-a-sun-visor-in-your-cars-windshield-weaken-the-glass/197212 "2003-08-23T20:20:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![raz](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@raz](https://boards.straightdope.com/u/raz)\
**Post date:** [August 23, 2003, 8:20pm UTC](https://boards.straightdope.com/t/does-putting-a-sun-visor-in-your-cars-windshield-weaken-the-glass/197212/1 "2003-08-23T20:20:38Z")

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Somebody told me that it’s not a good idea to use those cardboard sun visors for your car because, over time, they can weaken the glass. Is there any truth to this?

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**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\
**Post date:** [August 23, 2003, 8:22pm UTC](https://boards.straightdope.com/t/does-putting-a-sun-visor-in-your-cars-windshield-weaken-the-glass/197212/2 "2003-08-23T20:22:49Z")

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How would that occur?

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**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\
**Post date:** [August 23, 2003, 8:42pm UTC](https://boards.straightdope.com/t/does-putting-a-sun-visor-in-your-cars-windshield-weaken-the-glass/197212/3 "2003-08-23T20:42:05Z")

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Maybe the idea is that the reflected sunlight (heat) would damage the glass.

I can tell you that my 13-yr old Civic still has its original windshield. And for 9 of those years I used a reflective “sun shield” in it as it was parked at the office for 9 hours each day.

It sounds dubious to me.