# Windows you can turn "on" and "off" **URL:** \ **Category:** Factual Questions\ **Created:** [June 26, 2003, 3:49am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448 "2003-06-26T03:49:03Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![tonbo0422](https://avatars.discourse-cdn.com/v4/letter/t/b5e925/32.png) [@tonbo0422](https://boards.straightdope.com/u/tonbo0422)\ **Post date:** [June 26, 2003, 3:49am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/1 "2003-06-26T03:49:03Z")
One would think this would be a major seller. Who needs blinds? Simply turn a switch and your bay window goes from clear to opaque (meaning black.) Why have I never heard of this? Is it just because the technology is too expensive? There would be no more need for curtains. You could even adjust the opacity to suit your needs. This just doesn’t sound like an impossible task like creating a force field, and it would quite possibly be the hottest-selling thing in the world–a window you can turn on or off. Why hasn’t it been done? ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [June 26, 2003, 4:05am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/2 "2003-06-26T04:05:10Z")
I saw a TV show only days ago about a shop in Florida that has a toilet that works like this. Turn a handle and the walls are no longer see through. I’ll see if I can find out more. ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [June 26, 2003, 4:09am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/3 "2003-06-26T04:09:09Z")
[Here](http://travel.discovery.com/fansites/worldsbest/bathrooms/bathrooms10.html) it is Sloan’s. ---
**Author:** ![Manduck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manduck/32/256_2.png) [@Manduck](https://boards.straightdope.com/u/Manduck)\ **Post date:** [June 26, 2003, 4:55am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/4 "2003-06-26T04:55:13Z")
I don’t get it. When you’re eating ice cream, why would you want to look at a toilet, even if it’s unoccupied? ---
**Author:** ![nebco9](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@nebco9](https://boards.straightdope.com/u/nebco9)\ **Post date:** [June 26, 2003, 5:06am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/5 "2003-06-26T05:06:27Z")
They have them now, but kinda expensive. Try Google for “electrochromic windows” ---
**Author:** ![Trigonal\_Planar](https://avatars.discourse-cdn.com/v4/letter/t/0ea827/32.png) [@Trigonal\_Planar](https://boards.straightdope.com/u/Trigonal_Planar)\ **Post date:** [June 26, 2003, 5:08am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/6 "2003-06-26T05:08:12Z")
Are you asking if such a product exists? Cuz the answer is yes, such “windows” do exist. Or, are you asking why aren’t they a major seller? Presumably because the technology is so expensive and they aren’t produced in mass quantities yet. ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [June 26, 2003, 5:13am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/7 "2003-06-26T05:13:28Z")
Apparently you can get them for car license plates so that they look clear normally but become opaque if they detect a camera flash so speed cameras cant catch them. Obviously, they are illegal and fairly expensive as well. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 26, 2003, 6:37am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/8 "2003-06-26T06:37:42Z")
One problem with liquid crystals is that even when “OFF” (clear), it only transmits up to 50% of the light. It’s a fundamental limitation because a polarizing filter is an essential part of a liquid crystal device. I think I heard about a cheaper method that uses an opaque fluid. It’s pumped into the gap between two layers, or something like that. Sounded like a good idea to me, but I don’t know if anyone makes it. ---
**Author:** ![Shade](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@Shade](https://boards.straightdope.com/u/Shade)\ **Post date:** [June 26, 2003, 7:43am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/9 "2003-06-26T07:43:49Z")
And if it goes wrong? It’s very cool idea, I’ll grant you, but curtains are a tried, tested and effective way of making windows opaque. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 26, 2003, 9:23am UTC](https://boards.straightdope.com/t/windows-you-can-turn-on-and-off/184448/10 "2003-06-26T09:23:00Z")
In Singapore, the elevated trains often pass apartment blocks; in order to stop the passengers peering into people’s homes, the windows are programmed to fade to opaque and back at just the right points on the journey.