# The science of windshield ice (WTF?) **URL:** \ **Category:** Factual Questions\ **Created:** [January 26, 2026, 3:47pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046 "2026-01-26T15:47:44Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [January 27, 2026, 12:52pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/21 "2026-01-27T12:52:21Z")
I usually garage my car. But when i leave it in a parking lot during a snow storm, i start the engine, turn on the defroster, and start removing snow from the top of the car, and the big swaths is loose able from the glass, and the pile of snow behind the car where the plow came by. By the time I’ve done that, the windshield is warm enough that any adhering ice has come loose, and i can just gently brush it away. (Check that the tail pipe is clear of snow before starting it.) ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [January 27, 2026, 1:31pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/22 "2026-01-27T13:31:34Z")
I personally use a little space heater and let it run inside the car for a few hours. The one issue I sometimes run into is that as the snow melts from the roof it can drip down and freeze on the doors, freezing the doors shut. But otherwise it works great for cleaning off the car (windows and roof) and warming up the interior. Plus I don’t have to worry about someone stealing my car if I left it running in the driveway to warm up, which happened to my neighbor a couple of years ago. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 27, 2026, 1:37pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/23 "2026-01-27T13:37:12Z")
> [@Mk\_VII](#): > > My Ford has electric elements in the windshield; it only takes a couple of minutes before it starts to flake off under the wipers. I value this more than anything else about the car. Wow. Back when I lived in snow country I always thought that feature should be mandatory on all cars to stop the people who brush a tiny porthole in their windshield then drive off, hoping the wind will finish cleaning off their car and the rest of the windshield. Hint: it won’t; at least not any time soon. But instead I had / have never heard of any car with those wires in the windshield until just now. Meanwhile most cars have that heated glass feature available at least as an option for the rear window. If you don’t mind my asking, what year & model Ford? I see you’re in the UK which is probably the most significant factor. AFAIK, in the USA where I am, such sensible inventions are prohibited. ---
**Author:** ![Maserschmidt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/maserschmidt/32/18829_2.png) [@Maserschmidt](https://boards.straightdope.com/u/Maserschmidt)\ **Post date:** [January 27, 2026, 1:53pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/24 "2026-01-27T13:53:57Z")
> [@LSLGuy](#): > > But instead I had / have never heard of any car with those wires in the windshield until just now. Meanwhile most cars have that heated glass feature available at least as an option for the rear window. I remember Ford tried those in the US for a while in the 80s (and maybe 70s, according to the internet). I’m not sure what killed them, but I imagine replacing them was expensive and a pain. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [January 27, 2026, 1:58pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/25 "2026-01-27T13:58:02Z")
Here’s a list of cars available in the US that had the option of heated windshields as of 2023. Hint: open up you wallet… [https://www.cars.com/articles/which-cars-have-heated-windshields-476235](https://www.cars.com/articles/which-cars-have-heated-windshields-476235) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 27, 2026, 2:11pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/26 "2026-01-27T14:11:45Z")
Great cite; thank you. That list is pretty much synonymous with “European-made EVs”. Which is not terribly surprising. For sure it’s more power-efficient for an EV to embed wires in a windshield than it is to have an electric element heating air to then be blown at the same windshield with an electric fan. And the car-making parts of Europe are generally places with snowy winters. Over half the USA landmass, and well over 2/3rds of the population, gets snow every year. That hot windshields aren’t already common here is a bit surprising. But I bet they’re coming. Sooner if we have a sane government. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [January 27, 2026, 2:22pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/27 "2026-01-27T14:22:59Z")
> [@LSLGuy](#): > > Over half the USA landmass, and well over 2/3rds of the population, gets snow every year. That hot windshields aren’t already common here is a bit surprising A good percentage of that 2/3rds live in places where chipped and broken windshields are almost as common as a flat tire. When I lived in the Pacific NW, replacing a windshield was almost once a year like clockwork. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [January 27, 2026, 3:24pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/28 "2026-01-27T15:24:22Z")
Here in Hokkaido, the vast majority of cars have remote starters. At night, I turn on the defroster on high and it does a good job on the windshield. The remote starters keep the doors locked so the car can’t be stolen. The engine shuts off of the door is opened. ---
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [January 27, 2026, 3:34pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/29 "2026-01-27T15:34:49Z")
> [@Elmer\_J.Fudd](#): > > chipped and broken windshields are almost as common as a flat tire That seems insane to me… In thirty years of driving I’ve replaced a windshield… Twice, I think. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [January 27, 2026, 3:38pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/30 "2026-01-27T15:38:15Z")
If you ever lived anywhere near a quarry, you would know what I mean. ---
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [January 27, 2026, 3:39pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/31 "2026-01-27T15:39:10Z")
I’m sure the lack of people/traffic here in Wyoming helps, too… ---
**Author:** ![Maserschmidt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/maserschmidt/32/18829_2.png) [@Maserschmidt](https://boards.straightdope.com/u/Maserschmidt)\ **Post date:** [January 27, 2026, 3:39pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/32 "2026-01-27T15:39:28Z")
> [@TokyoBayer](#): > > The remote starters keep the doors locked so the car can’t be stolen. The engine shuts off of the door is opened. Remote starting was optional on our Subaru, and we got it, and it is the option I will now include if we ever get a new car again. It’s awesome. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [January 27, 2026, 3:50pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/33 "2026-01-27T15:50:48Z")
I can start the car from inside my apartment so I don’t even have to go outside. ---
**Author:** ![Maserschmidt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/maserschmidt/32/18829_2.png) [@Maserschmidt](https://boards.straightdope.com/u/Maserschmidt)\ **Post date:** [January 27, 2026, 3:57pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/34 "2026-01-27T15:57:39Z")
That’s awesome. We can do so from inside our house, and even from inside the church if we park on the near side and pass by the window. It’s like magic! ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [January 27, 2026, 4:02pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/35 "2026-01-27T16:02:48Z")
> [@Stratocaster](#): > > There are instances where it’s fifteen exhausting minutes just to scrape a little porthole on the driver side. I never scrape ice off of my windshield. I come out early, start my car, warm it up, and defrost the windshield. Electric defrosters take care of the back window and the side mirrors. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 27, 2026, 5:03pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/36 "2026-01-27T17:03:11Z")
> [@Elmer\_J.Fudd](#): > > A good percentage of that 2/3rds live in places where chipped and broken windshields are almost as common as a flat tire. When I lived in the Pacific NW, replacing a windshield was almost once a year like clockwork. Sounds more like the difference between (sub-)urban and rural, not snow or not. Like @Kron, I’m amazed at the idea of frequent windshield replacements. If the issue is quarries as you say, those aren’t correlated with cold weather either. My DL is 51 years old. I’ve replaced 2 windshields since Day 1. I’ve had more flat tires that I can’t now recall specifically to provide a count. But I do know that since moving to FL not quite 12 years ago I’ve had two flat tires. One of which was a blowout of a dry-rotted tire and the other of which was running over a big hunk of metal on a freeway. Conveniently, but expensively, those were both run-flat tires. On the one and only car I ever had which had those. Don’t have them now, nor previously. I’ve certainly developed additional slow leaks from road hazards that needed plugging in the next couple weeks, but the last time I installed a spare tire or used fix-a-flat goop to keep driving was the early 1990s. I sold that car in 1994. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [January 27, 2026, 5:17pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/37 "2026-01-27T17:17:43Z")
> [@LSLGuy](#): > > Over half the USA landmass, and well over 2/3rds of the population, gets snow every year. That hot windshields aren’t already common here is a bit surprising. I wonder if they’re more prevalent in Europe because they’re less likely to have garages? I don’t have a per-capita garage statistic, but my gut tells me car buyers in the US who can afford the up-charge of a heated windshield are also more likely to have a garage that makes it unnecessary. Also snow doesn’t benefit from a heated windshield, but frost and ice do. Are those conditions more common in Europe? ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [January 27, 2026, 5:27pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/38 "2026-01-27T17:27:31Z")
I think another reason for ice adhesion is that the critical surface tension of glass is pretty high. This means water can form a sheet on the glass, rather than remaining as isolated blobs. To say this in more precise and generalized terms, the interfacial surface energy of a water-glass interface is low. If Rain-X improves the release, it does so by this mechanism. ---
**Author:** ![Stratocaster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stratocaster/32/16393_2.png) [@Stratocaster](https://boards.straightdope.com/u/Stratocaster)\ **Post date:** [January 27, 2026, 6:20pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/39 "2026-01-27T18:20:16Z")
> [@Dinsdale](#): > > I’m assuming this is exaggeration, no? A lifetime in the Chicago area, and I’ve never needed 15 minutes to clear enough to drive. If I were spending 15 minutes, I’d turn the defroster on high and go back inside for another cup of coffee. Yes, a bit of an exaggeration, though it’s taken me almost that much time to do a proper scrape of all the windows. I am also usually a “let the defroster run and do the work” guy, though on occasion some stubborn ice took me by surprise and I had to frantically scrape a porthole so I wouldn’t be late for work. And, yes, I know that’s dangerous and I’m deeply ashamed. ---
**Author:** ![Mk\_VII](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)\ **Post date:** [January 28, 2026, 7:03pm UTC](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046/40 "2026-01-28T19:03:18Z")
> [@LSLGuy](#): > > If you don’t mind my asking, what year & model Ford? I see you’re in the UK which is probably the most significant factor. It’s a 2005 Focus. [Previous page](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046.md?page=1) [Next page](https://boards.straightdope.com/t/the-science-of-windshield-ice-wtf/1027046.md?page=3)