The recent storm, and all the shoveling and scraping, got me thinking. I get why ice might form on my windshield overnight. But why in the world is it often so difficult to scrape off? There are instances where it’s fifteen exhausting minutes just to scrape a little porthole on the driver side.
ISTM that if there’s a surface where it should be super-easy to knock ice from, it would be glass, which is smooth as, well, glass. I mean, WTH is the ice clinging to, what nook, cranny, or crevice? Shouldn’t one bash with the meaty part of your fist sent it shattering onto your hood?
BTW, I’m 65-years old, so it took a while for the question to occur to me (don’t judge me).
First, even though your windshield looks lovely and smooth, it has a lot of imperfections, and those become opportunities to increase adhesion. Second, ice is less brittle at or near freezing; ice become more brittle the deeper the freeze gets. Third, when freezing is gradual, adhesion is higher because water can find its way into those imperfections more easily.
If the ice was thin enough and your windshield was more flexible than it is, this would work. But they’re not.
Hitting the ice does nothing; it’s flexing the ice that will detach it from the window.
Cold glass is quite stiff. Your ability to hit the ice hard enough is limited by not also caving in your windshield. You can certainly see fail videos of people whacking their car windows / windshields hard enough to break the glass. A bunch of ice does get dislodged. But a bunch is also still sticking because it’s less brittle than the glass is.
Yesterday afternoon I started up the iced-over car in the driveway and let it idle for a long time with the defrosters on to loosen the ice. When I went back out with the ice scraper it wasn’t too hard to get the ice off the windows. As I was working on the windshield, the mass of ice and snow covering the front of the car began to shift, and suddenly all of it started shifting forward, creating an impressive mini-landslide.
Fortunately I was standing to the side of the car and didn’t get crushed.
Some mornings I’ll get out to my car when it’s near freezing and covered in dew. I’ll swipe the windshield with a finger to confirm it’s just dew, but moments later when I start the car and turn on the wipers, the dew has frozen over and I have to get back out and scrape it anyway. A neat phenomenon but annoying in the moment. I assume it has something to do with the vibration of the motor, or something like that.
It’s possible that the dew has become “supercooled water”: water that remains in its liquid state despite being below 0 C. Part of what lets it stay that way is that it isn’t being disturbed in any way, but once you open the car door, turn on the engine, etc., the vibrations shake it out of the supercooled state, and it freezes.
The best fail video is the guy pouring his coffee over the windshield - the entire windshield crazes into little pieces. (McDonalds coffee is HOT as we know).
Anyone with an older car can see the windshield has tiny pits that make it more irritating to see on bright glaring sunny days.
That makes sense. I think I’ve seen videos demonstrating the same effect with bottled water stored carefully in the freezer, then rapped on the countertop and quickly freezing over.
I remember when I had the windshield replaced on an older car. I had washed the old windshield not long before so the experience was fresh in my mind. When I cleaned the new glass for the first time I was astonished at how effortlessly the towels wiped over the new glass.
Also note that when your side glass is iced over you can sometimes lower the window and the ice remains intact while the glass slides away.
One Big Easy button from my era in ice country is Glass Wax. Freshly applied before crappy weather it’s a great help in reducing ice adherence to windshields. Back when I was living there I was still using a pink can of the OG stuff. I can’t recommend a current brand but there are several.
Iced windshields are very rare in San Jose, but I’ve had it happen a time or two. My usual fix was to turn on the hose and spray the windshield with the wipers on. That solution failed one morning when the hose was frozen too and broke in half when I went to uncoil it.
I used to remember it being such a pain to get ice off the windshield, but with my car (2016 model) just turning on the front windshield defroster for about ten minutes goes a long way. Usually snow and ice just slide right off.
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.
Definitely. When I’ve had to scrape more than just a light coating of ice off of a car’s windows, my general strategy has always been to let the car run for 10 minutes or so, until the engine is warm enough to be supplying hot air to the defrosters, and let that get the windows warm enough that scraping is easier.
One way to make the ice easier to remove is to use a hydrophobic coating, like Rain-X. The coating will seal the small pits to make the glass smoother, and the hydrophobic property will make it harder for the ice to bond to the glass.
A spray bottle of 2/3 isopropyl alcohol and1/3 water melts windshield ice instantly. Supposedly doesn’t hurt the car finish. I use it while I’m waiting for the car to finish warming up. That’s in Seattle, though. Idk how well that works in minus zero temperatures.
I’m a RainX user and one benefit is that ice and frost come off quite easily. This past storm was one of the worst in a long time around here with snow followed by sleet and then rain and then freezing temps. The stuff practically slid of with the use of small scraper. Get some. Maybe put a fresh coat on when snow and ice are expected. (BTW, my last application was a month or more back.)
).