# Homemade windshield deicer **URL:** \ **Category:** Factual Questions\ **Created:** [December 14, 2006, 4:25am UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078 "2006-12-14T04:25:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Esprix](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/esprix/32/7899_2.png) [@Esprix](https://boards.straightdope.com/u/Esprix)\ **Post date:** [December 14, 2006, 4:25am UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/1 "2006-12-14T04:25:08Z")
Gosh, it’s been a while, hasn’t it? 😉 Anywho, I’m looking for recipies for homemade windshield deicer solution. I’ve got a handy dandy spray bottle and I want to be able to get rid of that nasty frost in the mornings. My understanding is that normal windshield washer fluid isn’t so hot because it’ll just re-freeze if it’s cold out. Salt water to mee seems like it’d make a mess when it dried. And we all know adding hot water to ice cold glass is a no-no. I’ve found a couple of recipies online, but they involve weird chemicals I’d have to buy special (magnesium chloride hexahydrate, for example). Isn’t there something that can be made from your usual car or home products? So, Teeming Millions - got anything for me? 😃 Esprix ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [December 14, 2006, 5:01am UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/2 "2006-12-14T05:01:27Z")
A 30% methanol/water mix would work; it [freezes at -15 °F](http://www.nugentec.com/FAQ/Freezing%20Point%20Flash%20Points.htm). However, methanol is pretty flammable, and is not something you’d want floating around as a gas in your engine compartment. [Aircraft Deicers](http://72.14.203.104/search?q=cache:BvwpoOFSChsJ:www.p2pays.org/ref/15/14735.pdf+%22water+methanol%22+deicer&hl=en&gl=us&ct=clnk&cd=3&client=firefox-a) seem a safer bet: > [@](#): > > While actual compositions of ADFs are proprietary, when diluted for use they are approximately as follows: propylene glycol, 20-30%; tolyltriazole, 0.05-0.2%; surfactants and viscosity enhancers 1-2%; other additives 1-2%; water 65-80%. Forget the tolyltriazole, which is a corrosion inhibitor, and go with a straight 25% solution of [propylene glycol](http://en.wikipedia.org/wiki/Propylene_glycol). It’s sold as a non-toxic antifreeze. You’ll probably want to look for a brand without the usual fluorescent dye. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [December 14, 2006, 5:41am UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/3 "2006-12-14T05:41:30Z")
There’s always a plastic sheet either held in place by the front doors or some small magnets. Frost & ice form on that instead of the windshield. (Old volly fireman’s trick) 😃 ---
**Author:** ![Baffle](https://avatars.discourse-cdn.com/v4/letter/b/dec6dc/32.png) [@Baffle](https://boards.straightdope.com/u/Baffle)\ **Post date:** [December 14, 2006, 5:47am UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/4 "2006-12-14T05:47:05Z")
Around here you can buy winter washer fluid that freezes at something like -45. ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [December 14, 2006, 2:23pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/5 "2006-12-14T14:23:56Z")
Yeah, there are definitely two kinds that are sold. I made the mistake of buying some on a trip to Vegas that was not freeze proof (never assume). The whole shebang froze up one the way back home over the Rockies. I can buy the low-temp stuff for about 2 bucks a gallon. Probably less if I bothered to shop for it. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 14, 2006, 3:10pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/6 "2006-12-14T15:10:30Z")
FWIW I just use warm (not hot) water. I don’t know how cold it gets in San Diego, but I’ve only had problems with refreezing when it’s got very chilly (for southern England) - say below 23-24ºF or so. ---
**Author:** ![Esprix](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/esprix/32/7899_2.png) [@Esprix](https://boards.straightdope.com/u/Esprix)\ **Post date:** [December 14, 2006, 3:19pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/7 "2006-12-14T15:19:28Z")
[QUOTE=Colophon] I don’t know how cold it gets in San Diego… [/QUOTE] Trust me, if I were still in San Diego, this wouldn’t have been posted - it very rarely gets frosty cold. I’m in the northeast, which gets just a tad chilly from time to time. 😉 Esprix ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [December 14, 2006, 3:22pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/8 "2006-12-14T15:22:57Z")
Around here, we use “go out and start the car with the heater and defroster at full blast, then go back inside and finish your coffee.” Also, always leave at least a quarter tank of gas in your car so as to avoid running the tank dry during this process, which is counter-productive in the extreme. For actual solution, we just use straight windhshield washer fluid, which freezes at about -25 degrees. Has propylene glycol in it, as mentioned above. It works to clear frost off, but if it refreezes, at least it’s pretty. Hope you’re not moving at the time… ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [December 14, 2006, 3:30pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/9 "2006-12-14T15:30:13Z")
Why not just use isopropyl alcohol? Cheap, readily available, almost instantly mixes with ice/frost to form a (more dilute) solution, and won’t leave an oily film on the glass as I fear propylene glycol would. Freezing point for a 50% solution is -5, 70% is -20, 90% is -70 (degrees Fahrenheit). ---
**Author:** ![According\_to\_Pliny](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@According\_to\_Pliny](https://boards.straightdope.com/u/According_to_Pliny)\ **Post date:** [December 14, 2006, 3:32pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/10 "2006-12-14T15:32:48Z")
I lived four years in Minnesota, and would just throw a pail of warm water over the thick layers of sleet and pack ice. Squeegee off and it won’t refreeze. People who say the glass can’t take it are unaware of how temperature - dimensional stable windshields are, like Pyrex. ---
**Author:** ![bordelond](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bordelond/32/150_2.png) [@bordelond](https://boards.straightdope.com/u/bordelond)\ **Post date:** [December 14, 2006, 3:49pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/11 "2006-12-14T15:49:10Z")
[QUOTE=According to Pliny] I lived four years in Minnesota, and would just throw a pail of warm water over the thick layers of sleet and pack ice. Squeegee off and it won’t refreeze. People who say the glass can’t take it are unaware of how temperature - dimensional stable windshields are, like Pyrex. [/QUOTE] Good posting. I’ve had no problems with hot-tap water (140 F?) on iced-over windshield glass … been doing it for years. The coldest weather I’ve ever had to deal with was about 10-12 F, though … things might be different in places that regularly go below zero. ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [December 14, 2006, 4:04pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/12 "2006-12-14T16:04:49Z")
[QUOTE=bordelond] Good posting. I’ve had no problems with hot-tap water (140 F?) on iced-over windshield glass … been doing it for years. The coldest weather I’ve ever had to deal with was about 10-12 F, though … things might be different in places that regularly go below zero. [/QUOTE] It doesn’t necessarily even have to be warm. I just turn the hose on the windshield. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [December 14, 2006, 4:31pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/13 "2006-12-14T16:31:27Z")
I use warm water on the windshield to remove ice. I started doing it when I figured ice half an inch thick can’t be safely removed by chipping at it. I know there’s a chance of cracking, but I don’t worry about it until the temps get into the single digits. I have seen a windsheild in a new truck cracked from it’s defroster heat on a very cold day. After that you could hear the crack enlarging when the defroster was on. It took about a week until the windshield was changed. ---
**Author:** ![GingerOfTheNorth](https://avatars.discourse-cdn.com/v4/letter/g/cdc98d/32.png) [@GingerOfTheNorth](https://boards.straightdope.com/u/GingerOfTheNorth)\ **Post date:** [December 14, 2006, 4:59pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/14 "2006-12-14T16:59:31Z")
[QUOTE=bordelond] Good posting. I’ve had no problems with hot-tap water (140 F?) on iced-over windshield glass … been doing it for years. The coldest weather I’ve ever had to deal with was about 10-12 F, though … things might be different in places that regularly go below zero. [/QUOTE] Esprix has moved to Maryland, where it really doesn’t get that cold. Our average low winter temperature runs between 28F and 38F. I don’t really consider Maryland to have a winter; could be the years I lived in the Arctic. ---
**Author:** ![bordelond](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bordelond/32/150_2.png) [@bordelond](https://boards.straightdope.com/u/bordelond)\ **Post date:** [December 14, 2006, 5:08pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/15 "2006-12-14T17:08:18Z")
[QUOTE=GingerOfTheNorth] Esprix has moved to Maryland, where it really doesn’t get that cold. Our average low winter temperature runs between 28F and 38F. I don’t really consider Maryland to have a winter; could be the years I lived in the Arctic. [/QUOTE] I was referring to the time I lived in Jackson, MS! Every winter, there were at least a few days below 20 F … and 3 or 4 weeks where overnight temps below 30 were the norm. Snow was fairly rare, though. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [December 14, 2006, 5:09pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/16 "2006-12-14T17:09:36Z")
The way to break windshields with hot water is to be in a hurry and throw a full 3-5 gallons of hot water on a windshield that is real cold and has little ice that need melting. When that hits the whole thing all at once, ‘poof’ goes the windshield. If the water is not too hot and poured slowly from the top and just worked across the windshield and the heater is starting to help from the inside, you can go for over 47 years of doing it without breaking a single windshield, side glass and rear window also. YMMV \*:: I do hate washer fluid that will freeze up after is gets squirted on the windshield. :: \* ---
**Author:** ![LateComer](https://avatars.discourse-cdn.com/v4/letter/l/b5ac83/32.png) [@LateComer](https://boards.straightdope.com/u/LateComer)\ **Post date:** [December 14, 2006, 5:27pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/17 "2006-12-14T17:27:40Z")
[QUOTE=GingerOfTheNorth] I don’t really consider Maryland to have a winter; could be the years I lived in the Arctic. [/QUOTE] I suppose you don’t live in Frostburg. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [December 14, 2006, 7:50pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/18 "2006-12-14T19:50:53Z")
[QUOTE=According to Pliny] I lived four years in Minnesota, and would just throw a pail of warm water over the thick layers of sleet and pack ice. Squeegee off and it won’t refreeze. People who say the glass can’t take it are unaware of how temperature - dimensional stable windshields are, like Pyrex. [/QUOTE] Ditto, WI resident here too. Been using warm tap water for the last couple years without incident, not hot just warm. Pour it over the door locks, mirrors, and all the windows if it’s really bad. Never had the locks or windows feeze up either. I just noticed that RainX makes some window washer stuff that’s supposed to coat the window with RainX when you use it. I bought it yesterday but haven’t been able to test it out yet. I like to use RainX in the rainy season because it keeps the rain from sticking to the glass and it should also keep ice from sticking to the windshield, I believe. ---
**Author:** ![VunderBob](https://avatars.discourse-cdn.com/v4/letter/v/839c29/32.png) [@VunderBob](https://boards.straightdope.com/u/VunderBob)\ **Post date:** [December 14, 2006, 8:12pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/19 "2006-12-14T20:12:34Z")
[QUOTE=danceswithcats] There’s always a plastic sheet either held in place by the front doors or some small magnets. Frost & ice form on that instead of the windshield. (Old volly fireman’s trick) 😃 [/QUOTE] I use an old bedsheet for the same reason(s). Also, one morning during last week’s cold snap, I whipped the sheet off the car and saw a wunnerfully clear window. By the time I drove 100 feet to the end of the drive, it had frosted over… :mad: ---
**Author:** ![anomad](https://avatars.discourse-cdn.com/v4/letter/a/9d8465/32.png) [@anomad](https://boards.straightdope.com/u/anomad)\ **Post date:** [December 4, 2013, 12:57pm UTC](https://boards.straightdope.com/t/homemade-windshield-deicer/384078/20 "2013-12-04T12:57:07Z")
My problem is that the defroster does not work. If I use a deicer that refreezes it causes problems. Last year we had several storms and cold temps. I wound up with a can of deicer and the driver side window rolled down and every few minutes I had to stci my hand outside and spray the windshield so I could see to get home. Since I have not had repairs done (lowest quote I had was 1500) and since my contract ends in a week, I need something I can spray on and it will prevent ice formation. The isopropyo alcohol did not work. I bought 70% solution and put it in a spray bottle. It refroze almost immediately. Warm water is a disaster as it melts the ice off initially but freezes up quickly and is worse than the aerosol deicer. I also bought the straight antifreeze, put it in a spray bottle and it was a bit slower but still freezes up again. There must be something that can be put on auto windshields that will not refreeze. [Next page](https://boards.straightdope.com/t/homemade-windshield-deicer/384078.md?page=2)