For drivers in the northern latitudes, ice buildup is more than just a seasonal inconvenience. Ice can easily build to more than an inch thick around the base of your windshield, side windows, hood and trunk lid. Not only are such sheets of ice difficult to remove, doing so incorrectly can damage your glass and paint. Airports use special deicing fluids to remove such buildup from airplane wings and to prevent further icing while the airplane cruises at high altitudes. Similar deicers are commonly available at auto parts stores, but you can easily make your own with a few inexpensive household chemicals.
Combine a 60/40 mixture of propylene-glycol-based (PG) antifreeze and water in a spray bottle. You can use a standard ethylene-glycol-based (EG) antifreeze, but PG antifreeze is far less toxic to people and animals. Propelene glycol is an organic alcohol compound that dissolves the hydrogen bonds that hold the ice crystals together. Standard rubbing alcohol will dissolve ice as well, but PG works better and lasts longer.
Add standard dish soap to the mixture at a 10-to-1 ratio. If you have 10 ounces of water/antifreeze, add 1 ounce of dish detergent. Dish detergent is a surfactant, meaning that it lowers the surface tension of any fluid it touches. Lowering the surface tension will allow the melted ice to more easily slough off the windows.
Allow the soap/antifreeze/water solution to sit in your home at night. The warmer the mixture is the quicker it will work, but it shouldn't be any warmer than about 80 degrees or you risk cracking the freezing-cold glass through thermal shock.
