Unless they're trying to commit insurance fraud, no one decides one day to destroy their windshield. However, this is exactly what happens on many winter mornings when people are running late for work (or appointments) and try to remove the ice from their car windshields using the following two questionable methods.
Pouring Hot Water on Frozen Glass
When people want to melt something fast, the first thing they think to do is pour hot water on it (or submerge it in a hot water bath). Thus, it would seem like common sense to use this method to eliminate ice on a vehicle's windshield. However, in their haste to get the job done, people forget the basic laws of thermodynamics.
Heat makes things expand, while cold makes them contract, and pitting opposing forces (in this case extreme temperatures on either end) against each is a recipe for disaster. Specifically, when you pour hot water on a cold windshield, the glass contracts to adjust to the sudden shift, which often results in cracks forming on the windshield. Bonus points if your windshield is already damaged, because the weakened glass may actually shatter when you throw hot water on it.
Although you may be in a rush, don't pour hot water on your icy windshield. Additionally, don't use a hair dryer or other heated instruments to defrost the glass besides your vehicle's internal defrosting system. If you're in rush to clear your windshield, use a deicer instead. While you can purchase this product from a store, you can also make your own at home by combining a 1/3 cup of regular temperature water with 2/3 cup of rubbing alcohol. Apply liberally and turn on your wipers.
Using Metal Scrapers to Remove Ice
Scraping ice off the windshield using a plastic scraper is a tried and true method of clearing the glass. However, it's not unusual for people who can't find their plastic scrapers (or don't have one at all) to use alternative tools to physically remove the ice, and sometimes these tools are made of metal (e.g. putty knife or their key).
This is a pretty terrible method of ice removal, because the metal can actually scratch the glass. While one or two small scratches may not be too bad, several gouges right in the prime viewing area can make it hard to see clearly and lead to problems on the road.
If you don't have a regular scraper, you can use an alternative tool. Just make sure it's made from plastic. For instance, credit cards can be a good alternative as can thick ID badges. It may take longer to remove the ice, but you won't have to pay to get problematic scratches repaired if you use a dangerous substitute.
For more tips on quickly removing ice from your windshield or to have a damaged windshield repaired, contact a local glass repair company. Visit a site like http://unitedglassaurora.com/ for more help.