Windshields are made of three parts: one clear vinyl laminate sheet sandwiched between two pieces of glass pressed together and heated to make our modern windshields. In 1904 the first windshields were made of single sheet glass, but was quickly discovered how dangerous single pane glass can be in an accident. After several law suits, auto makers needed to find a stronger safer auto windshield. This is what led to the construction of our modern laminated windshields, these windshields are safer, stronger resist chipping and cracking due to rocks and other debris sticking on our windshields, and when struck by large objects that shatter the windshield the vinyl laminate holds the broken glass together. When a windshield gets rock chipped there are almost always cracks associated with these breaks, these cracks may not be seen with the naked eye but they are there.
Its glasses nature to crack when impacted, but not all breaks are the same, there are star breaks bull's-eyes, bird wing or combination breaks and cracks. Some will crack out upon impact and others can crack out within minutes of impact, and some may not crack out for years, why you ask? Simple the law of physics, the expansion and contraction through thermal conduction on sunny days and cool nights constantly shifts the broken or chipped auto glass this movement is what causes further cracking. Water and dirt can enter the break, then when the water freezes it expands this will cause chips to crack and cracks to expand, dirt on the other hand you can't hide and will always be visible in the repaired area. While internal stresses from manufacturing and installation are different on every windshield, most all windshields have some inherent stresses applied. This is why some windshields crack immediately after an impact and other windshields crack out over time.
This can be an expensive experiment, waiting to see if the crack starts to spread before repairing, because almost all rock chips and cracks will expand and when they do most will crack out eliminating repair as an option to replacement. You don't want to play this game as repair is much less expensive than auto glass replacement. Some windshields replacements will cost over $700.00 compared to $40.00 to$70.00 for repair. While some will choose to experiment with this option, others will see whats coming and choose timely repair and save big time.
When a windshield is cracked or chipped the structural integrity is impaired and depending on things like the severity of the break the location of the break, and applied stresses to the glass. These factors determine the level of integrity loss, but for safety reasons any structural integrity loss of the windshield glass is unacceptable, period. You and your family are behind that glass, safety is first always! What should you do if you get a rock chip or small crack? Cover rock chips or cracks that are not in your direct line of sight with clear tape as soon as possible to prevent contaminates like oil, dirt or moisture from entering the break causing expansion and further cracking and avoiding expensive windshield replacement. Then call a windshield chip and crack repair technician for repair as soon as you can don't be the one testing your luck with that chipped or cracked windshield.
