If your car's windshield was chipped today, and you want to have it repaired rather than replaced, then the following tips will help keep it from cracking until you can get it into your local windshield replacement shop.
Tip: Gently Clean the Chipped Area
As soon as you notice the chipped area on your windshield, wash the chipped area with some room-temperature water, and dry it thoroughly.
Tip: Apply a Piece of Clear Tape Over the Chip
Once the chipped area has completely dried, apply a piece of clear shipping or packing tape over it. The purpose of the tape isn't to hold the glass together or prevent further cracking, it is simply to keep dirt out of the chip so it can be cleanly repaired.
It is important to note that this is one time when duct tape isn't the solution to a problem. If you put duct tape over the crack, then it's gooey adhesive will seep down into the crack and cause problems when the auto glass repair shop attempts to repair it.
Tip: Avoid Actions that Lead to Cracking
When your car's windshield is chipped, you need to avoid taking actions that can make it send out cracks. If the windshield cracks, then you won't be able to have it repaired, and instead, will need an expensive windshield replacement.
Actions that lead to further cracking include:
driving on bumpy roads
driving over a pothole
slamming a car door
slamming the car's trunk
While you shouldn't do a lot of driving before you get your windshield fixed, avoiding jarring actions will help preserve its integrity if you must drive it.
Tip: Avoid the Heating and Cooling Cycle
In addition to avoiding driving situations that will lead to additional cracking, you also should avoid excessively heating and cooling your windshield. For example, if you park your car in the sun all day and then get in and turn on your air conditioner, the glass will go from hot to cold quickly, and this will lead to cracking. Instead of parking in the sun, choose a spot that is protected from direct sunlight, and don't use the air conditioner if the glass feels warm when you touch it.
Finally, if you chip your windshield in the dead of winter, you should avoid using the defroster or heater for the same reason as above – it will cause the windshield to crack from the quick change in temperature.