The method we use is kind of like what your dentist does, make it look worse before we can make it look better. We drill a small hole to get underneath the surface of the glass, then we open the break by tapping it open. Then we fill it with a resin that is UV activated and then cured. A second coat is applied, cured again, then the excess is scraped away and a polish is applied to minimize the appearance of the repair. Then the glass is cleaned and you're ready to go.
On a crack repair, we drill a small hole at the end to stop it from spreading. Then it is filled three inches at a time and tabbed so as not to lose what we have repaired. During this process, the vehicle must remain as still as possible. Leaning or sitting in the vehicle will cause the glass to twist and allow air to be drawn into the repair. After the entire break is filled, it is also cured, polished and cleaned in the same manner as above.
We use the full cut method, which is suggested by the National Glass Association. What that means is the old urethane is cut down to approximately 1/32 to the original thickness. Then a new bead of urethane is applied and the glass re-installed. All necessary moldings and trim are removed so as not to be damaged during installation. We take the utmost care to do a proper installation. Your windshield does more than keep the rain off of you. It is designed to keep you in the vehicle in the unlikely event you're in a frontal collision and to help support the roof in a rollover. So we do everything we can to be sure your windshield is installed correctly and safely.