Windscreen are often chipped by stone or other objects launched. At the contact with the glass, these objects can create different damage of different sizes. These damages can totally compromise a windshield or any other auto window and they have to be replaced if the damage is not fixed in time. Usually, in approximately 70-80% of the cases these chips are small, from 3-5 millimeters to 25-30 mm. These cracks can be fixed safely and with a minimum cost, without removing the window, regaining the integrity and visibility of the glass and stopping the damage to compromise the windscreen.
Repair is done by injecting on the damaged area a special resin, actually a "fluid glass". This resin, injected with high pressure with the help of a special device fills out the cavity created by the foreign element and stops the extension of the crack or chip.
It is hard to understand how a crack or chip can be repaired without knowing and understanding how auto glass is built. In the automotive industry two types of glass are used: laminated glass , used at the windshields and secure glass used at the side and rear windows. Laminated glass has two layers of glass and between these two layer there is another layer, a film called poli-vinil-butiral, all pressed together like a sandwich.
When an object hits the windshield with high speed, the exterior layer of the laminated glass cracks, but thanks to the vinil which absorbs most of the impact . Otherwise this impact would shatter the glass, but this way it is limited and localized. Usually a the chip has a round or star shape with a diameter between 5 and 25 mm. The chip on the glass is in fact a cavity filled with air, created by the shockwave of the impact.
The main objective of glass repair is to remake the integrity of the glass layer and to stop for good the extension of the damage. Also, glass repair dramatically improves the optics of the window. After filling out the cavity with the special resin, the area is polished. After finishing the hole process, which takes up to a couple of hours (it has to dry!) the chip disappears almost totally. If the chip or crack is old and was "contaminated" with dirty water , after repairing the damage the damaged area will be more dark-colored, but all this will pass unnoticeable.