To repair a mobile windscreen or a cracked windshield, inject resin or adhesive into the crack. Make sure the windscreen's surface is dry before injecting the adhesive and, once the adhesive hardens, smooth any rough spots with a razor blade.
It is important to repair the crack quickly so that dirt and moisture do not clog the crack and cause further problems. Dry the windscreen completely and then apply the adhesive using a syringe. Hold the syringe in place at the location of the crack for a full minute to create a vacuum and ensure that adhesive materials reach deep into the crack. Then, remove the adhesive sheet and let the adhesive dry completely. When the adhesive is dry, use a single stroke of a sharp razor blade to cut any protruding spots from the glass and create a smooth appearance.
After finishing the windscreen repairs, do not drive the vehicle for a few hours. This gives the injected resin time to dry and harden. The amount of time to wait before driving the vehicle ranges from three to 24 hours, depending on the type of resin used to repair the crack.
Some retailers sell kits that contain the items needed to repair a cracked windscreen. Before beginning a windscreen repair, make sure the crack is the kind that a repair fixes completely. If the chip is too big or if it is too close to the edge of the windscreen, replace the entire windscreen rather than attempting to fix the crack. Trying to fix a crack that is too large destabilizes the windscreen and creates a safety hazard.