Can an auto glass repair man stop your cracked windshield from spreading?

In some cases, yes. If the damage to your windshield is minor, an auto glass repair technician can stop it from spreading by injecting a clear resin into the cracks and curing it with ultraviolet light. This will help to bond the glass together and prevent the damage from getting worse. However, if the damage is severe, it is likely that the windshield will need to be replaced.