The first step in any repair is . Before touching the glass, determine the type and severity of the damage. Hairline stress cracks (often from sudden temperature shifts) or small star-shaped impact cracks (from a pebble or toy) are excellent candidates for DIY repair. However, if the crack spans the entire width of the pane, if the glass is shattered into multiple pieces, or if it is double-paned (insulated glass unit) with fogging between the layers, replacement is the safer option. For repairable cracks, begin by cleaning the glass thoroughly with a grease-cutting glass cleaner or rubbing alcohol. Use a razor blade to gently scrape away any dirt or debris lodged in the crack. The surface must be pristine for any adhesive to bond correctly. Finally, tape a small marker flag next to the crack to track any expansion overnight; a growing crack signals underlying stress that may require professional help.