Carefully chip away the loose or cracked putty using a putty knife. If the old putty is rock-hard, use a to soften it—just be sure to direct the heat away from the glass to avoid cracking the pane. You don't need to remove every speck, but you must clear out enough to create a solid bonding surface for the new material. 2. Clean and Prime the Wood
Raw glazing compound is not waterproof—it needs paint. how to repair cracked window putty
Before you start, assess the damage.