Don’t paint the putty too soon—it traps solvents and leads to future cracking.

Roll the putty into a thin rope (about ¼–⅜ inch thick) and press it firmly into the gap between the glass and frame. Smooth it with a putty knife at a 45° angle, matching the profile of the old putty.

Traditional oil-based glazing compound (like DAP '33') or modern hybrid polymer alternatives . 2. Removing the Old, Cracked Putty

Roll a small amount of glazing putty in your hands until it’s soft and pliable. (If it’s too stiff, a few drops of linseed oil can help.)

Noticed cracked, crumbling, or missing putty around your windowpanes? Don’t panic—and don’t call a glazier just yet. Fixing cracked window putty (also called glazing compound) is a simple weekend project that can improve energy efficiency and prevent moisture damage.

Apply exterior paint over the cured putty, overlapping slightly onto the glass for a waterproof seal.