Lead came holds the pieces of a traditional stained glass window in a flexible network. It is expected to move slightly, but age, load, heat, corrosion and repeated stress can reduce its ability to support the panel.
Deterioration is a system problem
Cracked lead, open joints and powdery surfaces may be visible, but the complete network and its supports determine the panel’s behavior. One failed joint can be repaired; widespread fatigue may require releading.
The role of cement and support bars
Cement helps weatherproof and stiffen the panel. Support bars and ties help resist movement. When these elements fail together, glass may rattle, bow or crack even when much of the lead still appears intact.
Repair versus releading
The decision depends on how much of the network remains serviceable. Releading is a major intervention, but it can preserve original glass when the existing structure no longer performs reliably.
