Joint repairs should be reversible to enable future repair. Deteriorated wood should be stabilized and strengthened with restoration quality epoxies. Aluminum extruded frames are available that are appropriate for leaded glass windows, and can be a viable option. Purists try to stay away from the use of protective glazing because it detracts from the aesthetics of leaded glass by hiding the intricate reflections and visual interest behind a flat reflection. A well constructed leaded glass window with flexible putty can be relatively thermally efficient on its own.
Vandalism is the most common reason for using protective glazing.
When protection is needed, it is vitally important that it be properly ventilated. In historic or aesthetically important situations, the protective panel can be constructed with leading that follows the main geometric elements, providing a more visually appealing compromise. Acrylic panels provide good protection from accidental breakage or vandalism. Acrylic panels should be installed under skylights as a safety precaution, and building codes may require them. Acrylic exposed to sunlight will become more brittle and less transparent over time.