Window Sash Restoration and Conservation

As noted in previous blog updates, the Blue Room restoration involves many architecture-related activities. One such activity was addressing the window sashes, which were in need of repair, reglazing (resetting panes) and repainting. The window sashes are the wooden frames that hold the window panes and slide up or down in the larger window frame.

The window sashes were first carefully removed from the window openings and then taken to the architecture laboratory. In their places, temporary sashes were installed. When in the laboratory, each sash was carefully documented using digital photography, paint analysis via microscopy, and visual examination.

Paint analysis results indicated that the sashes did not date to the 18th century, but to the 20th century; these results were consistent with both documentary records and physical evidence. After the analysis and results were completed, the paint was carefully removed using an infrared heating device; this treatment exposed the bare wood, allowing for additional examination and digital photography without a finish.

Each sash received a variety of invasive treatments including:
• Applying consolidants on disintegrating areas (adhesive-like substance that makes damaged areas stable and strong again),
• Rebuilding missing material with architectural epoxies (synthetic filler materials to make the frame whole),
• Replacing and adhering larger parts of the elements (repairing deterioration and reinforcing stability),
• Adding thin strips of wood to each channel edge of the sash frame (to ensure effective functionality and fit in the window openings).

To complete the laboratory work on the sashes, the next step will be to coat the sashes with an alkyd, oil primer; cut replica cylinder glass as needed to replace broken panes; glaze (or reset) each pane with putty; and, paint the exterior sides with two coats of oil paint. The interior sides will be left with only a coat of primer, as they will be painted with replica, hand-ground paint after they are reinstalled in the room and when the rest of the woodwork in the room is painted.