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Historic Structural Glass

Early Manufacture & Use

Historic Installation

Exterior Installation

Interior Installation

Reasons for Damage

Maintenance & Repair

Repair of Cement Joints

Reinstall Glass Panels

Removal of Glass

Replacement of Glass



Exterior Installation

 Essentially, the glass veneer was applied to a dry, smooth, and solid masonry or plaster-on-masonry substrate using an asphaltic masonry adhesive. Manufacturers recommended against affixing the glass directly to wood, either lath or paneling. Glass thicknesses of 11/32 inch or 7/16 inch were most common for commercial storefronts.

 Shelf angles--18-gauge brass or stainless steel, 3 inch square with a 1/2 inch leg fastened directly to the masonry substrate--were used to provide additional support. Inserted along the bottom edge of the panels, they supported every second course of glass and were thus spaced not more than 3 feet apart. Horizontally, the angles were spaced approximately one every 18 inches with at least two used for any piece.

 Actual installation involved applying daubs (2 to 3 inches in diameter) of hot asphalt-based mastic adhesive to the glass and then attaching the glass directly to the substrate. Manufacturers of the mastic recommended coverage of about 50 percent of the glass panels. A full 3 inch width of mastic coverage was recommended around detail edges or any holes in the panels.

The mastic was applied in a molten state after being melted in an electric "hot cup." (Hot cups are still manufactured for this specific purpose and are made to hold enough mastic for a single daub.)



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