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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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