Figure 4-30.-Types of metal-sash glazing.
nonporous surface. Figure 4-30 shows examples of the
types of metal-sash putty. Elastic glazing compounds
may be used in place of putty. These compounds are
produced from processed oils and pigments and will
remain plastic and resilient over a longer period than
will putty. A skin quickly forms over the outside of the
compound after it is placed, while the interior remains
soft. This type of glazing compound is used in windows
or doors subject to twisting or vibration. It may be
painted as soon as the surface has formed.
For large panes of glass, setting blocks may be
placed between the glass edges and the frame to
maintain proper spacing of the glass in the openings. The
blocks may be of wood, lead, neoprene, or some flexible
material. For large openings, flexible shims must be set
between the face of the glass and the glazing channel to
allow for movement. Plastics and heat-absorbing or
reflective glass require more clearance to allow for
greater expansion. The shims may be in the form of a
continuous tape of a butyl-rubber-based compound,
which has been extruded into soft, tacky, ready-to-use
tape that adheres to any clean, dry surface. The tape is
applied to the frame and the glass-holding stop before
the glass is placed in a frame. Under compression, the
tape also serves as a sealant.
Glass may be held in place in the frame by spring
clips inserted in holes in the metal frame or by
continuous angles or stops attached to the frame with
screws or snap-on spring clips. The frames of metal
windows are shaped either for outside or inside glazing.
SETTING GLASS IN WOOD
AND METAL SASHES
Do not glaze or reglaze exterior sash when the
temperature is 40°F or lower unless absolutely
necessary. Sash and door members must be thoroughly
cleaned of dust with a brush or cloth dampened with
turpentine or mineral spirits. Lay a continuous
1/6-inch-thick bed of putty or compound in the putty run
(fig. 4-31). The glazed face of the sash can be
recognized as the size on which the glass was cut. If the
glass has a bowed surface, it should be set with the
concave side in. Wire glass is set with the twist vertical.
Press the glass firmly into place so that the bed putty
will fill all irregularities.
When glazing wood sash, insert two glaziers points
per side for small lights and about 8 inches apart on all
sides for large lights. When glazing metal sash, use wire
clips or metal glazing beads.
After the glass has been bedded, lay a continuous
bead of putty against the perimeter of the glass-face
putty run. Press the putty with a putty knife or glazing
tool with sufficient pressure to ensure its complete
adhesion to the glass and sash. Finish with full, smooth,
accurately formed bevels with clean-cut miters. Trim up