for glazing aluminum and steel sash either inside or
outside. It should be applied as recommended by the
manufacturer. Metal-sash putty should be painted
within 2 weeks after application, but should be
thoroughly set and hard before painting begins.
There are two grades of metal-sash putty: one for
interior and one for exterior glazing. Both wood-sash
putty and metal-sash putty are known as oleoresinous
caulking compounds. The advantage of these materials
is their low cost; their disadvantages include high
shrinkage, little adhesion, and an exposed life
expectancy of less than 5 years.
Elastic glazing compounds are specially formulated
from selected processed oils and pigments, which
remain plastic and resilient over a longer period than the
common hard putties. Butyl and acrylic compounds are
the most common elastics. Butyl compounds tend to
stain masonry and have a high shrinkage factor.
Acrylic-based materials require heating to 110°F before
application. Some shrinkage occurs during curing. At
high temperatures, these materials sag considerably in
vertical joints. At low temperatures, acrylic-based
materials become hard and brittle. The y are available in
a wide range of colors and have good adhesion qualities.
Polybutane tape is a nondrying mastic, which is
available in extruded ribbon shapes. It has good
adhesion qualities, but should not be used as a substitute
or replacement for spacers. It can be used as a con-
tinuous bed material in conjunction with a polysulfide
sealer compound. This tape must be pressure applied for
Polysulfide-base products are two-part synthetic
rubber compounds based on a polysulfide polymer. The
consistency of these compounds after mixing is similar
to that of a caulking compound. The activator must be
thoroughly mixed with the base compound at the job.
The mixed compound is applied with either a caulking
gun or spatula. The sealing surfaces must be extremely
clean. Surrounding areas of glass should be protected
before glazing. Excess and spilled material must be
removed and the surfaces cleaned promptly. Once
polysulfide elastomer glazing compound has cured, it is
very difficult to remove. Any excess material left on the
surfaces after glazing should be cleaned during the
working time of the material (2 to 3 hours). Toluene and
xylene are good solvents for this purpose.
Rubber compression materials are molded in
various shapes. They are used as continuous gaskets and
as intermittent spacer shims. A weathertight joint
requires that the gasket be compressed at least 15
percent. Preformed materials reduce costs because
careful cleaning of the glass is not necessary, and there
is no waste of material.
MEASURING AND CUTTING GLASS
Always measure the length and width of the opening
in which the glass is to fit at more than one place.
Windows are often not absolutely square. If there is a
difference between two measurements, use the smaller
and then deduct 1/8 inch from the width and length to
allow for expansion and contraction. Otherwise, the
glass may crack with changes of temperature. This is
especially true with steel casement windows.
Cutting glass is a matter of confidence-and
experience. You can gain both by practicing on scrap
glass before trying to cut window glass to size.
Equipment required for glass cutting consists of a glass
cutter, a flat, solid table, a tape measure, and a wood or
metal T-square or straightedge. Look at figure 4-28. You
should lightly oil the cutting wheel (view A) with a thin
machine oil or lubricating fluid. Hold the cutter by
resting your index finger on the flat part of the handle,
as shown in view B.
To cut a piece of glass, lay a straightedge along the
proposed cut, as shown in view C. Hold it down firmly
with one hand and with the glass cutter in the other,
make one continuous smooth stroke along the surface
of the glass with the side of the cutter pressed against
the straightedge (view D). The objective is to score the
glass, not cut through it. You should be able to hear the
cutter bite into the glass as it moves along. Make sure
the cut is continuous and that you have not skipped any
section. Going over a cut is a poor practice as the glass
is sure to break away at that point. Snap the glass
immediately after cutting by placing a pencil or long
dowel under the score line and pressing with your hands
on each side of the cut (view E). Frosted or patterned
glass should be cut on the smooth side. Wire-reinforced
glass can be cut the same as ordinary glass, except that
you will have to separate the wires by flexing the two
pieces up and down until the wire breaks or by cutting
the wires with side-cutting pliers.