Proper Warming and Cooling Techniques
by Korey Gobin
Most technicians find the need to warm or cool a windshield on a regular
basis. There are many different methods for warming and cooling windshields,
but some have definite advantages over others.
Glass often is not the same as the temperature of the air around it. If
the air temperature is 80° F, but the vehicle is in the shade, the
glass could be 70° F or lower. But, if the vehicle is in the sun,
the glass could be 90° F or higher. For this reason I always recommend
that technicians use a digital thermometer to check the temperature of
the windshield prior to starting a windshield repair.
Rapid heating or cooling of a windshield can cause a volatile break to
crack out, so it’s better to make temperature adjustments slowly and consistently.
It also is important to adjust the temperature of the glass several inches
around the glass, not just at the break itself.
Preferred Heating Methods
These heating methods work well in all but the coldest weather conditions.
When working outdoors in temperatures below freezing, portable heaters
or infrared heat lamps help keep the glass warm during the repair process.
Heat the windshield from the exterior of the vehicle whenever possible.
Heating from the outside requires less heat to achieve the same benefit
and reduces the chance of damaging the glass or laminate.
Following is a list of some common heating tools and their pros and cons.
Moisture evaporators: A moisture evaporator has several benefits.
There’s no need to purchase an additional tool for heating; it can be
used prior to starting a repair and throughout the repair process; it
requires no open flame; it’s very easy to control the area to be heated;
it is usually portable with a 12-volt operation; it is compact in size;
and it can be used from the inside or outside. Moisture evaporators also
have one disadvantage, however—using them makes it difficult to maintain
a consistent temperature throughout the repair process without constant
Hair dryers: One big advantage to using a hair dryer is that it
is inexpensive. It can be used prior to starting a repair and throughout
the repair process; requires no open flame; is very easy to control the
area to be heated; is available in a portable, 12-volt operation; is a
manageable size; and can be used from the inside or outside. As with the
moisture evaporator, it also is difficult to maintain a consistent temperature
when using a hair dryer without constant input from the technician.
Portable heaters: Portable heaters are advantageous because they
provide continuous heat when mounted on an adjustable stand; they can
offer variable temperatures; they heat large areas; and can be used from
the outside. Conversely, the size of portable heaters makes them less
portable; they can be expensive; it’s often difficult to limit the area
that needs to be heated; and they require a 115-volt power source.
Portable infrared heat lamps: Portable infrared heat lamps provide
continuous heat when mounted on an adjustable stand; they offer variable
temperatures, as their distance from the glass can be adjusted; they heat
large areas; and can be used from the outside. Drawbacks, however, are
their size and portability; expense; difficulty in limiting the area to
be heated; and the requirement of a 115-volt power source.
Butane Lighter: Butane lighters are beneficial for two reasons—they
fit easily in a pocket and heat quickly. However, the open flame is a
bit more dangerous than other heating methods; the lighter has to be used
from the inside of the car; and the lighter can leave soot on the glass
that requires cleaning.
Heat Gun: Though a heat gun is not recommended, it can seem to
have some advantages, such as that it heats very quickly; can be used
from the outside; it’s easy to control the area to be heated; it’s manageable
in size; and doesn’t produce an open flame. But, with this one, there’s
a drawback that outweighs all its benefits: with a heat gun, it’s very
easy to overheat the glass and/or the laminate. And, it requires a 115-volt
Torch: A torch is not recommended either, though it shares several
apparent advantages (and disadvantages) with the heat gun—it heats quickly;
can be used from the outside; and is available in a variety of manageable
sizes. However, it also is easy to overheat and damage the glass and/or
the laminate. Likewise, its open flame is more dangerous than other heating
Consult Your Manufacturer
When cooling or heating the glass, technicians should always refer to
their manufacturers’ recommendations and guidelines for achieving the
Korey Gobin is an account executive with Delta Kits in Eugene,
Ore. Mr. Gobin’s opinions are solely his own and not necessarily those
of this magazine.
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No reproduction of any type without expressed written permission.