Proper Warming and Cooling Techniques

Unless you live in Hawaii or some other similar tropical paradise where the weather is relatively consistent, you will probably 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 temperature is often not the same as the temperature of the air around it. If the air temperature is 80º but the vehicle is in the shade, the glass could be 70º F or lower, but if the vehicle is in the sun, the glass could be 90º 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 is also important to adjust the temperature of the glass several inches around the glass, not just at the break itself.

Preferred heating method: Prior to beginning the repair, preheat a Delta Kits moisture evaporator for 30 seconds, place about ¼” off the glass over the impact point of the break on the outside of the vehicle, and slowly rotate in a circular motion, widening the circles with each rotation until the glass temperature in an area of at least 3” around the break reaches 80º F to 100º F*. After attaching the bridge assembly and beginning the injection process resume heating around the injector as necessary to maintain a minimum temperature of 80º F. Remember to always keep the moisture evaporator moving during the heating process. A hair dryer works nearly as well as the moisture evaporator for warming the glass, and is used the same except that it should be held about 2” from the glass during the heating process.

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 are recommended to 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.

Do not heat the glass to over 100º F* and always make sure the resin temperature is within 10º F of the glass temperature. Cold resin on hot glass or vise versa may make the damage spread.

Below is a list of the pros and cons of some common heating tools.

1) Moisture evaporators.

a. Pros

i. No need to purchase an additional tool for heating.
ii. Can be used prior to starting a repair and throughout the repair process.
iii. No open flame.
iv. Very easy to control the area to be heated.
v. Portable 12V operation.
vi. Compact size.
vii. Available from windshield repair suppliers.
viii. Can be used from the inside or the outside.

b. Cons

i. Difficult to keep a consistent temperature throughout the repair process without constant input from the technician.

a. Pros

i. Inexpensive.
ii. Can be used prior to starting a repair and throughout the repair process.
iii. No open flame.
iv. Very easy to control the area to be heated.
v. Available in portable 12V operation.
vi. Manageable size.
vii. Can be used from the inside or the outside.

b. Cons

i. Difficult to keep a consistent temperature throughout the repair process without constant input from the technician.

a. Pros

i. Continuous heat when mounted on an adjustable stand.
ii. Variable temperature.
iii. Heat larger areas.
iv. Can be used from the outside.

b. Cons

i. Size and portability.
ii. Expense.
iii. Difficult to limit area to be heated.
iv. Require 115V power source.

a. Pros

i. Continuous heat when mounted on an adjustable stand.
ii. Variable temperature (by adjusting distance to glass.
iii. Heat larger areas.
iv. Can be used from the outside.

b. Cons

i. Size and portability.
ii. Expense.
iii. Difficult to limit area to be heated.
iv. Require 115V power source.

a. Pros

i. Fits in a pocket.
ii. Heats quickly.

b. Cons

i. Open flame is more dangerous than other heating methods.
ii. Has to be used from the inside.
iii. Can leave soot on the glass that requires cleaning.

a. Pros

i. Heats very quickly.
ii. Can be used from the outside.
iii. Easy to control area to be heated.
iv. Manageable size.
v. No open flame.

b. Cons

i. Easy to overheat glass and/or laminate.
ii. Require 115V power source.

a. Pros

i. Heats very quickly.
ii. Can be used from the outside.
iii. Available in a variety of manageable sizes.

b. Cons

i. Very easy to overheat and damage glass and/or laminate.
ii. Open flame is more dangerous than other heating methods.

-Brent Deines