There are several reasons for adjusting the temperature of the glass before and during the repair process. Some are standard, some are debated. Also, there are ways to do it and not to do it!
First, lets talk about glass temperature before you begin the process. There is a lot of science dealing with the effect of temperature and rate of change in temperature on laminated glass both broken and unbroken. In order to keep it simple, we like to say that if you are comfortable, the glass is "comfortable." Repairs should never be performed if the glass is too hot or too cold to touch! The chances of you increasing the amount of damage and causing a crack to "run" are very high. Instead, take the time to bring the temperature into a more acceptable range gradually.
Obviously, the best conditions are in an indoor environment between 60 and 90 degrees Fahrenheit. However, you can also move the car into the shade and open the doors until the glass cools if it is too hot. If it is too cold and you can't get indoors, we suggest not performing the repair until conditions change. We do not recommend the use of hair dryers, heat guns or torches to warm the glass at this extreme level. The quick temperature change is one of the main reasons rock chips turn into long cracks. If you monitor the process closely by touch, you can use the defrosters to change the glass temperature. However, USE CAUTION, take your time and do not use extreme settings. Many a customer either neglects to have a chip fixed or is unaware of it. The first cold morning of the year comes and he puts his defrosters on high to warm the car quickly. He goes inside for some coffee while he waits and comes out to a crack across the entire glass!
In the end keep the following points in mind:
- Excess heat and quickly induced heat are the main contributors to glass instability.
- There is a large window of acceptable temperature range in which you can safely perform repairs. Just make sure you get the glass there gradually.
- Our Crack Filler is designed to flow at very low temperatures. So, utilize the Resin properties and give it time, rather than heating the glass and causing a "run."
- During extreme conditions try to have your Resins within ten degrees of the glass temperature.
- If you feel the conditions are "on the cusp" of what is an acceptable range, avoid using the Additional Pressure (AP) notches on the Plunger. Allowing more time and repeating the vacuum/pressure steps is a safer alternative.
Now, let's say you have the entire glass in an acceptable range before you start the repair process. Regardless of whether technicians use or system or our competitor's, there are some that use additional heat when performing the process. This technique has been greatly debated, so we will give our take on the subject.
- It is always best to use the proper Resins and techniques for the particular break style rather than use heat in any way.
- There is a chance that heating an area can cause a break to "run."
- Heat can expand the glass and actually close the crack, make it appear filled and prevent Resin from flowing into the crack.
- Alternatives to heat are Flexing and Priming the break. This is discussed elsewhere.
- Warm air can be used to remove moisture from a break before starting the process. We suggest never using an open flame inside or around a vehicle. Furthermore, a hair dryer is optimal on the outside of the vehicle to dry a break. However, we do understand that many Auto Glass Techs have heat guns and are adept enough with them not to over heat the area. Just use caution and if you are inexperienced, use the hair dryer. Also, LET THE GLASS COOL BEFORE YOU START THE PROCESS!
- One grey area. If you happen to choose a Resin with to high of viscosity for the application, heat will allow it to flow better. However, judgement must be used as to how much heat is needed and to what degree is it really helping flow rather than closing the break.
- Does additional heat have effects on the repair process? Yes. We will even admit that there may be times when added heat may result in a better repair. There are many factors at play and every break is different in structure. (In fact, there is no way we can say, if you have exhausted every possible technique, and you still see and air pocket that just will not fill, that you should not try a touch of heat. Just the random changes could help the resin flow. Just allow it to cool before curing.) However, 99% of the time, we feel that apart from moisture removal, additional heat is NOT required for optimal results with our system! Use the right Resins for the right job and follow the procedures and your repairs will be remarkable!