Advancements in automotive glass technology are evolving quickly, along with most other aspects of modern automotive development. In the same way that passenger retention systems have advanced from just lap belts to shoulder belts along with air bags and braking systems have advanced to using anti-lock technology and stability control, auto glass retention systems have advanced.
As technology progressed in auto glass retention systems from rubber gasket and butyl retention seals to adhesive bonding, the safety and integrity of the safety glass in automotive accidents improved dramatically.
The use of adhesives to retain automotive safety glass has greatly necessitated advanced education and adoption of safety standards when replacing auto glass.
The Auto Glass Safety Council has produced the American National Standard Automotive Glass Replacement Safety Standard (AGRSS) working under the auspices of the American National Standards Institute (ANSI). This standard represents the best practices for the replacement of auto glass to insure the integrity and safety equivalent to or better than the original factory installation. 1
The public needs to be aware that the replacement of auto glass has become a technical procedure requiring trained technicians using appropriate materials in order to achieve a safe and lasting result that will not cause risk to the occupants or damage to the vehicle.
Proper preparation of the new glass to be installed is necessary in the same way that the proper preparation of a surface to be painted must be done in order for the paint to adhere properly. All contamination must be removed from the glass and the proper primer or activator must be applied according to the adhesive manufacturer’s specifications.
The glass to be replaced needs to be removed from the vehicle body, taking as much care as possible as to not damage the mating surface of the adhesive on the body. There are different tools and techniques that can be used to cut the adhesive. Any scratches in the body need to be addressed with an approved primer that is part of the adhesive system used, in order to prevent rust that will not only damage the vehicle but also put at risk the integrity and safety of the vehicle. Any corrosion encountered when replacing the glass must be addressed. If the corrosion cannot be sufficiently repaired by the technician, it needs to be repaired by a qualified auto body repair facility.
The adhesive used to adhere the glass to the body must be a part of an approved retention system as noted in the AGRSS standard. The adhesive and related primers and activators must be used before their expiration dates. Lot numbers and expiration dates should be recorded.2
Environmental conditions must also be taken into consideration when using adhesives to bond auto glass. All manufacture specifications need to be strictly followed regarding temperature and humidity. Not doing so can compromise the adhesion of the glass. 3
Adhesive cure times vary by manufacturer, product and environmental conditions. Because these cure rates vary, the technician must be aware of the Safe Drive Away Time (SDAT) of the system used under the conditions in which it is used.4 This is vital from a safety standpoint. If a vehicle is released to be driven before the SDAT and the adhesive has not had appropriate cure time, the occupants will not be properly protected in the event of a collision. The air bag, if deployed against a windshield that is not adhered properly to the body, be it because of inappropriate cure time or improper installation, will not perform properly to protect the occupants. This is also critical in the event of a vehicle rollover. Properly adhered auto glass is a structural part of the passenger compartment, helping to support the roof. Protection from a collapsing roof in a roll over is dependent upon a proper glass replacement installation.
Additional considerations must be taken when the adhesive is not contacting the glass directly but instead adhering to a metal or plastic frame such as on a truck back glass assembly (slider) or bonded quarter or vent glass. The technician must be aware of the proper preparation of these surfaces and use of proper primers and adhesive products.
Although the above information is by no means a total dissertation on the proper installation of auto glass with a bonding adhesive, it does point out not only the necessary education and knowledge for the proper installation but the willingness by the persons installing the replacement glass to follow the guidelines and not take “short cuts”. Not following the proper procedures to replace auto glass can result in at the very least damage to your vehicle because of rust and or leaks but more importantly can result in personal injury to anyone who is an occupant during an accident.
A qualified auto glass facility and its staff and technicians should welcome inquiries about their qualifications and procedures that they have in place to safely replace a glass in your vehicle. A properly trained and qualified staff will be proud to reassure you of their credentials. If your questions are not satisfactorily answered you may want to consider another facility to be confident that your safety and your investment remain intact.
2 ANSI/AGSC/AGRSS 003-2015 AUTO GLASS SAFETY COUNCIL (SECTION 5)
3 ANSI/AGSC/AGRSS 003-2015 AUTO GLASS SAFETY COUNCIL (SECTION 6.1)
4 What is Safe Drive Away Time, SIKA Corporation U.S.