Barrett Smith, President of Auto Damage Experts wrote: “This is why it is so very import to be very careful and selective when choosing a sublet glass replacement company and other outside vendors to provide services for your business. Just because you engage another’s service doesn’t exempt you and your company from liabilities that may arise from a tragic loss such as this. Even recommending another service could land you in enough trouble to cost you tens of thousands in dollars proving you have no liability!”
Let’s take a look at the basics of glass and windshields in particular.
1) What is the function of a windshield?
The main function of today’s windshield is
■ It is part of the vehicle structure
■ It is part of the frontal air bag system
■ It restrains the passengers in vehicle
■ And yes, it keeps the bugs off your face.
One reason rollovers are so dangerous is that, when a vehicle rolls over, its roof can crush down on the occupants, causing head injuries, paraplegia and death. Today’s vehicles are engineered so that the windshield provides much of the stiffness necessary to keep the roof from collapsing. In fact, some experts say that the windshield accounts for up to 60% of the cabin’s structural integrity in a rollover.
Some vehicles, the passenger’s side frontal air bag is deflected off of the windshield and is aimed at the front passenger seat. Just these two examples should serve to remind us that installing a windshield takes more than a phone call to your local vendor and you are finished. Not by a long shot.
2) Before going any further, let’s look at how glass is categorized.
All windshields are marked with two letters: AS stands for American Standard. The number indicates the position in the vehicle where the glass may be used, based on its optical quality. AS1 is the clearest glass (at least 70% light transmission), is laminated, and can be used anywhere in a motor vehicle (typically just the windshield).
AS2 is tempered, with at least 70% light transmission, and can be used anywhere except the windshield, and—
AS3 can be used in certain locations in certain vehicles (it can be laminated or tempered, and has less than 70% light transmission.) AS3 is also known as Privacy Glass.”
We deal with 2 types of glass: laminated and tempered.
Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral (PVB), between its two or more layers of glass. The bonding process takes place under heat and pressure. When laminated under these conditions, the PVB interlayer becomes optically clear and binds the two panes of glass together. Once sealed together, the glass “sandwich” (i.e., laminate) behaves as a single unit and looks like any other glass.
Tempered glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering creates balanced internal stresses which cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards.
These two pictures and examples of the marking on the glass. They are known as “bugs” and will be found on all automotive glass and to identify what type of glass it is.
Vehicle manufacturers must meet Federal Motor Safety Standards 208, 212, 216 & 219 for glass and vehicle occupant safety. Aftermarket installers use urethane and primers that are manufactured and tested to meet federal and industry standards, but they are not regulated by the government, which means that you better do your due diligence when subletting your glass. (See form on page 56.) If you are not familiar with the safety standards here they are:
FMVSS and Autoglass
FMVSS205, FMVSS212, FMVSS216, FMVSS219
See below for a look at a few of the popular Federal Motor Vehicle Safety Standards pertaining to auto glass, including a brief summary of each standard.
571.205 Standard No. 205; Glazing Materials
Scope. This standard specifies requirements for glazing materials for use in motor vehicles and motor vehicle equipment.
Purpose. The purpose of this standard is to reduce injuries resulting from impact to glazing surfaces, to ensure a necessary degree of transparency in motor vehicle windows for driver visibility, and to minimize the possibility of occupants being thrown through the vehicle windows in collisions.
571.212 Standard No. 212; Windshield Mounting
Scope. This standard establishes windshield retention requirements for motor vehicles during crashes.
Purpose. The purpose of this standard is to reduce crash injuries and fatalities by providing for retention of the vehicle windshield during a crash, thereby utilizing fully the penetration-resistance and injury-avoidance properties of the windshield glazing material and preventing the ejection of occupants from the vehicle.
571.216 Standard No. 216; Roof Crush Resistance
Scope. This standard establishes strength requirements for the passenger compartment roof.
Purpose. The purpose of this standard is to reduce deaths and injuries due to the crushing of the roof into the occupant compartment in rollover crashes.
571.219 Standard No. 219; Windshield Zone Intrusion
Scope. This standard specifies limits for the displacement into the wind-shield area of motor vehicle components during a crash.
Purpose. The purpose of this standard is to reduce crash injuries and fatalities that result from occupants contacting vehicle components displaced near or through the windshield.
Do you know what the black strip in the photo is called and what’s it for?
It’s called a Frit and it serves two roles on the glass. First, as a cosmetic feature that is used to hide interior trim and pinchweld details. Second, the frit inhibits UV degradation of urethane adhesives. While the frit will not completely block the UV rays from passing through the glass, it does significantly reduce UV light transmission. Most urethanes are not UV stable. If urethane is left exposed to sunlight for prolonged periods of time, it will yellow and turn chalky. Presence of the frit will extend the lifetime of the urethane adhesive system.
Many of today’s vehicles have been specifically designed to utilize the windshield as a structural component of the vehicle body by providing increased torsional stiffness. Vehicle manufacturers are careful to select special, high-modulus polyurethane (PUR) adhesives to bond the windshield to these specific vehicles. Relying on the windshield as a structural member, the high-modulus adhesive also allows the OEM to minimize the thickness of the steel used to build the car, thus reducing weight and costs. The high modulus urethane is more rigid when completely cured, and the properties of the non conductive urethane do not interfere with the newer sophisticated electronics in vehicles.
Each urethane has its unique set of primers which are an integral part of the bonding process. Each urethane also has a cure time (the time that it takes for the urethane to harden) before it is safe to drive the vehicle. It is important for the collision repair facility to know what that cure time is. If the urethane is not cured, the safety of the vehicle will not have been restored.
The pinch weld that has been repaired or replaced, needs am epoxy primer or a similar product applied to the bare metal surface. Some vehicle manufacturers allow refinishing the surface, while others want only epoxy primer applied. All OEMs state that there should be no body filler applied to the pinchweld where urethane is used due the fact that the urethane will not adhere to the substrate. Let’s take a quick look at adhesion failure.
Adhesive failure: The inability of an adhesive to stick to a surface. During adhesive failure, the adhesive cannot bind two surfaces together and separates from the substrate.
Cohesive failure: The inability of an adhesive to resist internal separation. During cohesive failure, the adhesive sticks to both surfaces, but can not hold them together.
Many windshields and backlites have antennas and defroster grids embedded in the glass. A non-conductive adhesive should be used if the adhesive will contact the antenna or defroster lines when the part is installed. Non-conductive adhesives prevent interference with antenna systems and heated defroster systems that are contained in the glass. Many new glass parts have the antenna, defroster connections or buss bars around the edge of the glass in the same area that the adhesive is applied to install a glass part. Using a conductive adhesive will affect the performance of the electrical system. Several adhesive manufacturers offer a non-conductive product for these glass applications.
A broken heated grid line on a backlite will affect the operation of the antenna. Many new radio and cellular phone antenna designs are incorporated into the heated grid design in the backlite. If a heated grid line is broken it will affect the performance of the antenna. The line break will become more noticeable with the general public as diversity antennas gain popularity and reduce the need for traditional mast antennas. There are aftermarket grid line repair systems available which can restore both the heating and the antenna characteristics of the grid line.
Does the rain sensor module come on the replacement windshield? No. At this time, none of the rain sensor designs require the sensor to be applied by the manufacturer on the replacement windshields. The electronic sensor that is on the existing windshield in the car must be removed and re-mounted onto the replacement windshield.
How is the rain sensor attached to the replacement windshield? There are special re-attachment kits for the replacement industry, available through your local dealer, which can be used to re-attach the electronic rain sensor to the new windshield. The Cadillac kit consists of tape, cleaners and primers for replacing the Cadillac module. The Mercedes/BMW kit contains the tape and a new lens. Instructions for application are included in all the kits.
Encapsulated Glass has the molding permanently attached to the glass. Most of the time when the glass is removed, the molding is damaged and a new glass and molding is necessary.