Definitions

• Autoglazier: an individual who removes, replaces and installs automotive window glass
• Auto glass technician: an individual who fixes all forms of automotive glass chips and cracks 
• Ceramic frit: ceramic ink applied to direct glazed automotive glass that provides protection from ultraviolet radiation
• Curing: the progressive hardening of a material by chemical reaction
• Dam: self-adhesive foam strip placed on the vehicle's aperture to maintain the distance of the windscreen from the vehicle's body while the direct glazing adhesive cures and prevents the direct glazing adhesive getting into the interior of the vehicle
• Direct glazing: the securing and sealing of glass in a prepared opening in a vehicle using an appropriate direct glazing adhesive system
• Flash-off time: the time taken for the solvent to evaporate from a solution after it has been spread on a surface
• Pinchweld: the flange formed by joining of two or more body panels
• Dull spot: the small area of the windscreen present after a repair 
• Laminated safety glass: consists of two or more sheets of glass held together by one or more layers of plastic material ‘interlayers’

Glass Replacement

The structural integrity, safety and appearance of the vehicle must not be compromised when automotive glass is replaced. The following provides general industry guidelines and advice for the safe replacement of automotive glass.

The AGA acknowledges that every vehicle and job is unique and will require a tailored approach. These general industry guidelines reference the following:

• AS4739:2017 Direct Glazed Automotive Glass Replacement – Light Vehicles 
• AS/NZS 2080 -2006 Safety glazing for land vehicles
• ADR Australian Design Rules for Motor Vehicles and Trailers
• FMVSS212 Federal Motor Vehicle Safety Standard 212 – Windshield Mounting
• Euro-NCAP European Crash Test Standard

For more specific advice please contact the members listed in the member search and purchase the relevant standard/s listed above.

 
Safety

• Carry out a vehicle inspection and fit the appropriate protection wherever necessary
• Adhere to the manufacturer's material safety data sheets for each chemical

Preparing the vehicle

• Fit seat and trim protectors, and bonnet and/or roof covers
• Match the correct replacement windscreen to the vehicle
• Remove mouldings, trims, wipers and any other necessary components 
• Remove from around the aperture any items affixed to the glass that are to be reused
• Remove dirt, dust or debris
• Disconnect electrical connections

Removing the glass

a. Cut through the original adhesive bond using an appropriate cutting tool
b. Protect the vehicle when cutting close to the trim or dash pad (see Figure 1)
c. If necessary, apply protective tape to prevent damage to the paint work
d. Remove the glass from the aperture

Preparing the aperture

• If required, trim the remaining adhesive to a suitable thickness to allow the glass to fit properly
• Remove loose sections of existing adhesive and clean the aperture to remove any dirt and debris. Take care not to damage the paint work
• Trial the glass in the aperture and check for conformity to size and shape
• Ensure the body primer is ready for applications as recommended by the manufacturer
• Using a dauber or other suitable applicator, apply an even, uniform coat of primer to the aperture, making sure scratches on the paint on the aperture are adequately primed to reduce the likelihood of corrosion forming 
• Perform any preliminary surface preparation specified by the direct glazing adhesive manufacturer
• Allow the primer to dry in accordance with manufacturer instructions
• If necessary, apply dam foam to the inside edge of the pinch weld
• Refit clips to the aperture. Clips damaged during removal should be replaced

NOTES

1. These methods should be applied when the aperture is undamaged and the previously installed adhesive is fully cured. Otherwise the bead should be removed from the entire perimeter of the aperture and the pinch weld repainted, prior to installation of the glass

2. Unless the adhesive manufacturer states, do not prime the old adhesive bead as this could affect the bond between the old and new direct glazing adhesive

3. In the case of repainted aperture (e.g. rust repair or panel work), ensure the paint has had sufficient time to dry (24 hours minimum)

4. Take care not to drop primer onto the dash, paint work or trim. Use extra covers to prevent the possibility of damage

Preparing the glass

• If the removed glass is to be refitted, remove old adhesive from the glass
• Use an appropriate glass cleaner to clean the inner surface of the glass and allow to dry thoroughly
• Use lint-free glass wipers to clean the bonding surface and edge of the glass using the glass cleaner/activator or wash primer in accordance with the manufacturer's instructions 
• Ensure the glass primer is ready for application as recommended by the manufacturer. Some products can be used without a glass primer if the windscreen has a ceramic frit
• Ensure the glass primer has not exceeded its shelf life
• Using a suitable applicator apply an even coat of glass primer to the glass bonding surface in a single direction. Painting the primer back and forth can affect the bond
• Allow the glass to dry thoroughly in accordance with the manufacturer's instructions

Applying the adhesive bead

• Ensure the direct glazing adhesive has not exceeded its shelf life
• Using an extrusion gun, apply a continuous bead of direct glazing adhesive to the pinch weld or glass so the new bead is approximately 5mm to 6mm greater in height than the dam

Installing the glass

• Install within the time specified by the direct glazing adhesive manufacturer
• Position the glass centrally in the aperture, insert the spacer blocks (if applicable) and bed the glass into place 
• Properly refit all components removed earlier 
• It may be necessary to tape down moulds while the direct glazing adhesive is curing. Use tape that will not affect the vehicle's paint work. Inform the customer of safe removal time for any adhesive tape used

Cleaning-up 

• Use a cleaner or solvent specified by the adhesive manufacturer to remove excess adhesive from the glass, moulds, trim and paint work
• Clean the glass with glass cleaner
• Remove the protective covers and carry out the final inspection
• Complete invoice and warranty Information

Drive-away time

Inform the customer about curing time requirements. Take due regard to ambient weather conditions and installation methods and materials. Adhesive cures progressively due to reaction within the moisture in the air and the adhesive manufacturer's recommendations should be explained to the customer to ensure the correct cure level and strength is achieved before the vehicle is driven.

Remember - windscreens fitted to vehicles with passenger side airbags will require a longer drive-away time. This is due to the passenger's airbag relying on the windscreen to control how it inflates.

Where direct-glazed rearlights are replaced, an extended drive-away time should be used. If such time is not adhered to and the side window is wound down while the vehicle is in motion the force of the wind could dislodge the rearlight.

 
Direct Glazing Adhesives

Adhesives must meet all relevant Australian Standards. All components of the direct glazing adhesive system must be within their ‘used by’ or ‘best before’ dates at the time of use.

There are three main adhesion methods:

1. Direct glazed adhesive bonded windows

• Direct glazing adhesive is used to bond the window to the flange to achieve a 100% seal
• Significantly improves torsional stiffness
• Prevents leakage
• Improved aerodynamics and design
• Allows fast windscreen removal with cutting wire or integrated copper wire
• Good thermal insulation
• Drawbacks: several steps are needed and some direct glazing adhesive systems require additional primer and activator application

NB: always follow the direct glazing manufacturer’s instructions and use all the components from the same manufacturer to ensure compatibility

2. Butyl taped

• A sticky butyl ribbon is used for attaching the window to the body flange
• Better sealing performance than a rubber gasket
• Fast and clean installation
• Improved aerodynamics and design
• Allows fast windscreen removal with cutting wire or integrated copper wire
• Good thermal insulation
• Drawbacks: airbag cannot be fitted properly (poor safety) and contributes less to overall torsional stiffness of car bodies than directly glazed adhesive bonded windows 

3. Rubber mounted

• Window is mounted and sealed to the vehicle body with a moulded rubber gasket, e.g. some trucks, buses, excavators, cars, etc.
• This method is fast and easy, clean removal and installation
• Drawbacks: airbag cannot be fitted properly (poor safety), old rubber mouldings mean higher risk of leakages, need for maintaining a large inventory, cannot achieve lower aerodynamic drag, is a sealing function only and will not improve body rigidity

Disclaimer:  
The above information provides AGA members with an overview of fitting procedures. Members are reminded that compliance with Australian Standards is a requisite of membership. The AGA accepts no responsibility or liability for the incorrect interpretation or fulfilment of these or any other regulations pertaining to the automotive glass industry. This information is meant to serve as a guideline only, and all Australian businesses involved in windscreen repair and replacement are strongly advised to purchase and refer to a copy of the actual Australian Standards documents, and to be familiar with the requirements specified by their relevant State Motoring Authority.