Auto Glass Adhesives and Urethanes

Your car or light truck’s windshield, as well as its back glass, or rear window, and many of the vent windows are attached to the vehicle using an adhesive system.  This adhesive system is a glue-like product that will hold the Seattle auto glass in place, and meet all Federal requirements for preserving the safety of your vehicle’s crash safety system.

The system utilized to adhere the glass to the vehicle’s frame is critically important in preserving your vehicle’s safety and integrity. Improper application of the adhesive products or improper mixing of adhesive systems could cause the bonding to fail - resulting in death or injury to you or your vehicle’s passengers if the bonding system fails.

Glass Doctor® of Seattle uses only AGRSS® approved urethane based adhesive products from Sika and Dow Automotive in your vehicle. 

Seattle Auto Glass - Types of Bonding Systems

In the 1950’s, when chemical adhesive systems began to replace mechanical systems (like rubber gaskets and clips) in the installation of windshields, the most common bonding system was butyl tape. This is a soft and sticky material that came in rolls. It was essentially a ribbon of low strength rubber used between the Seattle auto glass and the pinch weld of the vehicle to hold the Seattle auto glass in place. It no longer meets Federal motor vehicle safety standards for modern cars.

After butyl came polysulfide based adhesives. This adhesive system was much stronger than butyl, but took significant amount of time to cure and become strong enough to safely operate the vehicle. This is OK if the vehicle is at the manufacturer and it will be several days or weeks before it is sold, but this application doesn’t work well for you, the consumer, who would like to ensure a faster safe drive away time.

1973 saw the first use of urethane based adhesive systems in cars - starting with the 1973 Oldsmobile Cutlass.  This super-strong adhesive quickly replaced butyl and polysulfide as the system of choice due to its quick cure time, strength and reliability.  In fact, Glass Doctor of Seattle only uses urethane adhesive systems in replacements where a chemical bonding system was originally used - even if the original adhesive system was butyl or polysulfide.

Urethane comes out of the tube with a paste like consistency, and must be allowed to harden, or cure. Under most circumstances, the urethane systems used by Glass Doctor of Seattle will cure in one hour. Temperature and humidity will sometimes impact the cure time for the urethane, and cause the safe drive away time to be longer in some applications. Your certified technician will advise you of the safe drive away time when your installation is complete. 

Seattle Auto Glass - Why Does Glass Doctor of Seattle Use Urethane?

Urethane has many advantages over older bonding systems:

  • Urethane is 3 to 50 times stronger than older adhesives
  • Urethane is flexible, allowing it to flex with the vehicle body over bumps
  • Urethane bonds well with smooth surfaces like glass and rougher surfaces like automotive metals and paints
  • Urethane is UV, chemical and water resistant
  • Urethane has a tensile strength in automotive applications of at least 500 PSI
  • Urethane has a lap shear strength in automotive applications of at least 500 PSI
  • Urethane is non-conductive – reducing electrical interference

Urethane is easy to apply with proper training and tools.  Glass Doctor of Seattle uses “one-part” urethane, which provides for a consistent quality product. We also utilize “foil packs” or “sausages” for our installations. This packaging minimizes the waste that traditional aluminum and cardboard tubes generate, reducing our garbage and helping reduce our impact on the environment.

Some applications, especially high performance vehicles like BMW, Audi and Mercedes-Benz, require the use of a high modulus urethane. This type of urethane provides extra strength to better resist torsional stresses and enables the windshield itself to help strengthen the car’s chassis and improve handling. Glass Doctor of Seattle follows manufacturer requirements, and will make sure to use high modulus urethane when specified by your vehicle manufacturer.

Seattle Auto Glass - Adhesive Systems

Urethane is only part of a comprehensive adhesive system utilized by Glass Doctor of Seattle.  The systems used by Glass Doctor are comprised of four parts:

  • Glass Doctor Glass Cleaner
  • Primer
  • Urethane
  • Metal primer

These systems, designed by Sika and Dow Automotive, work together chemically to ensure the safest possible Seattle auto glass installation.  Our technicians are certified by Sika and Dow Automotive, and are required to pass certification tests in order to properly use and apply the proper adhesive system to your vehicle. 

Your certified Glass Doctor technician will assess the Seattle auto glass installation and ensure that the adhesive system is not only the proper one for the application, but also that the following safety factors are reviewed and managed as part of the process:

  • Presence of foreign materials in the adhesive bonding area, such as:
    • Solvents, lubricants, cleaners
    • Dust and dirt
    • Greases and oils
    • Rust or deformity
    • Condition of the paint
    • Ensuring the adhesives have not passed shelf life or expiration

The technician will also record the adhesive system information and lot numbers on his inspection sheet to maintain a record of the installation process and the adhesive used in accordance with AGRSS standards.

Throughout our website, we will try and provide you with the information and background necessary to make an informed decision on your Seattle auto glass replacement needs.  The decision should not only be about price, and the more you know as a consumer, the more confident you will be making the right decision for your Seattle auto glass repair or replacement needs. From Ballard to Bellevue, Puyallup to Kirkland and Redmond to Renton -  throughout King and Pierce Counties, Glass Doctor of Seattle brings a commitment to safety and best practices to every install we do.