The first thing people think of when talking about urethane in a windshield application is drive away time. All urethane manufacturers have safe drive away times, which depend on many factors including humidity, temperature, and size of the urethane bead. While safe drive away time is absolutely a very important factor when deciding what type of urethane to use, it should not be the ONLY factor that is used.
The two very important factors that are often overlooked and misunderstood about urethane is non-conductive and high modulus. With the technological advances that have been made specifically to automotive glass, there is now a requirement from vehicle manufactures to be sure to include these properties in their adhesives. You may be asking yourself, “why should I care about these?” or “what do these have to do with my vehicle?” Read on to find out why you need to know about these, and how using the incorrect urethane can affect your windshield installation.
Many new windshields are manufactured with electrical components running directly through them. This includes heads up displays, electrochromic mirrors, light sensors, rain sensors, and antennas. Non conductive adhesives create an electrical barrier between the glass and the body of the vehicle which significantly reduce electrical currents. If this proper urethane is not used on vehicles with these options in the windshield, you may run into problems with them not working properly.
High modulus urethanes are measured by how stiff it is at a “full cure”. What this does is meets the manufacturer’s requirements for joint movement when a given amount of force is applied to the bonded joint. Vehicles are structurally designed based on many variable factors, one of them being a high modulus urethane. If your windshield is ever replaced with an aftermarket urethane that is not high modulus, you are greatly depreciating the overall structure of your vehicle in the event of a collision or rollover.
In conclusion, no matter which automotive repair facility you have your windshield replaced at, ALWAYS be sure that the urethane they are using incorporates all the key elements of a proper urethane: safe drive away time, non-conductive, and high modulus.