FAQ > Urethane Adhesives Knoxville's Finest Auto Glass Installation Center • I have a Volkswagen Beetle.  When I called Phoenix Glass for a price  on a new windshield, the customer service representative told me my  VW called for the application of a different type of adhesive called High  Modulus Urethane.  I understand it's a form of Urethane but how does  it differ from the type normally used? The short answer is that your VW, along with many other German automobile  manufacturers, have mandated a rigidity requirement on the vehicles that they  produce.  In order to meet that engineering requirement and retain the structural  integrity of the vehicle it is necessary to use a different type of urethane.  High Modulus  urethane adhesives provide the extra strength to help the vehicle resist torsional twisting  as well as help quiet and stabilize the vehicles ride.  Another added plus that is built into High Modulus Urethane is that it  preserves radio, cell phone, and global positioning system reception in OEM antenna encapsulated windshields and backlites.  The long answer is now that you have learned how important it is and how it all works together we're  going to recap a bit as we get into why it's so important to not only make sure your new windshield is  installed with a High Modulus adhesive but with the "right OEM type" of High Modulus Urethane.  If you  read multiple adhesive manufacturers literature to determine whether their urethane is high modulus,  you will find different definitions of the term. Some manufacturers define their adhesives as "modulus  enough" or "high on the OE specification for high modulus classification," but does that really mean that  they can be classified as high modulus adhesives?  To answer that question, first we must define what  high modulus means.  High modulus is a rigidity requirement of cured adhesive.  It measures the ability  of the adhesive to withstand a variety of stresses and still return to its original form.  It must be able to  withstand tension, compression, shear and torsion without adhesive or cohesive failure.  High  performance and luxury vehicle manufacturers specify and use adhesives like BETASEAL ONE because they can use it as a  structural element to stabilize the vehicle which improves the ride and reduces rattles, vibrations and other vehicle noises. High  modulus adhesives have a much higher resistance to stress.  This characteristic enables high modulus adhesives to stiffen the  vehicle body, improving handling and overall stability in vehicles designed to use this advanced technology.  Vehicle designers  place greater demands on high modulus adhesives.  The adhesive bears much more of the pushes, pulls and twists associated  with everyday driving.  High modulus adhesives must have a higher elastic resistance than normal so they will not deform or  rupture under the increased stress.  So how do adhesive manufacturers know which property and specification should be met in  order to be high modulus? To clarify, it must be understood that an adhesive is either high modulus or it is not.  There is no in  between modulus that is good enough for all vehicles.  According to Mercedes specifications, in order for an adhesive to be considered high modulus, it must meet 2.5 MPa.  Dow Automotive's Betaseal One Urethane Adhesive passes the defining test to be called high modulus with a shear strength of  2.7 MPa at full cure.  The Bottom Line A urethane manufacturer cannot claim to be "on the high end of the specification" and therefore be considered "modulus  enough" for all vehicles.  Any urethane manufacturer claiming to be high modulus should be able to provide supporting data, to  include laboratory testing as well as technical data.