When our customers are in the midst of a restoration project, they often inquire about the use of butyl tape. Whether it was their initial choice or a recommendation for a glass installation, the fact that we, the weatherstripping experts, don’t offer butyl tape may come as a surprise. However, there’s a specific reason behind this decision, and in this post, we’ll delve into why we opt for alternatives and what we suggest instead.
Originally, auto manufacturers used rubber gaskets to install windshield and rear window glass, a process that was time-consuming on the assembly line. However, in the mid-60’s, General Motors revolutionized the industry by switching to butyl tape, a faster and more efficient method that soon became the norm among other car manufacturers.
As cars transitioned from the traditional body-over-frame to unibody construction in the mid-60’s, the importance of windshield and rear window strength became paramount. With the body now serving as the vehicle’s frame, these windows needed to provide structural support. While butyl tape was effective for sealing, it became clear that it lacked the strength required for modern vehicles.
During this era, advancements in adhesive technology led to the rise of urethane adhesive as the superior choice. Its exceptional sealing properties, strength, and flexibility make it an ideal solution. According to the 3M website, urethane structural adhesives react upon mixing, eliminating the need for moisture to cure. They offer a level of flexibility after curing, resulting in outstanding impact and vibration resistance, making them the perfect fit for this specific application.
By the mid-70s, the gradual transition to using urethane adhesive for bonded windshields and rear windows began, eventually becoming the standard practice by the 1980s.
While butyl tape still remains available on the market for various applications, we highly recommend using urethane adhesive for windshield and rear window installations. This adhesive boasts fast curing times, creates a durable and strong bond, and is readily accessible, including the trusted 3M Brand. Available in a convenient caulk-style tube for easy application, it typically cures within 24 hours, ensuring a secure and long-lasting hold.
How to Use it
To set your windshield or rear window with it, simply run a bead on the edge the glass sits on, push the glass down on it and leave it to cure. You’ll also want to use spacers to get the glass lined up just right and hold it in place until the adhesive cures.
Urethane adhesive can also be used to attach universal beltline or beltline weatherstrip without tabs. Simply run a bead on the gluing surface, push the beltline on and use some wooden clothespins or wood clamps to hold it in place. Remove the clamps after 24 hours and you’ll be ready to go!
We also have an instructional video demonstrating how to attach beltline weatherstripping with urethane adhesive. You can watch that here.
At Steele, we’re more than just high-quality products, we’re your trusted resource for completing your weatherstripping projects with confidence.
Whether you’re working on a classic car or truck, street rod, RV, or boat, our expert team is here to help. If you have questions about weatherstripping or need product guidance, we’re just a call or click away.
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