Laminated glass has a rich history dating back to 1903 when French chemist Édouard Bénédictus discovered a plastic interlayer that bonded two pieces of glass. This groundbreaking invention kept the glass intact even when broken, paving the way for various applications of safety glass. Despite its commercialisation not occurring until the 1930s, this pivotal discovery has led to significant advancements in safety glass technology.
Early developments in safety glazing
Before 1998, polyvinyl butyral (PVB) was the primary material used for laminated glass interlayers. Developed in the early 1930s through a collaborative R&D program involving DuPont, Libbey-Owens-Ford Glass Co., Monsanto, Pittsburgh Plate Glass (PPG), and Carbide and Carbon Chemicals Corp. (Union Carbide), PVB provided a flexible and durable solution for automotive windshields. Laminated glass fabricators used PVB to bond two plies of glass, creating a unit that retained broken glass particles after breakage.
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In 1966, the ANSI Z97.1 standard for glass in buildings was introduced, followed by the Consumer Product Safety Commission (CPSC) regulation 16CFR 1201 in 1977. These standards focused on reducing cutting and piercing injuries from glass in doors and adjacent areas, incorporating tempered or laminated glass to enhance safety.
The Introduction of the SentryGlas interlayer
While existing safety glazing standards protected people, there were no regulations for property protection against extreme weather until Hurricane Andrew struck South Florida in 1992. The hurricane's devastation highlighted the need for more resilient glazing solutions. Although laminated glass initially helped retain broken glass, the flexibility of PVB hindered its performance in large missile impact tests.
DuPont scientist Anthony Smith recognised the need for a stiffer interlayer, leading to the development of the SentryGlas ionoplast interlayer. Originally known as SentryGlas Plus (SGP), this interlayer offered superior performance over PVB composites. Now known as SentryGlas, this interlayer has been revolutionising safety in impact systems for 25 years.
Certifying hurricane-proof systems
South Florida's stringent testing requirements for glass and glazing products led to mandatory certification from the outset. Successful testing resulted in a Notice of Acceptance (NOA), ensuring product quality and giving property owners confidence in their hurricane resilience. The ionoplast interlayer was extensively tested and proven in various residential and commercial systems, demonstrating excellent performance and quality.
Ray Crawford, President of Crawford-Tracy Glass Corporation, a leading glazing contractor, stated, "In the early days, we spent considerable time testing systems to meet Dade County's impact and cycling requirements. The SentryGlas interlayer emerged as the best solution to pass the large missile test followed by cycling. We have not seen any delamination from SentryGlas laminates since we began installing the product."
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Today, thousands of projects in Florida utilise impact systems for hurricane protection, including schools, hotels, hospitals, and government buildings. Notable projects include the Porsche Design Tower and the Judicial Center and Courthouse in West Palm Beach, both featuring SentryGlas laminated glass.
Looking ahead
The 25-year history of SentryGlas has profoundly impacted the laminated glass industry, particularly in hurricane-prone regions. Its stiffness and strength have enabled the development of windows, doors, storefronts, and curtain wall systems that provide continuous protection against extreme weather events. These innovations have resulted in safer living and working environments, eliminating the need for boarding up or deploying shutters during weather alerts. Building interiors remain protected against water and wind infiltration, maintaining an unobstructed view of the exterior.
