{"id":213219,"date":"2025-12-01T11:21:14","date_gmt":"2025-12-01T16:21:14","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=213219"},"modified":"2025-12-12T12:22:05","modified_gmt":"2025-12-12T17:22:05","slug":"40-year-study-of-silicone-sealants-silicone-versus-alternative-chemistries","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/40-year-study-of-silicone-sealants-silicone-versus-alternative-chemistries\/","title":{"rendered":"40-year study of silicone sealants: Silicone versus alternative chemistries"},"content":{"rendered":"
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Photo \u00a9 Shutterstock\/courtesy Momentive Performance Materials Inc.<\/em><\/figcaption><\/figure>\n

As structural glazing systems become more ambitious and complex, and demands for durability and sustainability continue to rise, the longevity of building materials has never been more critical.<\/p>\n

Sealants play a crucial role in the long-term performance and weatherproofing of curtain walls and glazing systems. Choosing the right sealant can mean the difference between decades of low-maintenance performance and costly repairs and system failures.<\/p>\n

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Figure 1: An excerpt from the 1966 issue of Time Saver Standards. Tables courtesy Momentive Performance Materials Inc.<\/em><\/figcaption><\/figure>\n

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In fact, it is long been known \u201cthe sealing material is typically the most critical element of the joint assembly affecting durability,\u201d as this excerpt from the 1966 edition of Time Saver Standards states (Figure 1).2<\/sup><\/p>\n

But which chemistry stands the test of time?<\/p>\n

This article presents the results of one of the longest-running glazing sealant studies\u2014a 40-year outdoor weathering assessment comparing silicone, polyurethane, and acrylic-based sealants. Conducted at the Atlas Weathering Test Site in Florida, this real-world study provides compelling insights for architects, specifiers, building envelope engineers, and contractors seeking to make informed material selections that impact every aspect of the building envelope.<\/p>\n

The feature highlights the performance of silicone chemistries, especially acetoxy and alkoxy types, by comparing key properties such as adhesive strength, cohesive strength, flexibility, toughness, resilience, hardness, surface appearance, and long-term durability under extreme heat, UV, and humidity conditions. It also provides comparative data to inform specification decisions.<\/p>\n

Table 1<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
ID #<\/strong><\/td>\nPolymer type, descriptors<\/strong><\/td>\nManuf<\/strong><\/td>\nFiller type<\/strong><\/td>\nColor<\/strong><\/td>\n<\/tr>\n
1<\/td>\nSilicone, 1PT, +\/-25%, Ac<\/td>\nA<\/td>\n100% Fumed Silica<\/td>\nWhite<\/td>\n<\/tr>\n
2<\/td>\nSilicone, 1PT, +\/-50%, Al<\/td>\nA<\/td>\nCalcium Carbonate \/ Fumed Silica<\/td>\nGray<\/td>\n<\/tr>\n
3<\/td>\nSilicone, 1PT, +\/-50%, Al<\/td>\nA<\/td>\nFumed Silica<\/td>\nTrans\/Clear<\/td>\n<\/tr>\n
4<\/td>\nSilicone, 1PT, +\/-50%, Al<\/td>\nA<\/td>\nCalcium Carbonate \/ Fumed Silica<\/td>\nGray<\/td>\n<\/tr>\n
5<\/td>\nSilicone, 1PT, +\/-50%, Al<\/td>\nB<\/td>\nCalcium Carbonate \/ Fumed Silica<\/td>\nGray<\/td>\n<\/tr>\n
6<\/td>\nSilicone, 1PT, +100\/-50%, Am<\/td>\nB<\/td>\nCalcium Carbonate \/ Fumed Silica<\/td>\nLimestone<\/td>\n<\/tr>\n
7<\/td>\nSilicone, 1PT, +\/-25%, Ac<\/td>\nB<\/td>\n100% Fumed Silica<\/td>\nBlack<\/td>\n<\/tr>\n
8<\/td>\nSilicone, 1PT, +\/-25%, Ac<\/td>\nC<\/td>\n100% Fumed Silica<\/td>\nBlack<\/td>\n<\/tr>\n
9<\/td>\nSilicone, 1PT, +\/-25%, Ac<\/td>\nD<\/td>\n100% Fumed Silica<\/td>\nBlack<\/td>\n<\/tr>\n
10<\/td>\nPolyurethane, 2PT, +\/-50%<\/td>\nD<\/td>\nFumed Silica<\/td>\nBlack<\/td>\n<\/tr>\n
11<\/td>\nAcrylic Terpolymer, 1PT, XX<\/td>\nD<\/td>\nCalcium Carbonate<\/td>\nBlack<\/td>\n<\/tr>\n
12<\/td>\nPolyurethane, 1PT, +\/-25%<\/td>\nE<\/td>\nCalcium Carbonate \/ Fumed Silica<\/td>\nLimestone<\/td>\n<\/tr>\n
13<\/td>\nPolyurethane, 1PT, +\/-25%<\/td>\nF<\/td>\nCalcium Carbonate<\/td>\nGray<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Description of sealant products.<\/p>\n

The need for long-term data<\/h2>\n

Modern buildings are expected to last many decades, some for centuries. That is why it is important for modern materials to have long-term performance data under real-world conditions. While accelerated aging tests provide useful insight, nothing replaces real-world testing of the effects of outdoor exposure over extended periods.<\/p>\n

That is why GE Silicones (now Momentive Performance Materials) launched one of the world\u2019s most ambitious sealant weathering studies in 1983, applying a variety of sealant chemistries to test panels and leaving them exposed to Florida\u2019s tropical climate.<\/p>\n

The 9-ha (22-acre) Atlas Weathering Test Site (the first approved testing facility for the Cool Roof Rating Council) offered an ideal environment for the study. With high humidity, intense UV radiation, and regular tropical storms, the Florida climate is one of the most challenging natural environments for testing the durability of glazing sealants.<\/p>\n

Key findings: A summary<\/h2>\n

After 40 years of outdoor exposure, the results are unanimous: silicone sealants consistently outperformed polyurethane and acrylic in durability, elastic recovery, and surface integrity, demonstrating long-term performance. Although the test focused on sealants, these same chemistries are used across curtain wall and glazing applications.<\/p>\n

Study parameters<\/h3>\n

The panels used in the study featured square pieces of glass and painted aluminum substrates, mounted on outdoor racks facing south at a 45-degree angle. Thirteen sealants from six different manufacturers were applied and were evaluated at 22-, 30-, and 41-year intervals for:<\/p>\n