Sealant Compatibilities for Vanceva Laminated
Architects, engineers and glaziers are faced with a complex decision when selecting sealants to best satisfy building project requirements. There are a number of generic type sealants, each with its own base material. Within a generic type, individual sealant formulations will have varying quantities of plasticizers, solvents, curing agents and/or fillers. Each product is specifically formulated to provide properties making is suitable for some applications, but not for others. Understanding these products and their inherent properties is a critical requirement in making the proper overall sealant choice.
When installing laminated glass, Solutia recommends resilient non-hardening sealant compounds, tapes or elastomeric gaskets (wet or dry glazing). Generic wet glazing compounds include butyl or polybutyl tapes, acrylics, polyurethanes, polysulfides and silicones. The most generally used products are essentially 100% solid. The glazing techniques typically followed are set forth in the Glass Association of North America’s Glazing Manual. These guidelines state that laminated glass should not be exposed to direct contact with organic solvents, and weep systems should be incorporated to prevent exposure to water for prolonged periods. Either exposure can lead to delamination or haziness along the laminated edge. Laminators recommend that sealant compatibility be checked for the same reasons.
Gaskets and tapes are by definition normally non-flowing in form. Therefore, contact between the polyvinyl butyral interlayer and gaskets or tapes are rare. If contact does occur, it is usually due to specific design that intentionally places the material on direct contact with the laminated glass edges. Setting blocks will come in contact with the laminated glass edge and the compatibility of such elements should be considered. Setting block compatibility is outside the scope of this study. Past glazing practices and applications have indicated that Non-staining EPDM rubber or Santoprene material have been successfully used as a setting block material in conjunction with laminating glass made with Solutia branded interlayers.
When selecting a sealant for a glazing system, the specifier must consider a number of influences including-
- Resistance to water penetration into the structure under all weathering conditions.
- Sealant weatherability. Does it deteriorate or change physically over time?
- Initial and life cycle economics. (Sealants should be evaluated using the same life cycle criteria as glazing).
- Mechanical properties, such as the ability to accommodate thermal movement, adhesion, etc.
- Compatibility with the other elements in the glazing system, including the laminated glass where the sealant or sealant by-products are likely to contact on another.
Sealant Types
In most installations where the sealant is used as a weather seal, the sealant material rarely comes into contact with the glass edge. However, in butt joint glazing (structural glazing), in installations where a heel or toe bead is applied and in organically sealed insulating glass units, the sealant will come into contact with the edge of the glass and possible with the interlayer in laminated glass. It is in this area that questions about compatibility arise.
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