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Hollow Window Seals
Hollow bulb seals feature a bulb-shaped sealing element with an internal cavity that compresses as the window closes. The hollow design allows the profile to deform more easily than many solid compression seals, helping create sealing contact while reducing the force required to operate the window.
Quanex offers hollow bulb weatherseals in a range of profile dimensions to accommodate different mounting requirements, opening sizes, and window designs. For engineers evaluating weatherseal options, hollow profiles can provide an effective balance between sealing performance and operating force, particularly in applications where ease of operation is an important design consideration.
Why Engineers Choose Hollow Window Seals
The internal cavity of a hollow weatherseal gives the bulb space to compress and change shape when it contacts the opposing surface. This allows the seal to establish contact without requiring the same level of material deformation as a solid profile.
For many window systems, that difference can help reduce operating force while still maintaining the sealing interface required by the design. Because compression force is influenced by profile geometry, material construction, opening size, and system design, engineers should evaluate the complete sealing arrangement rather than relying on a single dimension or specification.
When selecting a hollow bulb weatherseal, key considerations include the available opening, required reach, bulb diameter, mounting dimensions, and expected compression range. Reviewing these factors together helps identify profiles that fit the mounting interface, provide appropriate contact, and support the performance objectives of the finished window system.
- Need to reduce operating force? The hollow cavity allows the bulb to compress more easily than many solid compression profiles, helping reduce the force required to open and close windows. Selecting a bulb with slip coat on the bulb also greatly reduces the friction and operating forces.
- Looking for a balance between sealing performance and usability? Hollow bulb designs can help establish sealing contact while avoiding some of the resistance associated with more rigid compression profiles.
- Working with frequently operated windows? Operating force becomes increasingly important in applications where windows are opened and closed regularly. Engineers often evaluate hollow bulb designs when ease of operation is an important performance objective.
- Need flexibility in profile selection? Hollow bulb weatherseals are available in multiple dimensions and configurations, allowing engineers to balance reach, opening size, and compression requirements.
- A weatherseal that seals well but is difficult to operate can create its own problems. Increasing sealing force is not always the best solution. Hollow bulb weatherseals are often selected when engineers need sealing contact without unnecessarily increasing operating force.
- Not every gap requires a solid compression profile. In some applications, a solid profile may require more force to achieve the same sealing objective. Hollow bulb designs provide an alternative approach by allowing the sealing element to deform into the internal cavity during compression.
- Compression range matters as much as profile size. A profile that is under-compressed may not establish consistent sealing contact, while excessive compression can increase operating force and impact long-term performance. Engineers should evaluate the expected compression range as part of the overall system design.
- The best weatherseal is part of a complete system. Operating force, hardware design, available opening, profile geometry, and sealing objectives all influence performance. Weatherseal selection should support the goals of the complete window system rather than optimize a single dimension.
Weatherseals
Hollow Window Seal Comparison
Find the right hollow seal for your window design
Every window design has unique dimensional and performance requirements. Quanex can help you evaluate hollow weatherseal profiles based on your mounting geometry, available opening, and application needs.
Contact our team to discuss your design requirements and explore the right weathersealing solution.
This page was last updated on November 13, 2026. Downloaded document versions may differ. Please check the individual documents for most current version.