Standard & Custom Extruded Bulb Seals Specifications

Meltpoint Plastics International manufactures high-quality extruded bulb seals designed to provide reliable compression, flexibility, and long-term sealing performance. Available in standard and custom profiles, our bulb seals are engineered for window and door systems, architectural applications, and industrial sealing solutions.

We offer extruded bulb seals in TPV, silicone, and EPDM, as well as coextruded TPV/PVC profiles that combine a flexible sealing bulb with a more rigid base for secure installation.

Material Options & Compression Guidelines

TPV (Thermoplastic Vulcanizate) Bulb Seals

TPV bulb seals offer excellent flexibility, weather resistance, and compression recovery. Commonly used in window and door applications, TPV provides an effective balance of durability and sealing performance.

  • Suggested operating compression: 25%–40% of free bulb height
  • Typical hardness range: 45–75 Shore A, formulation dependent
  • Material properties: UV resistance, ozone resistance, weatherability, and flexibility
  • Applications: Window systems, door seals, glazing assemblies, and weatherstripping

Silicone Bulb Seals

Silicone bulb seals provide excellent flexibility across a broad temperature range, making them suitable for applications requiring consistent sealing performance under demanding environmental conditions.

  • Suggested operating compression: 20%–35% of free bulb height
  • Typical hardness range: 30–70 Shore A, formulation dependent
  • Material properties: Excellent temperature resistance, UV stability, ozone resistance, and flexibility
  • Applications: Specialty windows, doors, enclosures, and temperature-sensitive sealing systems

EPDM (Ethylene Propylene Diene Monomer) Bulb Seals

EPDM bulb seals are designed for long-term outdoor exposure, providing excellent resistance to weathering, ozone, and moisture. EPDM is widely used in architectural sealing applications.

  • Suggested operating compression: 25%–40% of free bulb height
  • Typical hardness range: 40–80 Shore A, formulation dependent
  • Material properties: Excellent weather resistance, ozone resistance, moisture resistance, and elastic recovery
  • Applications: Windows, doors, architectural glazing, and exterior sealing systems

Coextruded TPV/PVC Bulb Seals

Our coextruded bulb seals combine a flexible TPV sealing section with a rigid or semi-rigid PVC attachment base. This dual-material construction allows for reliable sealing performance and secure installation in compatible channels or framing systems.

  • Suggested operating bulb compression: 25%–40% of free bulb height
  • Flexible bulb material: TPV
  • Base material: Rigid or semi-rigid PVC
  • Material properties: Flexible sealing surface, structural attachment support, weather resistance, and dimensional stability
  • Applications: Window frames, door systems, glazing assemblies, and custom architectural profiles

Custom Bulb Profiles

Our custom extrusion capabilities allow us to develop bulb profiles tailored to specific installation and performance requirements, including:

  • Custom bulb heights, widths, and wall thicknesses
  • Application-specific compression targets
  • Hollow and solid bulb configurations
  • Custom attachment bases and retention features
  • Dual-material TPV/PVC coextrusions
  • Material and hardness selections based on application requirements

Compression Performance

Bulb seal compression is expressed as a percentage of the bulb’s original, uncompressed height.

Compression (%) = [(Original Bulb Height − Installed Bulb Height) ÷ Original Bulb Height] × 100

For example, a bulb with an original height of 0.500 inches compressed to 0.350 inches achieves 30% compression.

Proper compression is important for maintaining an effective seal while minimizing excessive installation force and premature material deformation.

Technical Note: Recommended compression varies depending on bulb geometry, wall thickness, material hardness, operating temperature, and installation conditions. Compression percentages represent preliminary design guidance and should be validated through application-specific testing.

Custom Extrusion Solutions

At Meltpoint Plastics International, we work with customers to develop extruded bulb seals that meet specific dimensional, material, and performance requirements. From standard profiles to specialized coextruded designs, our manufacturing capabilities support dependable sealing solutions for a wide range of industries.

Contact our team to discuss your standard or custom bulb seal requirements.