Silicone Products Silicone Sponge Rectangles

What Are Silicone Sponge Rectangles?

Silicone sponge rectangles are closed-cell silicone extrusion profiles manufactured in flat rectangular or strip configurations for sealing, gasketing, cushioning, insulation, and gap filling. Their closed cell construction provides greater compressibility than solid silicone while maintaining temperature stability and environmental resistance.

Bellofram Elastomers manufactures custom extruded silicone sponge rectangles in continuous roll form with virtually any combination of thickness and width up to a 12” usable width. From narrow sealing strips to wider profiles for large assemblies, dimensions, density, color, and formulation can be tailored to meet specific application requirements.

Key Takeaways

• Silicone sponge rectangles are closed-cell extruded profiles used for sealing, gasketing, cushioning, and insulation.
• Available in custom combinations of thickness and width up to a 12” usable width.
• Supplied as continuous roll material for flexible cutting and installation.
• Available in density grades ranging from soft to firm.
• Designed for continuous operating temperatures from -85°F to +400°F.
• Closed-cell construction provides compressibility and low water absorption.
• Flame-retardant versions are available to meet UL 94 V-0 and UL HB requirements.
• FDA-grade and NSF 51 certified material options are available.
• Custom colors and formulations can be developed for application-specific requirements.
• Ideal for HVAC, electrical enclosures, transportation, aerospace, industrial equipment, and other demanding sealing applications.

Why Choose Silicone Sponge Rectangles?

Silicone sponge rectangles provide a simple, versatile seal combined with the compressibility of closed-cell silicone sponge.

Unlike a complex custom profile, rectangular sponge extrusions provide a flat sealing surface that can be manufactured in different widths and thicknesses to fit channels, equipment panels, enclosure doors, mating surfaces, and other straightforward sealing configurations.

Benefits of Silicone Sponge Rectangles

BENEFIT	WHY IT MATTERS
Custom Width and Thickness	Allows rectangular extrusion dimensions to be tailored to specific gaps, channels, sealing surfaces, and assembly requirements.
Closed-Cell Construction	Provides compressibility while helping minimize water absorption in environmental sealing applications.
Low Closure Force	Sponge construction compresses more easily than solid silicone, helping create a seal without excessive clamping force.
Continuous Roll Material	Provides flexible installation and allows material to be cut to the required length for different applications.
Wide Temperature Range	Maintains physical integrity across continuous operating temperatures from -85°F to +400°F.
Multiple Density Options	Soft through firm constructions allow compression resistance and cushioning to be matched to the application.
Specialty Formulations	Flame-retardant, FDA-grade, NSF 51 certified, custom-color, and other application-specific formulations are available.

Silicone Sponge Rectangle Size and Material Options

Bellofram Elastomers manufactures silicone sponge rectangles as continuous extruded roll material in custom widths and thicknesses.

Silicone Sponge Rectangle Options

OPTION	AVAILABLE CAPABILITY
Profile	Flat rectangular closed-cell silicone sponge extrusion.
Width	Custom widths available up to a 12" usable width.
Thickness	Custom thicknesses can be paired with the required width to create application-specific rectangular profiles.
Format	Continuous extruded roll material.
Density	Available in density grades ranging from soft to firm.
Temperature Range	-85°F to +400°F.
Colors	Custom color options are available.
Custom Formulations	Materials can be tailored to functional, environmental, flammability, or regulatory requirements.

Standards and Specialty Silicone Sponge Rectangles

Bellofram Elastomers offers silicone sponge rectangle formulations for applications requiring enhanced flammability performance or materials suitable for regulated environments.

Silicone Sponge Rectangle Standards and Specialty Options

OPTIONS	TYPICAL APPLICATION
UL 94 V-0	Flame-sensitive applications requiring enhanced vertical-burn performance.
UL HB	Applications requiring horizontal-burn flammability performance.
NSF 51	Food and beverage equipment requiring appropriate certified and FDA compliant materials.
Custom Formulations	Application-specific silicone sponge compounds tailored to performance and environmental requirements.

Silicone Sponge Rectangles vs. Solid Silicone Rectangles

The primary difference between silicone sponge rectangles and solid silicone rectangles is material construction. Sponge rectangles contain a closed-cell structure that provides lower density and greater compressibility, while solid silicone rectangles are dense, non-cellular extrusions designed for firmer sealing and greater mechanical stability.

Silicone Sponge Rectangles vs. Solid Silicone Rectangles

FEATURE	SILICONE SPONGE RECTANGLES	SOLID SILICONE RECTANGLES
Construction	Closed-cell silicone sponge.	Dense, non-cellular silicone rubber.
Density	Lighter-weight profile construction.	Denser and heavier, solid elastomer construction.
Compression	Highly compressible and suited for lower closure-force sealing.	Firmer and less compressible, providing greater sealing force and mechanical stability.
Gap Filling	Well suited for uneven gaps and sealing surfaces requiring greater conformability.	Best suited where a firm, dimensionally stable rectangular seal is required.
Typical Priority	Compression sealing, cushioning, gap filling, insulation, and low closure force.	Mechanical durability, dense sealing, firmness, and dimensional stability.

For applications requiring a dense, rubber rectangular extrusion, explore our Silicone Rectangles.

Common Applications for Silicone Sponge Rectangles

Silicone sponge rectangles are used where a simple flat extrusion can provide reliable compression sealing, cushioning, insulation, or environmental protection.

Common Applications for Silicone Sponge Rectangles

APPLICATION	HOW SILICONE SPONGE RECTANGLES HELP
HVAC Equipment	Provides compressible gasketing around panels, doors, ducting, and air-handling equipment.
Electrical Enclosures	Helps seal equipment housings against moisture, dust, and changing environmental conditions.
Industrial Equipment	Provides cushioning, gasketing, insulation, and gap filling in machinery and fabricated assemblies.
Doors and Access Panels	Compresses between mating surfaces to create a flexible environmental seal.
Automotive and Transportation	Supports sealing and cushioning in applications exposed to vibration and temperature fluctuations.
Aerospace Components	Provides lightweight sealing, insulation, and cushioning in thermally demanding environments.
Food and Beverage Equipment	FDA-grade and NSF 51 certified options can support applicable regulated sealing applications.
Medical and Pharmaceutical Equipment	Specialty material options can support equipment requiring appropriate silicone formulations for sensitive environments.

Custom Silicone Sponge Strips and Rectangular Extrusions

One of the biggest advantages of extruded silicone sponge rectangles is dimensional flexibility.

Bellofram Elastomers can manufacture continuous rectangular profiles with custom combinations of width and thickness up to a 12” usable width. This allows engineers to specify the sealing strip around the actual assembly rather than relying on a limited catalog of standard dimensions.

Custom silicone sponge rectangles may be used as:

• Compression seals
• Gasketing strips
• Door and panel seals
• Cushioning strips
• Thermal insulation
• Gap-filling material
• Vibration-isolation strips
• Environmental seals
• Custom cut-to-length components

For applications requiring a more complex cross-sectional geometry, explore our Silicone Sponge Profiles.

For custom flat components cut directly from silicone sheet without hard tooling, explore our Flash Cut Silicone capabilities.

When Should You Choose a Silicone Sponge Rectangle?

A silicone sponge rectangle may be the right choice when your application requires a flat, compressible sealing strip without the complexity of a custom multi-feature profile.

Silicone sponge rectangles may be ideal when:

• A rectangular or flat strip geometry fits the application.
• A custom combination of width and thickness is required.
• Continuous roll material is preferred.
• Low closure force and compressibility are important.
• Gaps or uneven mating surfaces must be accommodated.
• Operating temperatures range from -85°F to +400°F.
• UL 94 V-0 or UL HB flame performance is required.
• FDA-grade or NSF 51 certified material is needed.
• A custom color or formulation is required.
• Widths up to 12” are needed.

Why Choose Bellofram Elastomers for Silicone Sponge Rectangles?

Bellofram Elastomers combines in-house silicone formulation and extrusion capabilities to manufacture custom sponge rectangles tailored to application-specific dimensions and performance requirements.

Bellofram Elastomers offers:

• Custom thickness and width combinations.
• Usable widths up to 12”.
• Continuous extruded roll material.
• Soft through firm density options.
• Closed-cell silicone sponge construction.
• Continuous temperature capability from -85°F to +400°F.
• UL 94 V-0 and UL HB flame-retardant options.
• FDA-grade and NSF 51 certified options.
• Custom colors and formulations.
• U.S.-based manufacturing and technical support.

Frequently Asked Questions About Silicone Sponge Rectangles