Cellular Sheet

Medium Density Closed Cell Silicone Foam Sheet

Silicone foam sheet is a lightweight, flexible, closed‑cell material engineered for thermal insulation, cushioning, gasketing, and vibration damping. ElastaPro manufactures silicone foam sheets and rolls in medium density and multiple thicknesses for aerospace, electronics, automotive, and industrial sealing applications. Foam silicone sheet provides excellent compression recovery, high‑temperature stability, and long‑term resistance to UV, ozone, and environmental exposure.

ESS12M Data Sheet: Medium Density Silicone Foam

ElastaPro makes foam silicone sheet that is gray in color and has a smooth finish on both sides. The standard width is 19”, and the maximum roll length is 33”. We can slit foam silicone sheet at various widths, and we can apply a pressure sensitive adhesive (PSA) to help you speed installation. ElastaPro also provides foam silicone rolls instead of pre-cut sheets.

Note: For applications requiring a firmer, more structural elastomer, see our solid silicone sheet. For softer, more compressible gasketing, explore silicone sponge sheet.

Technical Data: Medium Density Closed Cell Silicone Foam 

ElastaPro’s medium density closed cell silicone foam is an excellent material for gasket applications. It is grey in color and has a smooth finish.

PROPERTIES TEST METHOD TYPICAL VALUES
Density, lbs/cu.in. ASTM D3574 013
Compression Deflection, psi ASTM D1056-78 7-11
Hardness ASTM D2240 15±5 ShoreC
Compression Set 22 hrs. @ 212℉ 1%
Water Absorption, % Internal test 24hrs <5
Temperature Range ºF SAE J2236 -55 to 400º
Tensile Strength, psi ASTM D412 >36
Elongation, % ASTM D412 >70
Flammability UL 94 V0
Permittivity ASTM D150 1.39 C²/(N·M²)
Dielectric Strength ASTM D149 1.6 KV/mm
Flame Diffusion Index ASTM E162 ＜25
Smoke density (4min/Ds) ASTM E662 ＜50
Gas Emission Level SMP-800C PASS

Several material properties make closed cell medium-density silicone foam sheets uniquely suitable for industrial and aerospace sealing:

  • Compression Deflection: Indicates how easily the foam compresses—important for sealing under low clamping force.
  • Compression Set Resistance: Measures the foam’s ability to recover after compression cycles.
  • Thermal Conductivity: Provides thermal insulation for temperature-sensitive assemblies.
  • Flame Resistance: Many grades meet UL 94 V-0 or equivalent aerospace standards.
  • Electrical Insulation: Excellent dielectric strength for electronic enclosures.
  • Dimensional Stability: Withstands expansion or contraction across temperature swings.

These properties ensure consistent performance, long seal life, and reduced maintenance for systems that experience vibration, temperature variation, and environmental stress.

Silicone Foam Sheet vs. Silicone Sponge Sheet

Silicone foam sheet is produced using a controlled expansion process that creates a uniform closed‑cell structure. This structure traps sealed air pockets throughout the material, resulting in a lightweight, compressible elastomer with excellent thermal and environmental sealing properties.

Unlike silicone sponge—which is also closed‑cell but denser—silicone foam is softer, more flexible, and better suited for cushioning, insulation, and low‑force sealing applications.

Property Silicone Foam Silicone Sponge
Structure Closed‑cell Closed‑cell
Density Lower Higher
Compression Very soft, compressible Soft–medium
Thermal Insulation Excellent Good
Best Use Cushioning, insulation, low‑force sealing Gasketing, enclosure sealing
Water Absorption Minimal Minimal
Applications Aerospace, electronics, thermal pads HVAC, outdoor enclosures, industrial gaskets

If you need a firmer sealing material, consider silicone sponge sheet.

If you need a non‑cellular elastomer, see solid silicone sheet.

Closed Cell Silicone Foam vs. Open Cell Silicone Foam

Closed‑cell and open‑cell silicone foams differ primarily in cell morphology, which drives their mechanical, thermal, and sealing behavior.

Closed‑cell silicone foam contains discrete, gas‑filled cells with intact walls. This structure limits air and moisture permeability, enabling predictable compression behavior and low water absorption. Under load, closed‑cell foams exhibit higher compressive strength and lower compression set, making them suitable for environmental sealing where IP‑rated performance or pressure retention is required. Their reduced gas diffusion also improves stability under thermal cycling, since cell pressure changes are constrained.

Open‑cell silicone foam consists of interconnected cells that allow air movement throughout the material. This yields lower density, lower compressive force deflection, and higher conformability. Because air can escape during compression, open‑cell foams maintain more linear stress–strain curves at low deflection and are effective for vibration damping, acoustic absorption, and gap filling where sealing against liquids is not the primary requirement. However, the interconnected structure increases water uptake and reduces suitability for outdoor or immersion‑exposed assemblies unless encapsulated.

In practice, closed‑cell foams are selected for gasketing, enclosure sealing, and thermal barriers requiring controlled compression. Open‑cell foams are used where energy absorption, airflow, or acoustic performance dominate the design constraints.

Parameter Closed Cell Silicone Foam Open Cell Silicone Foam
Cell Structure Discrete, sealed gas‑filled cells

 

 Interconnected, permeable cell network
Air / Moisture Permeability Very low; limits fluid and vapor ingress High; allows airflow and moisture penetration
Density Typically higher due to intact cell walls Lower; reduced mass per unit volume
Compression Behavior Higher compressive strength; non‑linear response as cells pressurize Lower compressive force; more linear response as air escapes
Compression Set Generally lower; retains thickness after repeated cycling Higher; more permanent deformation over time
Water Absorption Minimal; suitable for splash, rain, and immersion‑adjacent environments Significant unless encapsulated; not suited for liquid sealing
Thermal Stability Stable under thermal cycling; cell pressure changes constrained Stable elastomerically, but airflow can accelerate heat transfer
Sealing Performance Effective for environmental, dust, and liquid sealing Not appropriate for liquid sealing; suitable for breathable barriers
Energy / Vibration Absorption Moderate; stiffness limits damping at low loads High; air movement and lower modulus improve damping
Typical Applications Gaskets, enclosure seals, thermal barriers, IP‑rated assemblies Acoustic pads, vibration isolators, gap fillers, breathable cushions

 

Material Properties: Foam Silicone Sheet

Foam silicone combines the desirable features of silicone rubber—thermal resistance, flexibility, and chemical stability—with the cushioning of a foam.

  • Wide temperature range: -55°C to +200°C continuous, short-term up to +230°C.
  • Low compression set: Excellent recovery, even after long-term compression.
  • Lightweight construction: Reduces component weight while maintaining structural integrity.
  • Environmental durability: Resistant to UV, ozone, and weathering.
  • Chemical compatibility: Performs well in contact with oils, coolants, and process chemicals.
  • Dielectric insulation: Maintains electrical isolation in sensitive assemblies.
  • Dimensional stability: Retains shape and thickness over long-term service.

These features make foam silicone sheet materials an essential component for high-performance gaskets and thermal insulation systems in demanding industries.

Benefits of Medium Density Closed Cell Silicone Foam Sheet

Choosing a medium density closed cell silicone foam sheet provides several performance advantages:

  • Superior sealing: Prevents moisture, air, and dust intrusion in enclosures and housings.
  • Excellent compression and recovery: Maintains sealing force and shape across multiple cycles.
  • Thermal stability: Reliable performance from -55°C to +200°C.
  • UV and ozone resistance: Long service life in outdoor or exposed environments.
  • Low outgassing: Suitable for electronics, optics, and aerospace.
  • Chemical resistance: Tolerates automotive fluids, lubricants, and cleaning agents.
  • Durability: Maintains mechanical and sealing properties after long-term stress and vibration.

For engineers designing IP-rated or weatherproof assemblies, medium density closed-cell silicone foam sheets provide consistent sealing performance under dynamic conditions.

Common Applications for ElastaPro’s Silicone Foam Sheet

Silicone foam is used across aerospace, electronics, HVAC, automotive, and outdoor sealing environments, including:

  • Aerospace insulation and flame‑retardant gasketing
  • Electronics cushioning and thermal isolation
  • HVAC door and access panel seals
  • Outdoor electrical enclosures
  • LED lighting gaskets
  • Automotive thermal barriers
  • Vibration damping and shock absorption
  • Medical and laboratory equipment

Foam silicone sheets, especially in medium-density closed-cell grades, are used in a wide range of engineering applications:

  • Electronics and Enclosures: Weatherproof gaskets for EMI/RFI shielding and IP-rated sealing.
  • Automotive and Transportation: Lighting gaskets, door seals, and vibration isolators exposed to heat and UV.
  • Aerospace and Defense: Lightweight, flame-resistant seals compliant with FAR 25.853 and MIL-DTL specifications.
  • Industrial Equipment: Environmental seals and vibration pads for pumps, compressors, and control panels.
  • Energy and Power Systems: Battery insulation, inverter seals, and shock absorption.
  • Medical and Life Sciences: Biocompatible cushioning and seals for reusable equipment.

In all these applications, medium density closed cell silicone foam sheet provides a durable, flexible, and long-lasting sealing solution that withstands mechanical and environmental challenges.

For medical‑grade or biocompatible materials, see USP Class VI Silicone Sheet.

Available Densities, Thicknesses, and Formats for Silicone Foam Rubber Sheet

ElastaPro offers silicone foam rubber sheet in:

  • Densities: Medium
  • Thicknesses: 1/16″ to 1″ (custom thicknesses available)
  • Sheet sizes: Standard and custom
  • Continuous rolls: For converters and high‑volume production
  • Custom fabrication: Stripping, slitting, die‑cutting, and waterjet cutting

For continuous‑length materials, explore silicone rolls.

Summary of Technical Specifications

This table summarizes the technical specifications for medium-density closed-cell silicone foam rubber sheet.

Property Typical Values
Cell Structure Closed‑cell
Density Options Medium
Temperature Range –60°C to +200°C
Compression Set Low
Flame Rating UL 94 V‑0 (optional)
Water Absorption Minimal
Available Thicknesses 1/16″ to 1″
Formats Sheets and Rolls

FAQ: Closed Cell Silicone Foam Sheet

Is silicone foam closed‑cell or open‑cell?

Silicone foam is typically closed‑cell, providing excellent moisture and environmental resistance.

What is silicone foam used for?

It’s commonly used for insulation, cushioning, gasketing, vibration damping, and thermal management.

Is silicone foam heat resistant?

Yes. Silicone foam performs reliably from –60°C to +200°C.

Is silicone foam the same as silicone sponge?

No. Silicone foam is softer and more compressible; silicone sponge is denser and better for structural gasketing.

Is silicone foam flame‑retardant?

Flame‑retardant grades such as UL 94 V‑0 and FAR 25.853 are available.

Does silicone foam absorb water?

Closed‑cell silicone foam absorbs minimal water, making it suitable for outdoor use.

Request a Quote for Silicone Foam Rubber Sheet

ElastaPro manufactures silicone foam sheets and rolls engineered for insulation, cushioning, and sealing in demanding environments.

Request a quote today to discuss densities, thicknesses, and custom‑cut options for your application.