Silicone Foam Sheet: Medium Density, Closed Cell
UL 94 V-0 Flame-Resistant Foam for High-Stakes Thermal Barriers
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.
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.
Need Silicone Foam Sheet or Slit Rolls?
We supply continuous rolls and pre-cut sheets with low minimums and fast lead times.
Request a Quote (RFQ)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.
- High & Low temperature Resistant
- High Compressibility
- Low Compression Set
- UV / Ozone Resistant
- AMS3195
- UL 94 V-0 Flammability
| 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 Sheet vs. Open Cell Silicone Foam Sheet
Closed‑cell and open‑cell silicone foams differ primarily in cell morphology, which drives their mechanical, thermal, and sealing behavior.
Closed‑cell silicone foam sheet 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 sheet 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
- 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 |
FAQs: 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 (RFQ)