Specification Grade Silicones

ASTM D1056 Cellular Silicone Sheeting: Sponge & Foam

ElastaPro manufactures premium ASTM D1056 cellular silicone sheeting, including closed-cell silicone sponge and lightweight silicone foam products engineered for high-performance sealing, cushioning, and thermal insulation. The ASTM D1056 specification is the primary recognized standard for flexible cellular materials—defining cell structure, density, compression deflection, and fluid resistance parameters across industrial, aerospace, and defense supply chains.

Whether your application requires soft compression sealing for environmental enclosures or flame-retardant cushioning for transit equipment, ElastaPro cellular silicone provides outstanding resilience, weatherability, and compression set resistance. All products are Made in the USA at our Santa Fe Springs, California facility under an AS9100D and ISO 9001:2015 certified quality management system and supplied with complete Certificates of Analysis (COA).

Need ASTM D1056 Silicone Sponge or Foam Rolls?

We supply continuous roll stock, pre-cut sheets, and custom-slit rolls with low minimum order quantities, optional pressure-sensitive adhesives (PSA), and rapid turnarounds.

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Understanding ASTM D1056 Classification Codes

ASTM D1056 uses a line callout system to designate cellular material types, performance suffix requirements, and compression deflection ranges:

Callout Prefix Type & Grade Description Primary Physical Characteristics
Type 2, Class A Closed-Cell Silicone Sponge (Non-Oil Resistant) General-purpose thermal insulation and weather-sealing
Type 2, Class B Closed-Cell Silicone Sponge (Oil Resistant) High fluid and chemical resistance for industrial environments
Grade 2A1 / 2B1 Soft Density Cellular Silicone Low compression force deflection for delicate housings
Grade 2A2 / 2B2 Medium Density Cellular Silicone Balanced compressibility and sealing force for outdoor enclosures
Grade 2A3 / 2B3 Firm Density Cellular Silicone High load-bearing support and gap filling under compressive force

Key Advantages of ASTM D1056 Cellular Silicone

  • Broad Thermal Range: Maintains elastomeric compressibility and flexibility across extreme temperatures from sub-zero conditions down to -100°F (-73°C) up to elevated temperatures exceeding +400°F (+204°C).
  • Exceptional Weather & UV Resistance: Highly resistant to ozone oxidation, severe outdoor weathering, and ultraviolet radiation, preventing gasket breakdown over extended service life.
  • Low Compression Set: Resists permanent deformation under continuous loads to maintain long-term dust, air, and moisture seals.
  • Converter Ready: Easily converted via die-cutting, knife cutting, or waterjet cutting, and available with factory-applied Pressure Sensitive Adhesive (PSA) backings.

Target Industry Applications

  • Enclosure Weather-Sealing: NEMA and IP-rated environmental gaskets for outdoor electrical and telecom enclosures.
  • Transportation & Mass Transit: Flame-retardant interior sealing and thermal insulation pads meeting transit safety standards.
  • HVAC & Industrial Equipment: Air-handling unit seals, door gaskets, and dampening pads for industrial machinery.
  • Aerospace & Defense: Lightweight thermal barrier padding and vibration isolation strips for defense avionics housings.

Note: ElastaPro also provides other specification grade silicones for these and other applications.

Frequently Asked Questions About ASTM D1056 Silicone

What is ASTM D1056, and how does it apply to silicone materials?

ASTM D1056 is a standard specification established by ASTM International for flexible cellular materials, covering sponge and expanded rubber products. When applied to silicone, it defines physical requirements such as density, water absorption, low-temperature flexibility, and compression deflection—allowing engineers to specify exact closed-cell sponge or foam hardness grades for sealing applications.

What is the difference between solid silicone sheet and ASTM D1056 cellular silicone?

Solid silicone sheet is a dense, unexpanded elastomer used primarily for high-durometer, high-tensile strength flange gaskets. ASTM D1056 cellular silicone (sponge or foam) contains internal void structures, making it significantly lighter, softer, and more compressible. Cellular silicone requires far less closing force to create an environmental seal, making it ideal for thin-gauge metal or plastic enclosures.

Can ElastaPro supply ASTM D1056 silicone with pressure-sensitive adhesive (PSA)?

Yes. ElastaPro ASTM D1056 silicone sponge and foam sheeting can be supplied with factory-applied pressure-sensitive adhesive (PSA) backings. Options include acrylic adhesives for general bonding or high-temperature silicone-based adhesives, protected by a peel-off release liner for easy gasket assembly.

Does ASTM D1056 silicone sponge absorb water?

Standard ASTM D1056 Type 2 closed-cell silicone sponge is designed to minimize water absorption. Because the individual cells are completely sealed from one another, closed-cell silicone sponge prevents fluid ingress under normal environmental sealing conditions, passing strict water absorption limits defined by the ASTM D1056 standard.