Silicone Foam - NS-121-med • National Silicone

NS-121 Medium Silicone Foam

Cellular Silicone Foam

NS-121 is the ideal choice for applications in industries such as automotive, aerospace, rail and transit. It is directly comparable to Rogers Bisco® HT 800 foam material and Saint-Gobain NORSEAL® F-20 Silicone Foam.

Due to its low toxicity, smoke and flame properties this material is an ideal choice for vibration management, gap filling, gasket and sealing in vehicles that includes cars, trucks, buses, planes, trains and more. This product seamlessly combines the characteristics of flexibility and resilience, which is achieved by providing the lightness of foam alongside the advanced sealing capabilities of sponge rubber creating a robust, long-lasting material solution.

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  • Highly adaptable to various applications and environments
  • Prevents stress loss over time, which is often linked to gasket failures
  • Enhanced sealing capabilities – IP67
  • Low compression set
  • Long Service Life
  • Flame retardant
  • Wide Temperature Range
  • Excellent compressibility
  • Full Range of Thicknesses
  • UV/Ozone resistant
  • Low smoke
  • Low toxicity
  • Low flame spread



  • UL 94
  • UL 50E
  • UL 157
  • UL 508
  • 21 CFR 177.2600
  • ASTM D1056 2D2
  • ASTM E 662
  • ASTM E162
  • AMS3195
  • FAR 25.853
  • Bombardier SMP 800-C



Available in – Continuous rolls or cut sheets
Thickness available (in) – 0.032 to 0.500
Roll lengths available (ft) – 25 to 50, depending on thickness
Typical roll widths (in) – 36
Surface finishing – Smooth finish, both sides
Cell structure – Closed cell
Color – Grey, Black



-67°F to +392°F  (-55°C to 200°C)



Compression deflection (25%) psi (kPa) 10.1 (69.6) ASTM D1056
Density pcf (kg/m3) 20.4 (326.8) ASTM D1056
Compression set (22h, 100°C) % < 5 ASTM D1056
Tensile strength psi (kPa) >44 (300) ASTM D412
Flammability V-0 UL-94
Flame spread Index (Is) <25 ASTM E162
Smoke density (Ds)
w/t or w/o flaming
<100 1.5 min
<200 4.0 min
<300 Max Dm
Toxic gas generation Pass SMP 800-C

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UL 94 V-0

  • UL 94 V-0 is a safety and flammability standard by Underwriters Laboratories.
  • This material is compliant with the UL 94 V-0 test standard for flammability.
  • The vertical burn test measures the self-extinguishing time of a vertically oriented polymer specimen. The test evaluates both the burning and afterglow times and dripping of the burning test specimen.
  • In order to be rated UL 94 V-0, the burning must stop within 10 seconds, no flame propagation or dripping.


UL 50E

  • UL 50E is an enclosures for electrical equipment standard by Underwriters Laboratories.
  • This material is compliant with the standard intended to be installed and used in non-hazardous indoor/outdoor locations.
  • This standard also covers additional environmental construction and performance requirements for enclosures.


UL 157 

  • UL 157 is a standard for nonmetallic gasket and seal materials by Underwriters Laboratories.
  • The general use of these gasket and seal materials is to exclude or hold within an enclosure materials that are liquid, gas, or vapor.
  • materials covered in this standard include elastomers, composite gasket material, flexible cellular material, thermoplastics and thermoplastic elastomers for specific end products.


UL 508 

  • UL 508 is industrial control equipment standard by Underwriters Laboratories.
  • The standard covers industrial control devices, and devices accessory thereto, for starting, stopping, regulating, controlling, or protecting electric motors.
  • In addition these requirements also cover industrial control devices or systems that store or process information and are provided with an output motor control function(s).


21 CFR 177.2600

  • 21 CFR 177.2600 is a specification from the U.S. Code of Federal Regulations (CFR) used by the Food and Drug Administration (FDA).
  • This material is compliant with the requirements of 21 CFR 177.2600.
  • The specification covers rubber articles intended for repeated use and may be safely used in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, subject to the provisions of this section.
  • Meaning this material is generally recognized as safe, and can be used in applications where repeated use in contact with food occurs.


ASTM D1056 2D2

  • ASTM D1056 is a specification for flexible cellular materials (sponge or expanded rubber) from the American Society for Testing and Materials.
  • This material fully passes the ASTM D1056 2D2 specification for flexible cellular materials.
  • The specification covers flexible cellular rubber products known as sponge rubber and expanded rubber, but does not apply to latex foam rubber or ebonite cellular rubber.
  • Type 2 – Closed-cell rubber.
  • Class D – Cellular rubber made from synthetic rubber can meet extreme temperature resistance −103 to 347°F (−75 to 175°C).
  • Grade 2 – For Types 1 and 2 cellular rubber, has a compression deflection range from 5 to 9 psi (34.5 to 62.1 kPa).


ASTM E 662

  • ASTM E 662 is a standard specification that defines the method for measuring the specific optical density of smoke generated by solid materials under controlled conditions of combustion or decomposition.
  • This test setup involves heating a sample material in a controlled chamber and measuring the optical density of the resulting smoke to assess its opacity.
  • Importance of Measuring Smoke Density for Safety: It affects visibility and air quality in fires, hindering evacuations and raising inhalation injury risks.
  • In regulatory compliance and material selection, materials that produce less smoke are preferred in enclosed spaces for safety during fires, making this test vital in material engineering and design.



  • ASTM E162, titled “Standard Test Method for Surface Flammability of Materials Using a Radiant Heat Energy Source,” is a specification for evaluating the flammability characteristics of different materials when exposed to radiant heat.
  • The specification covers the determination of the relative surface flammability of materials when exposed to a radiant heat energy source.
  • Primarily measures the Flame Spread Index (FSI), a number that indicates the speed of flame spread on a material’s surface under set radiant heat conditions, essential for evaluating material flammability.
  • The test is crucial for safety and compliance, especially in transportation and construction. Materials with low FSI values are safer and preferred in fire-sensitive environments.



  • AMS3195 is an aerospace material specification from SAE International Group.
  • The specification covers silicone rubber sponge in the form of sheet, strip, extrusions, and molded shapes.
  • Our medium density silicone sponge sheet is in accordance with the physical property requirements of AMS3195 test standard.
  • This product has been used typically for general applications requiring closed-cell, medium sponge rubber that will be flexible from -103 to +401 °F (-75 to +205 °C), but usage is not limited to such applications. Compression set may be high at the higher temperature.


FAR 25.853

  • FAR 25.853 is a regulation part of the Federal Aviation Regulations (FARs), specifically addressing flammability requirements for materials used in the construction of commercial aircraft.
  • The regulation mandates that materials used inside the aircraft cabin, such as seat cushions, wall panels, and flooring, must be flame-resistant and able to withstand specific fire tests.
  • It includes specific criteria and test methods for assessing the flammability of these materials, ensuring that they do not easily ignite and, if they do, that they burn slowly and self-extinguish.
  • Compliance with FAR 25.853 is critical for aircraft certification, focusing on enhancing passenger safety by minimizing the risks associated with in-flight fires.


Bombardier SMP 800-C

  • Bombardier SMP 800-C is a test protocol designed to assess the generation of toxic gases from materials used in vehicle construction when they combust.
  • It specifically measures the emissions of gases like carbon monoxide, hydrogen fluoride, nitrogen dioxide, hydrogen chloride, hydrogen cyanide, and sulfur dioxide.
  • The test establishes maximum acceptable concentrations for each gas, ensuring that emissions remain within safe limits.
  • This testing is crucial for maintaining safety in vehicle manufacturing, protecting operators and passengers from toxic gas exposure, and preventing the spread of fire.



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