Silicone Foams Guide

The unique qualities of silicone foam make it a significant material in numerous sectors, including aerospace, automotive, construction, and electronics.

What is Silicone Foams?

Silicone foam products are produced from platinum-cured, liquid silicone rubber. The raw compound is expanded and distributed on a continuous casting line, then heat cured.

The expansion process is managed to provide a range of products with varied densities, softness/firmness, and cell architectures. Silicone foam materials often have smooth skin on one or both sides due to the casting process.

The final product has lightweight, flexible, and has a homogeneous cell structure that makes it appropriate for a number of applications. comprising thermal and acoustic insulation, sealing and gaskets, cushioning, and vibration dampening.

What is Silicone Foam?​

Open-cell Vs Closed-cell Silicone Foam Structure

Silicone foam is available in both open-cell and closed-cell foam structure

  • Open cell foam structure permits excellent absorption of water, moisture, and dust – making it perfect in a conventional sponge used for washing automobiles.

  • Closed cell foam structure doesn’t accommodate for the absorption of water, moisture, or dust – making it excellent in sealing applications where water and dust need to be kept out. This kind is intrinsically hydrophobic (repels water) (repels water).
Silicone Foam Gaskets and Silicone Foam Cushioning

Benefits of Silicone Foam

  • Wide working temperature – silicone foam has a temperature range of -67°F to 392°F (-55°C to 200°C).
  • Easily fabricated into various types of foam gaskets, pads, tapes and sealing profiles
  • Available in various densities and shapes
  • Excellent performance on sealing, cushioning, soundproofing
  • UV and ozone resistance - silicone goods have exceptional UV and ozone resistance due in part to their inorganic backbone. This gives a long-lasting performance.
  • UL gasket - most silicone foam materials sold by LGDsilicone Elastomerics are UL 94 flame certified and UL 50 and UL 50E rated for the gasket.

Properties of Silicone Foam

A. Physical Properties

  • Closed Cell Foam Material
  • Good performance at severe temperatures
  • Excellent fire resistance
  • Low compression set
  • UV and ozone resistance

B. Chemical Properties

Mechanical PropertiesMetricEnglish
Hardness, Shore A3.0 - 623.0 - 62
Hardness, Shore OO40 - 7040 - 70
Tensile Strength, Ultimate0.0552 - 2.80 MPa8.00 - 406 psi
Tensile Strength, Yield0.172 - 1.24 MPa25.0 - 180 psi
Elongation at Break49 - 300 %49 - 300 %
Compressive Yield Strength0.00800 - 0.170 MPa1.16 - 24.7 psi
Compression Set0.00 - 80 %0.00 - 80 %

Applications of Silicone Foam

  • Automotive Foam Gaskets, Pads, Tapes
  • Industrial Foam Parts
  • Medical Devices
  • Flooring Underlay
  • Manufacturing Equipment
  • Sealing and Cushioning Applications
  • Indoor lighting (dust gasket, UL 94V-0)
  • Instrumentation (vibration dampening)

Silicone Sponge Vs. Silicone Foam

While both silicone sponge and silicone foam have superior sealing qualities at increased temperatures, there are small variances in the materials. Silicone sponge is compounded and combined on a 2-roll mill and then cured in an oven. Silicone foam is manufactured from a liquid silicone which is extruded and cured in an over. Both are cellular.

Raw MaterialGum-based silicone, mixed and cured in an ovenLiquid silicone extruded and cured in an oven
Min Max Use Temp

-73oC +260oC

-100oF + 500oF

-51oC +200oC

-67oF + 392oF

FlammabilityUL 94 HBF (horizontal burn formula is available V22-300)UL 94 V-0 Vertical burn - better flame rating than sponge
Compression SetGood (a lower compression set formula is available V22-210)Better compression set than a sponge
Tensile StrengthHigh tensile strength; higher material weightLower tensile strength than a sponge; lower material weight. Easier to tear by hand.

Soft Silicone Sponge = 21-30 PCF (pound/cubic ft) typical

Medium Silicone Sponge = 29-33 PCF typical

Firm Silicone Sponge = 40 PCF typical

Soft Silicone Foam = 12 PCF typical(pound/cubic ft)

Medium Silicone Foam = 22 PCF typical

Compression Deflection

Soft Silicone Sponge = 5-9 PSI typical

Medium Silicone Sponge = 6-14 PSI typical

Firm Silicone Sponge = 12-20 PSI typical

Soft Silicone Foam = 3 PSI typical

Medium Silicone Foam = 9 PSI typical

Note: The information provided is for reference and the user must determine if a particular

Silicone sponge tends to be greater in density, have stronger rip strength, and has a higher usage temp (up to 500F compared to 392F for silicone foam) (up to 500F compare to 392F for silicone foam) Essentially silicone sponge has greater physical and mechanical qualities than silicone foam.

Silicone foam tends to be softer, lower in density, and has lower compression set properties. Since it includes more air, it provides superior thermal insulation. Silicone foam also provides greater flame retardant qualities which are important in aeronautical applications. Neither substance absorbs much water, therefore silicone "sponge" is frequently a confused descriptor.