Silicone foam vs Silicone Sponge. What’s the Best Option for Your Application?
When designing components that require advanced sealing, cushioning, or protection in high temperature, extreme environment, and FDA safe applications, it is likely to encounter a choice between using silicone foam and silicone sponge. Both materials, while similar in their silicone base, differ in structure, properties, and ideal applications. Luckily, both can be combined with pressure sensitive adhesive (PSA) tape for applications where attachment or a third hand is required. There are nuances to each material and choosing one over the other can make a big difference in terms of performance in demanding industrial settings.
The Basics of Silicone Foam and Silicone Sponge
Let’s start with the basics of each material. Silicone foam and silicone sponge are both engineered materials that share an inorganic synthetic polymer foundation, comprised of mostly polysiloxane, that is known for its exceptional durability, high-temperature resistance, and chemical resilience. Both materials excel in applications where longevity, durability, and environmental resistance are required, which can include automotive, aerospace, electronics, medical devices, industrial applications, and more.
Silicone Foam is made into an open-cell structure, silicone foam is created with interconnected cellular structure that allows the passage of liquids and air throughout the material, resulting in a lightweight, flexible product with breathable properties. This structure allows it to provide excellent thermal and acoustic insulation while remaining compressible and incredibly resilient.
Silicone Sponge, in contrast, silicone sponge is a closed-cell material, offering superior resistance to water, air, and gas ingress. With a more rigid structure, silicone sponge provides very good compression set resistance when compared with many closed cell foams, making it ideal for environmental sealing applications. Its closed-cell design offers enhanced durability in extreme environments.
The Defining Properties of Silicone Foam
Silicone foam excels in providing cushioning and insulation, making it ideal for high performance sealing, cushioning, and protection. Its cellular structure allows for airflow and slight moisture absorption, making it excellent when rapid foam recovery or particle ingress resistance is critical.
The key properties of silicone foam include:
High-temperature resistance: capable of withstanding temperatures up to 400°F, it can be used in demanding environments.
Fire resistance and low smoke toxicity: silicone foam is often flame retardant, contributing to its safe usage in enclosed spaces.
Shock absorption and flexibility: the foam’s elasticity provides excellent energy absorption, making it suitable for vibration-sensitive applications.
Foam Resilience: compression set resistance and overall foam resilience is best in class. Silicone foam can be compressed over 50% of its thickness for significant periods of time and will return to its original thickness with almost no degradation.
Thermal and acoustic insulation: the material’s structure offers reliable thermal and sound insulation.
What are the pros of silicon foam? The material excels in:
Providing thermal and acoustic insulation, making it suitable for soundproofing and temperature regulation.
Being lightweight and compressible with strong rebound, enhancing its effectiveness in cushioning and shock absorption applications.
Being flame resistant with low smoke emission, essential for use in critical industries like aerospace.
FDA ratings, which enable the foam to be used in challenging food contact or medical diagnostic device applications.
The drawbacks of silicone foam include:
Its open cell structure means it is not suited for environments needing complete moisture or gas sealing.
Being less resistant to wear compared to silicone sponge, especially in environments where tear and tensile resistance are required.
When to Use Silicone Foam
Silicone foam is ideal in applications where insulation (thermal or acoustic) and shock absorption are essential. Typical use cases include:
Automotive and Aerospace: resilient gasketing for electronics, dashboards, and vibration control.
HVAC: effective thermal insulation in heating and cooling systems.
EV Batteries: creating housing barriers
Electronics: thermal insulation and shock absorption for delicate components.
Medical: the material can provide shock and vibration dampening in sensitive equipment.
The Defining Properties of Silicone Foam Sponge
Silicone sponge is a closed-cell material known for its superior sealing and environmental resistance. This structure blocks air, water, and gas, making it ideal for applications that require high resistance to external elements.
The key properties of silicone sponge include:
Enhanced environmental resistance: withstanding UV rays, ozone, and harsh weather conditions, silicone sponge is ideal for outdoor applications.
Excellent compression set resistance: while compression set resistance is not as good as silicone foam, silicone sponge is best in class when it comes to closed cell foams for retaining its shape under sustained pressure, ideal for gaskets and seals.
Sealing capabilities: as a closed cell foam product, Silicone Sponge can create a positive seal against moisture and air.
Temperature stability: with high flame resistance and thermal stability able to withstand up to 450°F, the material offers resilience and longevity in high-heat applications.
Durability: silicone sponge is stiffer and more durable compared to silicone foam.
Silicone sponge is a material that has:
Superior sealing abilities due to its closed-cell design, which prevents moisture and gas intrusion.
Resistant to UV, ozone, and chemicals, making it ideal for outdoor and industrial applications.
Better durability and a tougher foam structure when exposed to friction or loads.
The ability to be used in outdoor applications due to its environmental resistance.
The drawbacks of using silicone sponge include:
Less flexibility when compared to silicone foam, because of its reduced suitability for shock absorption and cushioning applications.
Not being as lightweight, which may affect its use in some high-performance cushioning applications where weight is a factor.
Higher compression set vs. silicone foam.
When to Use Silicone Sponge
Silicone sponge is recommended for applications requiring extensive sealing and environmental resistance. These types of applications include:
Automotive and aerospace: seals and gaskets that resist chemicals, UV, and moisture.
Outdoor enclosures: weatherstripping and sealing for electronics and equipment.
Industrial gaskets and seals: durable gasketing solutions for applications with food, medical, and chemical exposure, or other harsh environments where water resistance, high temperature, and overall durability are important.
Sealing: any application requiring superior sealing and protection from moisture, gases, and environmental elements.
Factors to Consider When Choosing Between Silicone Foam and Silicone Sponge
Selecting between silicone foam and silicone sponge depends on the specific demands of the application:
Application Requirements: determine whether your application needs more cushioning (foam) or sealing and durability (sponge).
Environmental Conditions: while both products can handle difficult conditions, silicone sponge should generally hold up better in tough environments.
Temperature Resistance: silicone is used for high temperature applications. Silicone sponge provides a higher level of temperature resistance.
Toughness: when your application requires tensile and tear resistance, silicone sponge will provide better performance
Shape Retention: for applications where shape retention under pressure is critical, silicone foam offers superior performance.
Compression Set Resistance: silicone foam excels in applications where maintaining shape under pressure is vital. However, silicone sponge has excellent resistance compared with other closed cell foams.
Sealing Capabilities: silicone sponge is better for complete sealing against liquids and gases due to its closed-cell structure.
Thermal Conductivity: due to the open cell nature of silicone foam, it is a better thermal insulator than silicone sponge
Cushioning: silicone foam is better for cushioning and energy absorption in vibration-sensitive applications.
Silicone foam is largely preferred in applications where cushioning, thermal insulation, and flexibility are required, while silicone sponge is ideal for applications necessitating robust environmental sealing, durability, and resistance.