When it comes to gasketing materials, silicone-based products offer a combination of temperature resistance, long-term durability, and reliable sealing performance. Within the Rogers BISCO® product family, the RS series of cellular silicones—RS-720, RS-750, and RS-770—stand out as versatile silicone sponge materials designed for a wide range of sealing and cushioning applications.
What Are BISCO® Cellular Silicones?
Rogers BISCO® cellular silicones are engineered silicone sponge products. Unlike silicone foam, which typically has an open-cell structure that can allow for more air and fluid transmission, silicone sponge products are characterized by a controlled closed-cell or mixed-cell matrix. This gives sponge materials a denser feel and improved resistance to environmental ingress, while still offering compressibility.
The BISCO® RS family provides the following key benefits:
-
Temperature resistance: Retains elasticity from -60°C up to 200°C (intermittent higher exposure possible).
-
Compression set resistance: Maintains sealing integrity after repeated cycles of compression and relaxation.
-
Environmental durability: Resistant to ozone, UV, and weathering.
-
Consistency: Manufactured with tight tolerances for predictable compression-deflection values.
The RS Product Variations
Each grade of BISCO® RS material is designed for a specific balance of softness and firmness:
-
RS-720 (Soft)
-
The most compliant option in the series.
-
Excellent for delicate sealing applications where low closure force is critical.
-
Ideal for lightweight enclosures, fragile components, or seals that must accommodate wide tolerances.
-
-
RS-750 (Medium)
-
The “middle ground” option offering both resilience and support.
-
Performs well in gasketing where moderate compression is expected.
-
Suitable for enclosures, access panels, and applications where balance between cushioning and sealing is needed.
-
-
RS-770 (Firm)
-
The most rigid option, requiring higher compression force.
-
Recommended for demanding environments where robust sealing and mechanical support are priorities.
-
Often used in applications exposed to vibration or where structural rigidity of the gasket is necessary.
-
Applications of RS Silicone Sponge
Typical uses for the BISCO® RS silicone sponge series include:
-
Environmental gaskets for electronic enclosures.
-
Seals for outdoor lighting fixtures exposed to rain, dust, or UV.
-
Vibration damping pads for automotive or aerospace equipment.
-
General-purpose gasketing where temperature extremes or long-term durability are required.
Comparing Sponge vs. Foam
While both silicone foam and silicone sponge materials are widely used for gasketing, there are important distinctions:
-
Silicone Sponge (like BISCO® RS-720/750/770):
-
Denser, more uniform structure.
-
Provides stronger resistance to water and environmental ingress.
-
Typically used where sealing is more critical than cushioning.
-
-
Silicone Foam:
-
Lighter, more open structure.
-
Provides excellent cushioning, vibration isolation, and energy absorption.
-
Typically used where impact resistance or lightweight properties are prioritized.
-
Choosing between sponge and foam comes down to the specific balance of sealing versus cushioning performance.
How much to Compress?
These gaskets should be compressed anywhere from 25% to 50% to get proper sealing. That brings in the question, what thicknesses does the RS series come in? .093” to .500” is typical for these materials. You should aim for 40% higher nominal thickness to get proper sealing.
More Information for RS Series Silicone Sponge
The Rogers BISCO® RS series of silicone sponge materials—RS-720 (soft), RS-750 (medium), and RS-770 (firm)—offer engineers a highly versatile set of gasketing solutions. With superior resistance to heat, UV, and environmental exposure, these materials provide long-term durability across industries such as electronics, lighting, automotive, and aerospace. For applications that demand robust sealing performance with options for varying firmness, the RS sponge family is a dependable choice. NEDC does custom die-cutting, and waterjet cutting.