BISCO® RS-800 Medium
BISCO® RS-800 is a medium cellular silicone sponge with a density of 25 lb/ft³ and a compression force deflection of 11.5 psi per ASTM D1056, designed to retain the lightness of a foam while providing the enhanced sealing capability of a traditional sponge rubber. The material has a temperature range of -67°F to 392°F, passes UL 94 V-0 and UL 94 HF-1 at a third-party laboratory, and is UV and ozone resistant. RS-800 is an alternative to HT-800.
Key Properties
- Compression Force Deflection: 11.5 psi (ASTM D1056)
- Compression Set, 22 Hours @ 212°F @ 50%: 4.0% (ASTM D1056)
- Water Absorption: 1.0% (ASTM D1056)
- Density: 25 lb/ft³
- Temperature Range: -67°F to 392°F
- UL 94 V-0 / UL 94 HF-1: Pass (Meets at third party lab)
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Thickness | 1/8″, 3/16″, 1/4″ | — |
| Color | Gray | — |
| Material/Substrate | Silicone Sponge | — |
| Density | 25 lb/ft³ | — |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection | 11.5 psi | ASTM D1056 |
| Compression Set, 22 Hours @ 212°F @ 50% | 4.0% | ASTM D1056 |
| Water Absorption | 1.0% | ASTM D1056 |
| Low Temperature Brittleness | -67°F | ASTM D746 |
Thermal Properties
| Property | Value | Test Method |
| Temperature Range | -67°F to 392°F | — |
Flame & Fire Performance
| Property | Value | Test Method |
| UL 94 V-0 | Pass | Meets at third party lab |
| UL 94 HF-1 | Pass | Meets at third party lab |
Environmental Performance
| Property | Value | Test Method |
| UV Resistance | Yes | — |
| Ozone Resistance | Yes | — |
Compliance
- UL 94 V-0 — Compliant (Meets at third party lab)
- UL 94 HF-1 — Compliant (Meets at third party lab)
- Environmental seals against dust, moisture, air, and light penetration in outdoor enclosures including lighting fixtures, HVAC units, and electronic cabinets
- Vibration isolators in electronic components and transportation vehicle assemblies
- Shock absorbing cushions and gaskets requiring a lightweight, conformable silicone sponge
- General environmental sealing in enclosures requiring UL 94 V-0 and HF-1 rated materials
- Replacement or alternative sealing for HT-800 applications where sponge rubber performance in a lighter cellular format is required
Common industries: Electronics, HVAC, transportation, industrial manufacturing, outdoor enclosures.
BISCO® RS-800 is a medium-grade cellular silicone sponge in the BISCO® RS series, positioned as a direct alternative to HT-800. It is designed to combine the lightweight character of a silicone foam with the enhanced sealing performance of a traditional sponge rubber — specifically the ability to conform under lower closure forces while maintaining a durable, resilient environmental seal.
Available in 1/8″, 3/16″, and 1/4″ thicknesses, it addresses environmental sealing, vibration isolation, and shock absorption applications in outdoor enclosures, electronic cabinets, HVAC units, and transportation assemblies.
The material achieves a compression set of 4.0% at 22 hours, 212°F, 50% deflection per ASTM D1056, demonstrating good resistance to permanent deformation under sustained load at elevated temperature. Low temperature brittleness is rated at -67°F per ASTM D746, consistent with the full temperature range of -67°F to 392°F. Water absorption is 1.0% per ASTM D1056. UV resistance and ozone resistance are both confirmed Yes. The material exhibits temperature independency across its service range as stated on the TDS.
Compliant with UL 94 V-0 and UL 94 HF-1 (meets at third party lab).
What differentiates RS-800 from the other grades in the BISCO® RS series?
RS-800 is the medium-grade cellular silicone sponge in the RS series at 25 lb/ft³ density and 11.5 psi CFD — firmer than RS-870 (16 lb/ft³, 5 psi CFD) and softer than RS-820 and RS-840 (both 30 lb/ft³, 22.5 psi CFD). It is specifically positioned as an alternative to HT-800 and is suited to environmental sealing and vibration isolation applications where a balance of compliance and sealing force is required, without the higher deflection resistance of the firm grades.
Why is compression set critical for a cellular silicone sponge used in environmental sealing?
Compression set measures the permanent deformation a sponge retains after being held under compression at elevated temperature. For environmental seals in enclosures, a sponge that takes a high compression set gradually loses its ability to spring back against the mating flange, reducing contact force and allowing gaps to form through which dust, moisture, or air can infiltrate. RS-800's compression set of 4.0% at 22 hours, 212°F, 50% deflection per ASTM D1056 confirms that the material maintains its sealing geometry and contact force through sustained thermal and mechanical loading.
What is the temperature range for RS-800?
The temperature range is -67°F to 392°F as listed on the TDS. Low temperature brittleness is rated at -67°F per ASTM D746.
Is RS-800 suitable for flame-rated environments?
Yes. RS-800 passes UL 94 V-0 and UL 94 HF-1 at a third-party laboratory as listed on the TDS.
How should RS-800 be specified?
Specify grade (RS-800), thickness (1/8", 3/16", or 1/4"), color (Gray), applicable compliance requirements (UL 94 V-0, UL 94 HF-1), dimensional tolerances, and finished format (sheet, slit roll, or die-cut gasket).
