BISCO® HT-870 Soft
BISCO® HT-870 is a soft, medium-density closed cell silicone foam engineered as a firmer and denser alternative to BF-1000, maintaining low closure force and high conformability while delivering enhanced sealing performance. Rated from −67°F to 392°F, HT-870 achieves 1.6% compression set (22 hrs @ 212°F, 50%) and meets UL 94 V-0 and HF-1 flame standards.
Key Properties
- Compression Force Deflection @ 25%: 3.8 psi (26 kPa) typical; spec 1–7 psi (7–48 kPa)
- Compression Set: 1.6% typical; spec <5% (22 hrs @ 212°F, 50%)
- Density: 15 lb/ft³ (240 kg/m³) typical
- Water Absorption: 0.5%; spec <10%
- Thermal Conductivity: 0.06 W/m°K
- Recommended Service Temperature: −67°F to 392°F
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Material | Closed Cell Silicone Foam | — |
| Density | 15 lb/ft³ (240 kg/m³) typical | — |
| Thermal Conductivity | 0.06 W/m°K | ASTM C518 |
| Water Absorption | 0.5%; spec <10% | Internal (24 hrs, 2″ below surface) |
| Thicknesses Available | 0.063″, 0.094″, 0.125″, 0.188″, 0.250″, 0.375″, 0.500″ | — |
| Colors | Black, Red | — |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection @ 25% | 3.8 psi (26 kPa) typical; spec 1–7 psi (7–48 kPa) | ASTM D1056 |
| Compression Set (22 hrs @ 212°F, 50%) | 1.6% typical; spec <5% | ASTM D1056 |
Flame & Fire Performance
| Property | Value | Test Method |
| Flame Resistance | V-0 ; HF-1 | UL 94 (File E83967) |
| Flame Spread Index (Is) | <35, Flaming Mode | ASTM E162 |
| Smoke Density (Ds) @ 1.5 Minutes | <100, Flaming Mode | ASTM E662 |
| Smoke Density (Ds) @ 4 Minutes | <200, Flaming Mode | ASTM E662 |
| Burn Length | <100 mm/min | FMVSS 302 |
Thermal & Environmental Performance
| Property | Value | Test Method |
| Recommended Use Temperature | −67°F to 392°F (−55°C to +200°C) | Internal |
| Low Temperature Flexibility | Pass at −67°F (−55°C) / 3 min | ASTM D746 |
| Low Temperature Brittleness | Pass at −67°F (−55°C) / 5 hrs | ASTM D1056 |
| UV Resistance | Yes | — |
| Ozone Resistance | Yes | — |
Compliance
- UL 94 V-0 — Compliant (File E83967)
- UL 94 HF-1 — Compliant (File E83967)
- FMVSS-302 — Compliant
- Environmental sealing of outdoor enclosures requiring low closure force
- Electronics cushioning and shock protection
- Vibration isolation in electronic components and transportation vehicles
- Dust and moisture seals in lighting fixtures and HVAC equipment
- Thermal insulation in assemblies requiring soft, conformable gap filling
Common industries: electronics, transportation, lighting, HVAC, and industrial equipment.
HT-870 is a medium-soft closed cell silicone foam positioned between BF-1000 and HT-800 in the BISCO cellular foam series. It is a firmer, denser version of BF-1000 that retains the low closure force and conformability characteristics of the softer BF grades while simultaneously providing enhanced sealing capabilities more typical of sponge rubber grades. Its patented chemistry and cell structure deliver excellent memory and low stress relaxation for long-term gasket performance.
HT-870’s compressibility and softness allow it to conform to variable-width gaps and irregular surfaces across a wide range of operating environments. Its resistance to UV, ozone, and extreme temperatures, combined with UL 94 V-0 and HF-1 flame compliance, makes it well-suited for outdoor enclosures, electronics, and transportation applications.
Compliant with UL 94 V-0, UL 94 HF-1, and FMVSS-302.
What differentiates HT-870 from other HT-800 series grades?
HT-870 is the softest grade in the HT-800 series at 3.8 psi CFD typical, positioned between BF-1000 and HT-800. It is the preferred choice when low closure force and conformability are required alongside enhanced sealing versus the BF grades.
Why is compression set critical?
Compression set measures long-term recovery after sustained compression. Lower values indicate better sealing force retention over the life of the application, reducing maintenance costs from gasket failure.
What is the operating temperature range?
−67°F to 392°F (−55°C to +200°C)
Is HT-870 suitable for regulated environments?
Yes. HT-870 meets UL 94 V-0 and HF-1 flame ratings and FMVSS-302, supporting use in electronics and transportation applications with flame performance requirements.
How should this material be specified?
Specify grade (HT-870), thickness, color, compliance requirements, dimensional tolerances, and finished format.
