BISCO® HT-800 Medium
BISCO® HT-800 is a medium-firmness closed cell silicone foam engineered to combine the lightness of foam with the enhanced moisture sealing capability of sponge rubber. Rated from −67°F to 392°F, HT-800 delivers 9.7 psi compression force deflection at 25% and 2.4% compression set (22 hrs @ 212°F, 50%), supporting reliable long-term performance in demanding outdoor and industrial sealing applications.
Key Properties
- Compression Force Deflection @ 25%: 9.7 psi (67 kPa) typical; spec 6–14 psi (41–97 kPa)
- Compression Set: 2.4% typical; spec <5% (22 hrs @ 212°F, 50%)
- Density: 22 lb/ft³ (352 kg/m³) typical
- Water Absorption: 0.5%; spec <5%
- Thermal Conductivity: 0.076 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 | 22 lb/ft³ (352 kg/m³) typical | — |
| Thermal Conductivity | 0.076 W/m°K | ASTM C518 |
| Water Absorption | 0.5%; spec <5% | Internal (24 hrs, 2″ below surface) |
| Thicknesses Available | 0.031″, 0.063″, 0.094″, 0.125″, 0.188″, 0.250″, 0.375″, 0.500″ | — |
| Colors | Black, Gray, Red | — |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection @ 25% | 9.7 psi (67 kPa) typical; spec 6–14 psi (41–97 kPa) | ASTM D1056 |
| Compression Set (22 hrs @ 212°F, 50%) | 2.4% typical; spec <5% | ASTM D1056 |
Flame & Fire Performance
| Property | Value | Test Method |
| Flame Resistance | V-0 | 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 | — |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Strength | 75 V/mil | ASTM D149 |
| Dielectric Constant @ 1 kHz | 1.7 | ASTM D150 |
| Dissipation Factor @ 1 kHz | 0.005 | ASTM D150 |
| Dry Arc Resistance | 125 sec | ASTM D495 |
| Volume Resistivity | 10¹⁴ Ω·cm | ASTM D257 |
Outgassing (ASTM E595)
| Property | Value | Test Method |
| Total Mass Loss (TML) | 0.98% | ASTM E595 |
| Collected Volatile Condensable Materials (CVCM) | 0.25% | ASTM E595 |
| Water Vapor Regain (WVR) | 0.03% | ASTM E595 |
Compliance
- UL 94 V-0 — Compliant (File E83967)
- FMVSS-302 — Compliant
- FDA 21 CFR 177.2600 — Compliant (Gray grade only)
- AMS3195 — Compliant
- Outdoor communication enclosure and electronic cabinet gasketing
- Lighting fixture and HVAC unit environmental seals
- Fine dust particle and wind-driven rain sealing
- Shock absorption and vibration isolation in electronic components
- Transportation vehicle vibration isolation and sealing
Common industries: electronics, telecommunications, lighting, transportation, and industrial equipment.
HT-800 is the core medium-firmness grade in the HT-800 series, embodying the transition from soft and conformable to firm and durable. Its compact cell structure and unique formulation provide enhanced sealing against fine dust particles, wind-driven rain, and fire — performance characteristics more typically associated with sponge rubber, delivered in a lightweight foam form. Excellent memory and low stress relaxation reduce long-term maintenance costs associated with gasket failure from compression set and softening.
HT-800 is one of the most widely specified BISCO grades for outdoor communication enclosures, electronic cabinets, and lighting fixtures. It also delivers shock absorption and vibration isolation for electronic components and transportation vehicles. Compliant with UL 94 V-0, FMVSS-302, FDA 21 CFR 177.2600 (Gray grade), and AMS3195.
What differentiates HT-800 from other HT-800 series grades?
HT-800 is the medium-firmness grade at 9.7 psi CFD typical, offering the best balance of conformability and sealing capability in the series. It is the most widely specified grade for general-purpose outdoor and electronic enclosure gasketing.
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-800 suitable for regulated environments?
Yes. The Gray grade of HT-800 is compliant with FDA 21 CFR 177.2600. It also meets UL 94 V-0, FMVSS-302, and AMS3195 standards.
How should this material be specified?
Specify grade (HT-800), thickness, color (note FDA compliance is Gray only), compliance requirements, dimensional tolerances, and finished format.
