BISCO® 7304 Medium
BISCO® 7304 is a medium-grade closed-cell silicone sponge that meets specification BMS 1-23, with a density of 35 lb/ft³ and a compression force deflection of 6–14 psi at 25% per ASTM D1056, available in twelve thicknesses from 0.063″ to 1.00″. The material has a temperature resistance range of -67°F to 450°F, meets BMS 1-23 and FMVSS302, and has a tensile strength exceeding 200 psi per ASTM D412. Color is Red.
Key Properties
- Compression Force Deflection @ 25%: 6–14 psi (ASTM D1056)
- Tensile Strength: >200 psi (ASTM D412)
- Elongation: 150% min (ASTM D412)
- Compression Set, 22 Hours @ 212°F: 20% (ASTM D1056)
- Density: 35 lb/ft³ (ASTM D1056)
- Temperature Resistance: -67°F to 450°F
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- Specifications
- Applications
- General Info
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Physical Properties
| Property | Value | Test Method |
| Thickness | 0.063″, 0.094″, 0.125″, 0.188″, 0.25″, 0.313″, 0.375″, 0.500″, 0.625″, 0.750″, 0.875″, 1.00″ | — |
| Color | Red | — |
| Material/Substrate | Silicone Sponge | — |
| Density | 35 lb/ft³ | ASTM D1056 |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection @ 25% | 6–14 psi | ASTM D1056 |
| Compression Set, 22 Hours @ 212°F | 20% | ASTM D1056 |
| Water Absorption | 5% | ASTM D1056 |
| Tensile Strength | >200 psi | ASTM D412 |
| Elongation | 150% min | ASTM D412 |
Thermal Properties
| Property | Value | Test Method |
| Temperature Resistance | -67°F to 450°F | — |
Flame & Fire Performance
| Property | Value | Test Method |
| FMVSS302 | Pass | — |
| BMS 1-23 | Meets | — |
Environmental Performance
| Property | Value | Test Method |
| UV Resistance | Yes | — |
| Ozone Resistance | Yes | — |
Compliance
- FMVSS302 — Compliant (Pass)
- BMS 1-23 — Compliant (Meets)
- Flame resistant sealing and gasketing in Boeing-specified aerospace assemblies requiring BMS 1-23 compliance
- Automotive sealing and gasketing components requiring FMVSS302 flame compliance where the Red color designation is required for part identification
- Aerospace and industrial sealing applications requiring the combination of BMS 1-23 compliance, 450°F upper temperature resistance, and low compression set (20%)
- High-strength flame resistant gaskets requiring tensile strength exceeding 200 psi in a medium-grade closed-cell silicone sponge
- Flame resistant sealing across aerospace, defense, and automotive markets requiring a wide thickness range from 0.063″ to 1.00″ in a BMS 1-23 qualified material
Common industries: Aerospace, automotive, defense, industrial manufacturing.
BISCO® 7304 is a medium-grade closed-cell silicone sponge in the BISCO® flame resistant series, specifically formulated to meet Boeing Material Specification BMS 1-23. It is available in Red — the only red grade in the BISCO® flame resistant sponge series — and in twelve thicknesses from 0.063″ to 1.00″, matching the broadest thickness range available in the series.
With an upper temperature resistance of 450°F, it shares the highest thermal rating in the series alongside 7330, and achieves the lowest compression set in the series at 20% at 22 hours, 212°F per ASTM D1056 — substantially better than the 35% reported for 7330, 7430, and 7130.
Tensile strength exceeds 200 psi per ASTM D412, matching 7430 as the highest in the series, and elongation is 150% minimum. Water absorption is 5% per ASTM D1056. The material passes FMVSS302 and meets BMS 1-23. 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 FMVSS302 and BMS 1-23.
What differentiates BISCO® 7304 from other grades in the BISCO® flame resistant silicone sponge series?
7304 is distinguished by three characteristics unique to this grade in the series: it is the only grade in Red, it is the only grade meeting BMS 1-23 (versus BMS 1-60 for the other grades), and it achieves the lowest compression set in the series at 20% at 22 hours, 212°F — substantially better than the 35% recorded for 7330, 7430, and 7130. It also shares the highest upper temperature resistance in the series at 450°F (alongside 7330) and the highest tensile strength (>200 psi, alongside 7430).
Why is compression set critical for a BMS 1-23 silicone sponge used in aerospace sealing?
In aerospace sealing applications subject to sustained pressure, thermal cycling, and long service intervals between maintenance access, compression set determines whether the gasket maintains its sealing geometry and contact force over the service life of the assembly. A high compression set means the material does not recover its original thickness when the flange load is released or redistributed, reducing sealing effectiveness over time. BISCO® 7304's compression set of 20% at 22 hours, 212°F per ASTM D1056 — the lowest in the BISCO® flame resistant series — confirms superior dimensional recovery relative to competing grades, supporting long-term sealing integrity in demanding aerospace applications.
What is the temperature resistance range for BISCO® 7304?
The temperature resistance range is -67°F to 450°F as listed on the TDS.
Is BISCO® 7304 suitable for regulated aerospace and automotive environments?
Yes. BISCO® 7304 meets Boeing Material Specification BMS 1-23 for aerospace sealing applications, and passes FMVSS302 for automotive flame compliance, as listed on the TDS.
How should BISCO® 7304 be specified?
Specify grade (7304SIL), thickness (from the twelve available gauges), color (Red), applicable compliance requirements (FMVSS302, BMS 1-23), dimensional tolerances, and finished format (sheet, slit roll, or die-cut component).
