BISCO® MF1® Medium
BISCO® MF1® Medium is a medium-grade silicone foam cast into a block form with a density of 6.0 lb/ft³ and a compression force deflection range of 0.4–1.5 psi per ASTM D1056, designed for cushioning and sealing applications including passenger rail car and aircraft seating. The material is rated for recommended constant use to 392°F and passes FMVSS302 for flame resistance. It is FDA compliant in accordance with 21 CFR 177.2600.
Key Properties
- Compression Force Deflection: 0.4–1.5 psi (ASTM D1056)
- Tensile Strength: 12.5 psi (ASTM D412)
- Elongation: 45% (ASTM D412)
- Compression Set, 22 Hours @ 212°F @ 50%: 1.5% (ASTM D1056)
- Density: 6.0 lb/ft³ (ASTM D1056)
Recommended Constant Use: 392°F
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Thickness | Custom | — |
| Color | White | — |
| Material/Substrate | Silicone Foam | — |
| Density | 6.0 lb/ft³ | ASTM D1056 |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection | 0.4–1.5 psi | ASTM D1056 |
| Compression Set, 22 Hours @ 212°F @ 50% | 1.5% | ASTM D1056 |
| Tensile Strength | 12.5 psi | ASTM D412 |
| Elongation | 45% | ASTM D412 |
| Tear Strength | >2.0 ppi | ASTM D624 |
| Low Temperature Flex | Pass | ASTM D1056 |
Thermal Properties
| Property | Value | Test Method |
| Recommended Constant Use | 392°F | — |
| Thermal Conductivity (Uncompressed) | 0.037 W/mK | ASTM C518 |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Breakdown, Method C: Slow Rate of Rise (500 v/s) | 45 | ASTM D149 |
| Volume Resistivity | 7.0 × 10¹³ | ASTM D257 |
Flame & Fire Performance
| Property | Value | Test Method |
| FMVSS302 | Pass | — |
Environmental Performance
| Property | Value | Test Method |
| Ozone | Pass | — |
| UV Resistant | Pass | — |
Compliance
- FDA 21 CFR 177.2600 — Compliant
- FMVSS302 — Compliant (Pass)
- Seat cushions for passenger rail cars and aircraft requiring FST-compliant silicone foam with balanced compliance and durability
- Industrial gaskets and sealing components in thermally and chemically demanding environments
- Medical cushioning and impact protection components where FDA 21 CFR 177.2600 biocompatibility is required
- Custom die-cut sealing and cushioning solutions across industrial and transit applications
- Aerospace interior components and assemblies requiring FST compliance and mid-range compression response
Common industries: Mass transit, aerospace and defense, medical devices, industrial manufacturing, electronics.
BISCO® MF1® Medium is the mid-density grade in the MF1® bun silicone foam series at 6.0 lb/ft³, cast into block form and available in custom thicknesses.
It is designed for cushioning and sealing applications requiring a balance of compliance and durability — notably passenger rail car and aircraft seating, industrial gaskets, medical cushioning and impact protection, custom die-cut solutions, and demanding aerospace components requiring FST compliance. The bun-cast construction allows conversion into custom thickness profiles for a broad range of finished part geometries.
The material achieves a compression set of only 1.5% at 22 hours, 212°F, 50% deflection. Elongation of 45% — higher than the Firm grade’s 35% — provides greater conformance under load. Tear strength exceeds 2.0 ppi per ASTM D624. Low temperature flex passes per ASTM D1056. Thermal conductivity (uncompressed) is 0.037 W/mK per ASTM C518. Ozone and UV resistance both pass.
Dielectric breakdown (Method C, slow rate of rise, 500 v/s) is 45 per ASTM D149, and volume resistivity is 7.0 × 10¹³ per ASTM D257. FMVSS302 is passed for automotive and transit flame compliance.
Compliant with FDA 21 CFR 177.2600 and FMVSS302.
What differentiates MF1® Medium from the Firm and Soft grades in the MF1® series?
MF1® Medium is the mid-density grade in the MF1® bun silicone foam series at 6.0 lb/ft³, with a compression force deflection range of 0.4–1.5 psi — softer than the Firm grade (7.0 lb/ft³, 0.6–1.8 psi CFD) and firmer than the Soft grade (5.0 lb/ft³, 0.2–1.2 psi CFD). Its elongation of 45% is higher than the Firm grade's 35%, providing greater material conformance. It is appropriate for applications requiring a balance between cushion compliance and structural durability that neither the Firm nor Soft grade alone provides.
Why is compression set critical for a bun silicone foam used in seating and sealing?
Compression set measures the permanent deformation retained after a material has been held under compression at elevated temperature. For seat cushions, a high compression set means the foam does not return to its original thickness after extended use, resulting in degraded comfort and support. For seals and gaskets, permanent set means the material no longer fills the joint gap, permitting ingress of fluid, gas, or debris. MF1® Medium's compression set of 1.5% at 22 hours, 212°F, 50% deflection confirms near-complete dimensional recovery after sustained compression at elevated temperature — a fundamental indicator of long service life in both cushioning and sealing end uses.
What is the recommended constant use temperature for MF1® Medium?
The recommended constant use temperature is 392°F as listed on the TDS.
Is MF1® Medium suitable for regulated environments?
Yes. MF1® Medium is FDA compliant in accordance with 21 CFR 177.2600, supporting food-contact-adjacent and medical applications. It also passes FMVSS302 for automotive and transit flame compliance, and FST resistance performance is described as superior on the TDS, supporting mass transit and aerospace interior applications.
How should MF1® Medium be specified?
Specify grade (MF1MEDSIL), density (6.0 lb/ft³), CFD range (0.4–1.5 psi), color (White), applicable compliance requirements (FDA 21 CFR 177.2600, FMVSS302), custom thickness, dimensional tolerances, and finished format (bun block, sheet, or die-cut component).
