BISCO® MF1® Firm
BISCO® MF1® Firm is a firm-grade silicone foam cast into a block form with a density of 7.0 lb/ft³ and a compression force deflection range of 0.6–1.8 psi per ASTM D1056, designed for cushioning and sealing applications including passenger rail car 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: 0.6–1.8 psi (ASTM D1056)
- Tensile Strength: 13.5 psi (ASTM D412)
- Elongation: 35% (ASTM D412)
- Compression Set, 22 Hours @ 212°F @ 50%: 1.5% (ASTM D1056)
- Density: 7.0 lb/ft³ (ASTM D1056)
- Recommended Constant Use: 392°F
We want to help!
Enter your information and we'll get you in touch with our knowledgable staff. We know how important to the right product for your project.
Request a Consultation
- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Thickness | Custom | — |
| Color | White | — |
| Material/Substrate | Silicone Foam | — |
| Density | 7.0 lb/ft³ | ASTM D1056 |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection | 0.6–1.8 psi | ASTM D1056 |
| Compression Set, 22 Hours @ 212°F @ 50% | 1.5% | ASTM D1056 |
| Tensile Strength | 13.5 psi | ASTM D412 |
| Elongation | 35% | 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) | 0.043 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 and interior components for passenger rail cars and aircraft requiring FST compliance
- Industrial gaskets and sealing components in environments with elevated temperature and UV exposure
- Medical cushioning and impact protection components where FDA 21 CFR 177.2600 biocompatibility is required
- Aerospace components and spacecraft thermal protection applications requiring firm, durable silicone foam
- Shock and vibration management within electronic devices and military equipment assemblies
Common industries: Mass transit, aerospace and defense, medical devices, industrial manufacturing, electronics.
BISCO® MF1® Firm is the highest-density grade in the MF1® bun silicone foam series at 7.0 lb/ft³, cast into block form and available in custom thicknesses.
It is designed for cushioning and sealing applications where firmness, durability, and fire, smoke, and toxicity (FST) compliance are primary requirements — notably passenger rail car and aircraft seating, industrial gaskets, medical cushioning, aerospace components, and vibration and shock absorption in electronic devices. 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, demonstrating strong resistance to permanent deformation under sustained load at elevated temperature. Tear strength exceeds 2.0 ppi per ASTM D624. Low temperature flex passes per ASTM D1056. Thermal conductivity (uncompressed) is 0.043 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, supporting use in electronics and electrical assemblies. FMVSS302 is passed for automotive and transit flame compliance.
Compliant with FDA 21 CFR 177.2600 and FMVSS302.
What differentiates MF1® Firm from the Medium and Soft grades in the MF1® series?
MF1® Firm is the highest-density grade in the MF1® bun silicone foam series at 7.0 lb/ft³, with a compression force deflection range of 0.6–1.8 psi and the highest tensile strength in the series at 13.5 psi. These values make it the appropriate choice where greater resistance to deflection under load is required, such as structural seat cushions and firm industrial gaskets, compared to the Medium (6.0 lb/ft³, 0.4–1.5 psi CFD) and Soft (5.0 lb/ft³, 0.2–1.2 psi CFD) grades.
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 loss of comfort and support over the product's service life. For seals and gaskets, permanent set means the material no longer fills the joint gap, allowing fluid, gas, or debris ingress. MF1® Firm's compression set of 1.5% at 22 hours, 212°F, 50% deflection confirms that the material returns to near-original geometry after sustained compression at elevated temperature — a critical performance indicator for both cushioning and sealing life.
What is the recommended constant use temperature for MF1® Firm?
The recommended constant use temperature is 392°F as listed on the TDS.
Is MF1® Firm suitable for regulated environments?
Yes. MF1® Firm 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. FST (flame, smoke, and toxicity) resistance performance is described as superior on the TDS, supporting mass transit and aerospace interior applications.
How should MF1® Firm be specified?
Specify grade (MF1FIRMSIL), density (7.0 lb/ft³), CFD range (0.6–1.8 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).
