kSil® GP40
kSil® GP40 is a general purpose solid silicone elastomer rated at 40 Shore A, providing a balance of flexibility and strength with the highest tear strength in the GP series at 23 N/mm (~131 ppi). It delivers 9 MPa (~1305 psi) tensile strength and 525% elongation, with compression set of 22% (22 hours @ 300°F) and 25% (24 hours @ 150°C). The material meets multiple international compliance standards including FDA 21 CFR 177.2600, FAR 25.853, FMVSS 302, and WRAS.
Key Properties
- Durometer: 40 Shore A — ISO 48-4
- Tensile Strength: 9 MPa (~1305 psi) — ISO 37 Type 2
- Elongation: 525 % — ISO 37 Type 2
- Compression Set, 22 Hours @ 300°F: 22 % — ISO 815, 22h @175°C
- Thermal Conductivity: 0.24 W/m·°C — ASTM C518
Tear Strength: 23 N/mm (~131 ppi) — ASTM D624 Die B
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 | Unit | Test Method |
| Colors Available | Translucent, Red Iron Oxide (RIO), Black, White, Blue | Visual | Visual |
Mechanical Properties
| Property | Value | Unit | Test Method |
| Durometer | 40 | Shore A | ISO 48-4 |
| Tensile Strength | 9 MPa (~1305 psi) | MPa | ISO 37 Type 2 |
| Elongation | 525 | % | ISO 37 Type 2 |
| Compression Set — 22 Hours @ 300°F | 22 | % | ISO 815, 22h @175°C |
| Compression Set — 24 Hours @ 150°C | 25 | % | ISO 815, 24h @150°C |
| Tear Strength | 23 N/mm (~131 ppi) | N/mm | ASTM D624 Die B |
Thermal Properties
| Property | Value | Unit | Test Method |
| Thermal Conductivity | 0.24 | W/m·°C | ASTM C518 |
Regulatory / Compliance Data
| Property | Value | Test Method |
| FDA 21 CFR 177.2600 | Compliant | — |
| FAR 25.853 | Compliant | — |
| FMVSS 302 | Compliant | — |
| WRAS | Compliant | — |
Compliance
- FDA 21 CFR 177.2600 — Compliant
- FAR 25.853 — Compliant
- FMVSS 302 — Compliant
- WRAS — Compliant
- Gaskets and seals requiring the highest tear resistance in the GP series alongside medium-soft compliance
- Food contact components requiring FDA 21 CFR 177.2600 compliant silicone
- Aerospace sealing assemblies compliant with FAR 25.853
- Automotive sealing components compliant with FMVSS 302
- Water contact applications requiring WRAS-compliant silicone elastomer
Common industries: Food processing, aerospace, automotive, water infrastructure, general industrial.
kSil® GP40 is a medium-soft grade in the kSil® GP general purpose solid silicone series at 40 Shore A, offering a balance of flexibility and tensile strength for gaskets, seals, and food contact components in aerospace, automotive, food processing, and water contact environments.
It delivers 9 MPa (~1305 psi) tensile strength and 525% elongation — and the highest tear strength in the GP series at 23 N/mm (~131 ppi) — making it particularly well suited for applications where resistance to tearing during installation or in-service loading is a priority alongside medium-soft compliance.
Colors are available as Translucent, Red Iron Oxide (RIO), Black, White, and Blue. Shelf life is defined as the duration of time for which the product will meet the physical characteristics outlined on the TDS; it does not guarantee the product’s usefulness in all applications.
Compliant with FDA 21 CFR 177.2600, FAR 25.853, FMVSS 302, and WRAS.
What differentiates kSil® GP40 from other grades in the GP series?
kSil® GP40 delivers the highest tear strength in the kSil® GP series at 23 N/mm (~131 ppi) while maintaining a medium-soft 40 Shore A durometer and 525% elongation. It is the appropriate selection when gaskets or seals must resist tearing during installation or service without sacrificing the flexibility and conformability needed for medium-soft sealing applications.
Why is compression set an important consideration for solid silicone elastomers?
Compression set measures how well an elastomer recovers its original thickness after sustained compression. In sealing applications, a material with high compression set will permanently deform over time, reducing sealing force and allowing leak paths to develop. kSil® GP40 achieves 22% compression set (22 hours @ 300°F per ISO 815) and 25% (24 hours @ 150°C), supporting sustained sealing performance across its service temperature range.
What is the operating temperature range for kSil® GP40?
No operating temperature range is specified on the manufacturer's TDS for this material. Compression set conditions tested at 300°F (175°C) and 150°C indicate suitability for elevated temperature service. Contact H-O Products Corporation for application-specific temperature guidance.
Is kSil® GP40 suitable for aerospace, automotive, food contact, and regulated environments?
Yes. kSil® GP40 meets FDA 21 CFR 177.2600, FAR 25.853 (aerospace), FMVSS 302 (automotive), and WRAS (water contact), as stated on the TDS.
How should kSil® GP40 be specified?
Specify grade (kSil® GP40), thickness, color (Translucent, Red Iron Oxide, Black, White, or Blue), compliance requirements, dimensional tolerances, and finished format.
