EPDM vs Silicone Sealing Strip: How to Choose the Right Material
Choosing between EPDM and silicone rubber is one of the first decisions in any sealing project. Both materials extrude well, both weather far better than natural rubber, and both can be supplied as solid, sponge or co-extruded profiles — but their cost, temperature window and chemical resistance differ enough to make the wrong choice expensive.
Quick comparison
| Property | EPDM | Silicone (VMQ) |
|---|---|---|
| Continuous temperature | -40 °C to +120 °C | -60 °C to +230 °C |
| Ozone / UV resistance | Excellent | Excellent |
| Tensile strength | High (mechanical robustness) | Moderate |
| Tear resistance | Good | Lower — needs design care |
| Water & steam | Very good | Good (steam grades available) |
| Oil & fuel | Poor | Poor to fair (FVMQ for fuel) |
| Food / medical grade | Possible but limited | Common (FDA, LFGB, USP Class VI) |
| Relative cost | Low | 2× – 4× higher |
When EPDM is the better choice
- Automotive body seals: door, hood, trunk and sunroof weatherstrips operate from -40 °C to +90 °C — well inside EPDM's window.
- Garage and industrial doors: abrasion and repeated compression are the main stresses, and EPDM offers higher mechanical strength.
- Cost-sensitive volume programmes: EPDM compound cost is a fraction of silicone, which matters on runs of tens of thousands of metres.
When silicone pays for itself
- High temperature: oven doors, engine bay charge-air connections, exhaust hangers and turbo hoses above 150 °C.
- Food, beverage and medical: FDA and LFGB compliant grades are standard, not special.
- Extreme cold flexibility: silicone stays soft down to -60 °C where EPDM starts to stiffen.
- Colour and translucency: silicone accepts bright, stable colours and clear finishes.
What we recommend
If the part lives below 120 °C, sees sunlight, water and mechanical wear, and the volume is high, start with EPDM. If it sees heat above 150 °C, food contact, or must stay flexible in deep cold, specify silicone. When in doubt, send us the application temperature, media and expected service life — we will compound and test a sample before quoting tooling.
FAQ
Can EPDM and silicone be co-extruded? Yes. A common construction is an EPDM body with a silicone bulb, or a solid carrier with a soft sponge bulb, giving both strength and sealing in one profile.
Is silicone always better? No. Silicone has lower tear strength and higher gas permeability, and it costs more. For a door seal that is squeezed thousands of times, EPDM usually lasts longer.
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