Silicone vs rubber: a buyer's comparison
Both families are called "rubber", but silicone and organic rubber (EPDM, NBR, NR, FKM) behave differently under heat, cold, oil and pressure. This page lays the trade-offs out side by side so you can pick the material that matches the working conditions, not the one that matches the catalogue.
When silicone wins
Temperature. Silicone spans −60 °C to +230 °C continuously; specialty compounds reach 300 °C. Organic rubber tops out around 120–150 °C before the material hardens and cracks.
Ageing. Silicone is UV-stable and ozone-stable. It does not bloom, does not plasticise over time and keeps its durometer for decades in storage.
Food and medical contact. Platinum-cured silicone is the default material for FDA 21 CFR 177.2600, LFGB §31 and EU 1935/2004 food-contact parts, and for USP Class VI and ISO 10993 medical parts. Organic rubber requires compounding tricks and rarely meets the same migration limits.
Compression set. Silicone recovers shape well at low strain. If the part is a static gasket under constant squeeze, silicone holds its sealing force longer.
When organic rubber wins
Tear and abrasion. Natural rubber and NBR tear at much higher force per mm than silicone of the same Shore A. If the part is a dynamic wiper or a moving boot, organic rubber survives longer.
Oil and fuel resistance. NBR and FKM (Viton) hold up against petroleum, diesel and hot oil; silicone swells in non-polar solvents. For an engine bay or a fuel-system gasket, FKM or HNBR is the right answer.
Unit cost. Organic rubber compounds cost a fraction of silicone per kg. For high-volume commodity seals — washing machine door gaskets, drainage O-rings — the unit-cost gap is decisive.
High-pressure dynamic seals. Hydraulic O-rings under continuous 20–40 MPa load still default to NBR or FKM because silicone extrudes under sustained pressure.
Comparison table
| Property | Silicone (LSR / HCR) | NBR | EPDM | FKM (Viton) | Natural rubber |
|---|---|---|---|---|---|
| Temperature range (continuous) | −60 °C to +230 °C | −30 °C to +110 °C | −50 °C to +150 °C | −20 °C to +200 °C | −50 °C to +80 °C |
| Hardness range (Shore A) | 10–80 | 30–90 | 40–80 | 60–90 | 30–90 |
| Tear strength | Low–Medium | Medium | Medium | Medium–High | High |
| Compression set (24h @ 100 °C) | 10–25 % | 15–30 % | 15–30 % | 10–20 % | 20–35 % |
| Oil resistance | Poor | Excellent | Poor | Excellent | Poor |
| Food contact (FDA / LFGB) | Yes (platinum cure) | Limited | Limited | Limited | No |
| Tooling cost (single-cavity) | Medium | Low | Low | Medium–High | Low |
| Unit cost at 1,000 pcs | Medium | Low | Low | High | Low |
What we mold
We run three silicone processes (LSR injection, HCR compression, peroxide-cured HTV) on three plants. We also mold NBR, HNBR and FKM on our Dongguan industrial line for engine, hydraulic and high-temperature sealing applications. Tell us the working conditions and we will propose the material; you do not need to settle that question before you send the drawing.
FAQ — silicone vs rubber
Is silicone rubber more expensive than organic rubber?
Per kilogram, silicone compound costs more than natural rubber or NBR. Per finished part, the gap narrows because silicone parts are often thinner and lighter, and the longer service life shifts the cost calculus. For a static food-contact gasket, the lifetime cost of silicone is usually lower than NBR.
Can silicone replace NBR in an oil-resistant application?
No. NBR is specified for petroleum oils because silicone swells in non-polar solvents. If the part sees hot oil or fuel, stay with NBR or move up to FKM (Viton).
Is silicone food-safe by default?
No. Only platinum-cured silicone that meets FDA 21 CFR 177.2600, LFGB §31 and EU 1935/2004 is food-safe. Peroxide-cured silicone and HTV can leave extractables. Always ask for the compliance certificate before specifying a food-contact part.
Which material handles 200 °C continuous?
Silicone is the default. FKM handles up to 200 °C in some grades. EPDM is rated to 150 °C continuous. NBR and natural rubber are not suitable above 110–120 °C.