Silicone rubber is one of the most versatile elastomers1, used in industries ranging from medical devices to automotive components. However, not all silicone rubber is the same—different grades are formulated to meet specific performance, safety, and regulatory requirements.
Silicone rubber is categorized into different grades based on purity, performance, and application, including general-purpose, food-grade, medical-grade, high-temperature, and electrically conductive silicone.
In this guide, we’ll explore the different grades of silicone rubber, their properties, and their applications.
1. General-Purpose Silicone Rubber
General-purpose silicone rubber is the most cost-effective and widely used grade, designed for basic sealing, insulation, and mechanical applications.
Key Features:
- ✅ Good flexibility and weather resistance.
- ✅ Temperature range: -50°C to +200°C.
- ✅ Moderate chemical resistance.
Common Applications:
| Industry | Application |
|---|---|
| Automotive | Engine gaskets, hoses, weather seals |
| Industrial | Machinery seals, O-rings, tubing |
| Consumer | Keypads, household products |
General-purpose silicone lacks certifications for food or medical contact but is widely used in industrial applications.
2. Food-Grade Silicone Rubber (FDA-Approved)2
Food-grade silicone is formulated to meet FDA (CFR 21 177.2600) and EU food safety regulations, making it safe for direct food contact.
Key Features:
- ✅ Non-toxic, BPA-free, and odorless.
- ✅ Resists heat and cold (-50°C to +230°C).
- ✅ Does not react with food or beverages.
Common Applications:
| Product Type | Application |
|---|---|
| Kitchenware | Baking mats, spatulas, oven mitts |
| Baby Products | Pacifiers, bottle nipples, teething rings |
| Food Processing | Gaskets, tubing, seals for food manufacturing |
Food-grade silicone rubber is ideal for cookware and food-handling applications due to its safety and durability.
3. Medical-Grade Silicone Rubber (ISO 10993 & USP Class VI)3
Medical-grade silicone is designed for biocompatibility and safe human contact, making it suitable for healthcare and pharmaceutical applications.
Key Features:
- ✅ Meets USP Class VI & ISO 10993 biocompatibility standards.
- ✅ Hypoallergenic and sterilizable (autoclave, gamma radiation).
- ✅ Can be used for implants and surgical devices.
Common Applications:
| Industry | Application |
|---|---|
| Medical Devices | Catheters, surgical tubing, implants |
| Pharmaceutical | Drug delivery systems, syringe seals |
| Healthcare | Wound dressings, respiratory masks |
Medical-grade silicone undergoes rigorous safety testing, making it more expensive but essential for healthcare use.
4. High-Temperature Silicone Rubber (HTV & LSR)4
High-temperature silicone rubber is engineered to withstand continuous exposure to extreme heat without degrading.
Key Features:
- ✅ Can tolerate up to +300°C (higher than standard silicone).
- ✅ Excellent resistance to oxidation and thermal aging.
- ✅ Maintains flexibility at low temperatures.
Common Applications:
| Industry | Application |
|---|---|
| Aerospace | Jet engine seals, high-temp gaskets |
| Automotive | Turbocharger hoses, exhaust seals |
| Electronics | Heat-resistant wire insulation |
High-temperature silicone rubber is essential for applications requiring extreme heat resistance.
5. Electrically Conductive Silicone Rubber
Electrically conductive silicone combines flexibility with conductivity, making it ideal for shielding, sensors, and EMI protection.
Key Features:
- ✅ Conducts electricity while maintaining flexibility.
- ✅ Used for EMI shielding and static dissipation.
- ✅ Can be molded into custom electrical components.
Common Applications:
| Industry | Application |
|---|---|
| Electronics | EMI shielding gaskets, keypads |
| Medical | Sensors, wearable devices |
| Defense | Communication systems, aerospace |
Conductive silicone rubber is used in advanced technology applications where standard rubber insulation is not enough.
6. Fluorosilicone Rubber (FVMQ)
Fluorosilicone rubber is a specialized elastomer with superior resistance to fuels, oils, and solvents, making it ideal for harsh chemical environments.
Key Features:
- ✅ Highly resistant to fuels, oils, and solvents.
- ✅ Performs well in extreme temperatures (-60°C to +230°C).
- ✅ More chemically resistant than standard silicone.
Common Applications:
| Industry | Application |
|---|---|
| Automotive | Fuel system seals, gaskets |
| Aerospace | Jet fuel-resistant O-rings, gaskets |
| Chemical Processing | Seals for corrosive environments |
Fluorosilicone is more expensive but necessary for applications exposed to aggressive chemicals.
7. Sponge Silicone Rubber (Foamed & Closed-Cell)
Sponge silicone is a lightweight, flexible, and compressible material used for gaskets, insulation, and cushioning.
Key Features:
- ✅ Closed-cell structure prevents water absorption.
- ✅ Highly compressible with excellent rebound.
- ✅ Maintains flexibility in extreme temperatures.
Common Applications:
| Industry | Application |
|---|---|
| HVAC | Sealing and insulation in ductwork |
| Automotive | Vibration dampening pads |
| Medical | Soft gaskets, surgical padding |
Sponge silicone is ideal for soft, lightweight sealing applications.
Comparison of Silicone Rubber Grades
| Grade | Key Features | Common Applications |
|---|---|---|
| General-Purpose | Basic flexibility, moderate durability | Automotive seals, O-rings |
| Food-Grade (FDA) | Safe for food contact, heat-resistant | Kitchenware, baby products |
| Medical-Grade | Biocompatible, sterilizable, hypoallergenic | Implants, medical tubing |
| High-Temperature | Withstands up to 300°C, heat-resistant | Aerospace, automotive gaskets |
| Electrically Conductive | Conductive, EMI shielding, flexible | Electronics, sensors, defense |
| Fluorosilicone | Resistant to fuels, oils, solvents | Aerospace, automotive fuel systems |
| Sponge Silicone | Lightweight, compressible, insulating | Gaskets, HVAC, vibration damping |
Conclusion
Choosing the right grade of silicone rubber depends on your specific application requirements. If you need food safety, opt for FDA-approved silicone. If you're working with medical devices, use medical-grade silicone. For high-temperature applications, HTV silicone is the best choice.
By understanding these silicone rubber grades, you can select the ideal material for your industry needs.
Explore this link to understand the wide-ranging applications and benefits of versatile elastomers in various industries. ↩
Explore the benefits of FDA-approved silicone for safe food contact and its applications in kitchenware and baby products. ↩
Learn about the importance of medical-grade silicone in healthcare and its biocompatibility for safe human contact. ↩
Discover how high-temperature silicone rubber withstands extreme heat and its critical applications in aerospace and automotive industries. ↩
