Choosing between two rubber compounds can be difficult when both appear to meet the basic requirements of a part. With EPDM and silicone, the differences become clearer once the application and operating environment come into focus. EPDM and silicone are chemically different elastomers, and that difference affects how they respond to heat, outdoor exposure, moisture, and other conditions. At Reiss Manufacturing, we believe material selection should start with those performance requirements, followed by the manufacturing process and specifications for the finished component.
Neither material is the right answer for every application. Silicone is often selected when temperature performance and flexibility across changing conditions are priorities. EPDM is commonly considered for applications involving outdoor exposure, water, and weathering. Understanding where each material performs well makes it easier to determine which compound fits the job.
What Is Silicone Rubber?
Silicone rubber is an elastomer made from a polymer with a silicon-oxygen backbone. This structure is different from the carbon-based backbone found in many organic rubbers, including EPDM, and contributes to several of the characteristics associated with silicone.
One of silicone’s most useful qualities is its ability to maintain its properties across demanding temperature conditions. It is also known for flexibility, resistance to ozone and weathering, and electrical insulating properties. Depending on the formulation, silicone can be manufactured to meet the needs of applications across a variety of industries.
At Reiss, silicone is central to much of what we manufacture. We work with silicone through molding, extrusion, calendering, and secondary fabrication to produce components ranging from molded parts and extruded profiles to tubing and sheeting.
What Is EPDM Rubber?
EPDM stands for ethylene propylene diene monomer. It is a synthetic rubber made from ethylene, propylene, and a diene component. Its chemical structure gives EPDM a different set of performance characteristics from silicone.
EPDM is well known for its resistance to weathering, ozone, water, and outdoor exposure. These characteristics make it useful for components that need to withstand environmental conditions over time. EPDM is also used where resistance to certain chemicals, including many dilute acids and alkalis, is required.
Like silicone, however, EPDM should not be chosen based on one property alone. The specific compound, operating environment, part design, and manufacturing requirements all matter. Compatibility with oils, fuels, chemicals, and other substances the component may encounter should be evaluated for the application rather than assumed from the material name alone.
EPDM vs Silicone: What Are the Key Differences?
The most useful way to compare EPDM vs silicone is to look at the conditions the finished part will actually encounter. Both materials offer weathering resistance and can be used in demanding environments, but their strengths are not identical.
Heat and Temperature Performance
Temperature is one of the clearest areas of distinction between the two materials. Silicone is particularly well suited to applications where heat resistance is a primary concern. Its ability to retain useful properties under high-temperature conditions is one reason silicone is used for seals and other components that may be exposed to elevated heat.
EPDM also performs across a range of operating conditions, but silicone is generally the stronger candidate when sustained or more demanding high-temperature exposure is part of the application.
Different formulations can behave differently, so a material should not be approved for an application based solely on a general temperature characteristic.
Weather, Ozone, and Outdoor Exposure
EPDM is widely used for applications exposed to weather, ozone, and outdoor conditions. That makes it a strong option for components that spend much of their service life outdoors or regularly encounter the elements.
Silicone also offers strong resistance to weathering and ozone, so outdoor exposure does not automatically mean EPDM is the better choice. Other requirements may shift the decision toward silicone, particularly when the same component must also perform under demanding temperature conditions.
For engineers and buyers, this is a good example of why material selection rarely comes down to a single checkbox. If both materials address one environmental requirement, the remaining operating conditions can help determine which one is the better fit.
Water and Moisture Exposure
EPDM is known for its resistance to water and is commonly considered for components that encounter wet environments. Its resistance to water, weathering, and ozone can make that combination particularly useful for outdoor sealing applications.
Silicone also has applications where moisture is present. The choice between the two depends on what else the component will encounter, including temperature, environmental exposure, and any chemicals or fluids involved. If water exposure is only one part of the operating environment, looking at the complete set of requirements helps avoid choosing a compound that solves one problem while creating another.
Chemical and Fluid Compatibility
Chemical compatibility is another area where the details matter. EPDM can resist a range of substances, including many dilute acids and alkalis, but it is generally not selected for applications involving petroleum-based oils and fuels. Silicone has its own compatibility considerations and should not be assumed to resist every oil, fuel, solvent, or chemical simply because it performs well in other demanding environments.
For either material, the specific fluid or chemical should be identified before the compound is selected. Concentration, exposure conditions, and the formulation of the rubber can all affect suitability.
Flexibility and Physical Performance
Silicone is valued for remaining flexible across changing temperature conditions. That can be useful for seals, gaskets, tubing, and other parts that need to maintain their function as the surrounding environment changes.
EPDM also provides the elastic behavior expected from a rubber material and can perform well in sealing and molded-part applications. The right choice depends on what the component needs to do rather than which material has the longer list of general advantages. Part geometry matters here as well. A molded component, thin sheet, tube, gasket, or extruded profile can place different demands on the material. The manufacturing method therefore needs to be considered alongside physical performance.
When Is Silicone the Better Choice?
Silicone is often the better candidate when the application places a strong emphasis on temperature performance, flexibility, or a combination of environmental demands.
For example, a component may need to remain flexible while being exposed to changing temperatures. Another part may require the advantages of silicone along with a manufacturing process such as extrusion or calendering. In those cases, both material performance and the way the part will be made point toward silicone.
Silicone is also used across industries with very different requirements. At Reiss, the markets we serve include aerospace, automotive and transportation, construction, electrical, industrial, medical and pharmaceutical, consumer products, and other specialized applications.
The important point is that silicone should be selected because its properties fit the component’s requirements, not simply because it is a versatile material.
When Is EPDM the Better Choice?
EPDM can be a strong candidate when outdoor exposure, ozone, weathering, or water resistance are major requirements and the rest of the operating environment is compatible with the material.
That combination makes EPDM worth considering for molded seals, gaskets, and other components exposed to environmental conditions. If high-temperature performance is the overriding concern, silicone may offer a better fit. If outdoor weathering and water exposure are central to the application, EPDM may deserve closer consideration.
Fluid exposure can also influence the decision. Because EPDM is not generally the material of choice for petroleum-based oils and fuels, the complete operating environment should be reviewed before specifying it.
How to Choose Between EPDM and Silicone
The EPDM vs silicone decision is best made from the application backward. Start with what the component will encounter and what it needs to accomplish, then determine which material and compound align with those requirements.
A drawing may specify dimensions and geometry in detail without telling the full story of how a rubber part will be used. Before settling on a material, it helps to answer a few practical questions:
- Will the component encounter elevated heat or significant temperature changes?
- Will it be installed outdoors or exposed to weather and ozone?
- Will it regularly come into contact with water or moisture?
- Will oils, fuels, chemicals, or other fluids contact the part?
- Does the component need to remain flexible under changing operating conditions?
- Is the part molded, extruded, calendered, or fabricated?
- What quality and performance requirements apply to the finished component?
These questions help narrow the decision because they focus on the conditions that distinguish one material from another.
The compound itself also matters. “Silicone” and “EPDM” describe broad material families, and individual formulations can be developed for different requirements. Customers should evaluate the specified compound in the context of the actual application rather than relying solely on the general characteristics of either material.
Silicone and EPDM Capabilities at Reiss Manufacturing
Once the optimal material has been selected, the next question is how the component will be manufactured. At Reiss Manufacturing, we work with customers across a wide range of industries to manufacture rubber components to their specifications. Our silicone capabilities include molding, extrusion, calendering, and secondary fabrication. These processes allow us to manufacture silicone products in a variety of forms, including molded components, extruded products, tubing, and sheeting.
We also have significant experience molding EPDM; however our current equipment stack does not allow for EPDM extrusion. Customers sourcing molded components can choose between silicone and EPDM for their application. Our approach starts with understanding the customer’s specifications and what the finished component needs to accomplish. Material, geometry, manufacturing method, and quality requirements all need to work together to produce the intended result.
Work With Reiss Manufacturing on Your Next Rubber Component
Choosing between EPDM and silicone is easier when the decision starts with the actual demands placed on the part. At Reiss Manufacturing, we bring our rubber manufacturing experience to that conversation and work from the customer’s specifications to manufacture components for demanding B2B applications.
If you have a drawing, specification, or rubber component ready for production, contact Reiss Manufacturing to request a quote. Our team can review your project and determine how our manufacturing capabilities align with your requirements.
EPDM vs Silicone FAQs
EPDM and silicone are different types of synthetic elastomers with different chemical structures and performance characteristics. Silicone stands out for its temperature performance and flexibility across changing conditions, while EPDM is particularly well known for weathering, ozone, and water resistance.
Silicone is generally the stronger choice when high-temperature performance is a major requirement. The specific compound and operating conditions should still be evaluated before a material is selected.
EPDM is well known for resistance to weathering and ozone, making it a strong candidate for many outdoor applications. Silicone also resists weathering, so other requirements should be considered before making a final selection.
Water resistance is one of the characteristics associated with EPDM, which is why it is considered for many wet and outdoor environments. The complete application should still be evaluated before specifying a compound.
EPDM is generally not selected for applications involving petroleum-based oils and fuels. Fluid compatibility should always be checked against the specific compound and conditions of the application.
Yes. Silicone offers resistance to weathering and ozone, which allows it to be considered for outdoor applications as well as applications with other demanding environmental requirements.
Start with the operating environment and performance requirements. Temperature, weather exposure, water, chemicals and fluids, flexibility, part design, and manufacturing method can all help determine which material is better suited to the component.
Yes. We have molding capabilities for both silicone and EPDM and can review molded-component requirements against our manufacturing capabilities.
Extrusion is one of our primary silicone manufacturing capabilities, along with molding, calendering, and secondary fabrication.
