Foam vs. Solid Rubber: What Makes a Better Gasket?

Foam and rubber are two of the most common materials used in gasketing applications, and for good reason. The nature of a gasket is to create a seal that prevents either gas, liquid, or both from getting through. Both foam and rubber lend themselves well to this task, but neither of them is the “better choice” across all gasketing applications. Each material has certain properties that make it the ideal choice based on certain conditions. The material your gasket application requires is dependent on your specific application case, and we can help you make that choice based on your project. 

Do you need foam or solid rubber for your gasketing application? We're happy to help with that. First, we’ll cover the major differences between the two materials, the advantages of using them as a gasket material, and what you need to consider when making the right choice for your application. 

The Advantages of Foam Gaskets 

Foam lends itself to gasketing applications because its closed-cell variations have internal structures made of cells that are enclosed by their walls and tightly packed together. This creates a material that prevents the flow of air, vapor, and liquid penetration—exactly what you need in a gasket. There are a wide variety of closed cell foam options and densities, giving you options when it comes to compression deflection and compression set, environmental and chemical resistances, and other properties. While the materials and their properties vary, there are some common advantages to using them for your gasket. In general, gaskets made of foam materials are: 

  • More flexible and malleable: this provides the ability for the gasket to conform better to uneven surfaces or tolerance mismatches. 

  • Easier to create a positive seal: materials compressed greater 15% to 50% of their original thickness form excellent positive seals, which help r deter leakage.  

  • Able to cushion better than solid rubber: foam gaskets are much better for applications where the gasket needs to provide a cushion between the two parts being joined.  

  • Available in open cell varieties: you do have the option of using open cell foams, which are available in high density and low-density options. Low density open cell foams are ideal for filtration applications because they are a porous material that blocks out dust and debris while allowing gases and liquids to pass through. High density open cell foams act as excellent isolators, maintaining good stress relaxation and a low compression set. 

  • Able to cushion better than solid rubber: foam gaskets are much better for applications where the gasket needs to provide a cushion between the two parts being joined. 

  • Commonly blended: some closed cell foam materials can be blended to create custom materials for highly specific applications that deliver some of the best properties of each material depending on your needs.  For example, vinyl nitrile foam combines the soft flexibility of PVC foam with the oil and solvent resistance of Nitrile. 

The Advantages of Solid Rubber Gaskets 

Rubber gaskets are made from materials that are durable and highly reliable when used within their specifications. They can be used across a variety of applications because of their many benefits, and they are very common in areas that involve food, electricity, and high temperatures. There are many types of rubber that can be fabricated into custom gaskets, and the many benefits they provide include: 

  • A higher durability and resilience: rubber is a tough material that has a high shock absorption as well as impact and abrasion resistance. 

  • High temperature resistance: Generally solid rubber can withstand higher temperatures than their foam counterparts.  Some rubber materials can withstand temperatures as high as 250°F. Silicone rubber can withstand temperatures as high as 500°F. This makes them ideal for use in HVAC, automotive, industrial, aerospace, and marine applications. 

  • Dimensional stability and high tensile strength: it’s difficult to compress rubber materials to the point of deformation. The materials also have high tensile strength, meaning they are hard to break when stretched. 

  • Resistance to abrasion and wear: most rubber materials will not easily break down over time. They also can’t easily be scratched when used in conjunction with a rough surface. You’ll find that rubber is generally much more durable than foam. 

  • Being suitable for food applications: because (food safe) rubber materials are non-toxic, non-allergenic, resistant to mold growth, do not emit odors, and able to withstand high temperatures, they are some of the only gasket materials that can be used in applications in direct contact food preparation and packaging industries. 

Rubber Gasket Product Options 

  • Solid Neoprene (CR) Rubber: this general-purpose rubber is fabric reinforced, allowing it to be used as a gasket that also isolates noise and provides some vibration attenuation. It’s also highly flexible and flame resistant, making it ideal for military applications. 

  • Solid Ethylene Propylene Diene Monomer (EPDM) Rubber: EPDM has a high resistance to ozone, UV light, and other outdoor elements, making it ideal for weather stripping and as window spacers. The material is also an excellent electrical insulator with a wide operating temperature range. Military versions are available. 

  • Solid Nitrile (NBR) Rubber: NBR is most known for its resistance to oil and petroleum as well as other hydraulic fluids. This makes it ideal for sealing in appliances. There are also food grade versions that meet FDA standards. 

  • Solid Natural (NR) Rubber: because of its excellent flexibility and vibration/shock absorption, natural rubber makes an ideal for linings, shock mounts, bumpers, etc. 

  • Solid Styrene-Butadiene (SBR) Rubber: this basic gasket material is used in a variety of applications. It’s non hardening and quick sealing, on top of having a high electrical resistance. 

  • Solid Silicone Rubber: silicone rubber is one of the most durable materials with the widest range of operating temperatures and resistances. It will last in nearly any condition and is also easy to sterilize to make it food safe.  

Finding the Right Gasket for Your Application 

At Engineered Materials, we work many foam and solid rubber materials, each of which is available in a wide range of thicknesses and can be combined with your choice of pressure sensitive adhesive tape. Our material selection is vast and our custom fabrication capabilities allow us to provide your gasket parts in slit rolls, die-cut parts, or three-dimensional shapes, all to your specifications. 

It all begins with selecting the right material for your gasket, which depends on: 

  • What you’re sealing against 

  • The operating temperature 

  • Potential environmental exposures (UV, ozone, etc.) 

  • The expected pressure and needed compression set 

  • The needed durometer (hardness) of your material 

  • Any chemical exposure 

  • EMI/RFI shielding capabilities 

To learn more about how to choose the right material for your application, read this guide or get in touch with us today to talk about the needs of your application. 

Matt Tempelis