Gaskets vs Seals: What’s The Difference and Why Does It Matter?
Are gaskets and seals the same thing?
Yes and no. While the terms gasket and seal are often used interchangeably, they refer to distinct components with different functions — especially in engineering and manufacturing applications.
A gasket typically seals against dust, moisture, chemicals, and other contaminants by forming a tight barrier between two static surfaces. In contrast, a seal usually refers to a component used in dynamic applications, such as shafts or pumps, where movement is involved.
Let’s take a closer look at the key differences between gaskets and seals — and how choosing the right one impacts performance and longevity.
Gaskets vs. Seals: Key Differences
What Is a Gasket?
Gaskets are used in static applications where two stationary components, such as flanges or housing joints, need to be joined. The gasket fills the microscopic gaps between the surfaces, forming a seal through compression.
Key characteristics:
- Used in static joints (e.g., flanges, covers, enclosures)
- Compresses to form a seal and prevent leaks or contamination
- Often die-cut to custom shapes
- Requires no machining of mating surfaces
- Applied using adhesives or mechanical fasteners
Common foam gasket materials:
What Is a Seal?
Seals are designed for dynamic applications, where parts are in motion relative to one another — such as rotating shafts or reciprocating pistons. They prevent leakage of fluids (like oil or grease) and keep out contaminants like dust, dirt, and water.
Key characteristics:
- Used in dynamic environments (e.g., motors, pumps, gearboxes)
- Prevents leakage around moving parts
- Often includes a rubber sealing lip and a metal casing for stability
- Engineered to withstand friction, heat, and fluid exposure
Anatomy of a Gasket: A Three-Part Assembly and Sealing System
A typical gasket assembly includes:
- Mating Surfaces (flanges or joints): The flat surfaces that compress the gasket.
- Gasket: A flexible, elastomeric component die-cut to fit the joint.
- Fasteners: Adhesives or mechanical pressure maintain gasket compression and sealing integrity.
Compression is the primary method by which gaskets seal. However, selecting the right material is just as important to ensure long-term performance in your specific environment.
How to Choose the Right Foam Gasket Material
These are some of the key factors when choosing the best gasket material for your application.
Compression Set Resistance
If a gasket will be opened and reclosed frequently, choose materials with low compression set (they spring back to their original shape). High compression set materials, while not reusable, can be cost-effective for permanent seals.
Durometer (Hardness)
Durometer measures how soft or hard a material is. A gasket must be soft enough to form a seal under pressure, yet firm enough to resist extruding under load.
Environmental Resistance
To avoid degraded performance over time, consider the environment and how the material works against various elements, including dust, high temperatures, UV rays, chemicals and solvents. Your material should be chemically and thermally stable under these conditions.
Compliance and Standards
SRP can help ensure your material meets all required specifications. Depending on your industry, your gasket material may need to meet certifications for:
- Flame resistance
- Low VOC off-gassing
- FDA compliance
- High operating temperatures
What Is a Rubber Seal?
Unlike gaskets, rubber seals are used primarily to prevent fluid leaks in systems with motion. A classic example is the O-ring, which sits in a groove and compresses to block fluid flow.
Common uses:
- End of rotating shafts
- Hydraulic or pneumatic systems
- Engine components
- Bearing protection
Rubber seals are engineered to endure dynamic forces, including axial and radial motion, pressure changes, and temperature variation.
Common types of rubber seals:
- O-rings
- Rotary shaft seals
- Valve stem seals
- Mechanical face seals
Why It Matters
Choosing the wrong component — or material — can lead to premature failure, increased maintenance, and costly downtime. Knowing the difference between a gasket and a seal ensures proper function, longer service life, and better performance for your equipment.
Work With a Trusted Custom Gasket Manufacturer
At SRP, we bring more than 70 years of experience in custom die-cutting and material converting. Whether you need foam gaskets for enclosures or dynamic sealing components for demanding applications, we help OEMs achieve reliable sealing performance at the right price.
Ready to get started? Send us your specs, and we’ll deliver a fast, accurate quote.