Foam Compression

Foam compression is what happens when pressure is applied to foam, squeezing its cells and temporarily reducing its volume. How a foam responds to compression, and how well it recovers, is central to its performance in applications from cushioning in furniture to insulation in construction, so it matters to anyone involved in producing, choosing or using foam products.

Foam is a cellular structure made of gas trapped in a solid. Its light weight, insulating ability and capacity to absorb impact make it valuable across many industries, and compression, whether intentional during manufacturing or incidental during use, has a significant effect on these properties and on how the finished product performs.

Quick Reference: Key Compression Terms

Types of Foam

There are many types of foam, each with distinct properties. The type used in a product determines how it responds to compression, and so which uses it suits.

Polyurethane foam, for example, is a versatile material used in everything from mattresses to automotive interiors. It is known for its durability and comfort, and its compression characteristics can be adjusted during manufacturing to create products with different levels of firmness.

Ether and Ester Foams

Ether and ester foams are two types of polyurethane foam. Ether foam is typically softer and more resilient, making it the usual choice for comfort applications such as bedding and seating. Ester foam typically has a firmer, more uniform cell structure and greater strength, making it suitable for packaging and industrial uses.

Both can be produced with different compression characteristics, so manufacturers can tailor the foam to the application. This versatility is one reason polyurethane foam is so widely used.

Memory Foam

Memory foam is a type of polyurethane foam known for its viscoelastic properties: it softens in response to heat and pressure, moulding to the shape of whatever is pressing on it, and slowly returns to its original shape once the pressure is removed.

These compression characteristics make memory foam ideal where pressure relief and support are needed, such as mattresses and pillows. However, its slow recovery can make it less suitable as the main foam in applications that need a quick rebound, such as seating.

Compression Testing

Compression testing is an important part of foam production. A known force is applied to a foam sample and the amount it compresses is measured, giving valuable information about the foam’s firmness, resilience and durability. See our guide to foam testing.

Different tests measure different aspects of how foam behaves under pressure. Compression force deflection (CFD) measures the force needed to compress a whole sample by a set percentage of its original height (BS EN ISO 3386 in the UK and Europe). Indentation force deflection (IFD), also known as indentation load deflection (ILD), measures the force needed to press an indenter into the foam by a set amount (BS EN ISO 2439).

Compression Set

Compression set is the extent to which a foam fails to recover its original shape after being held compressed. A high compression set means the foam is likely to become permanently flattened over time, reducing its effectiveness and lifespan.

Compression set is measured as a percentage, and a lower percentage means better recovery. It is a critical factor when choosing foam for applications involving repeated or prolonged compression, such as seating or bedding.

Compression Fatigue

Compression fatigue is the gradual loss of a foam’s ability to resist compression over time. It is caused by repeated cycles of compression and release, which break down the foam’s cell structure and reduce its resilience.

Compression fatigue is a major concern where foam is compressed frequently or heavily, such as automotive seating or industrial equipment. Foam for these uses must be designed to withstand it, often by using high-density foams or additional reinforcement. See our guides to foam density and foam durability.

Applications of Foam Compression

Foam’s ability to absorb impact and provide cushioning makes it ideal for many products, from furniture to packaging, but the compression characteristics needed vary greatly by application. A mattress needs foam that gives comfort and support over a long period, while packaging may need foam that absorbs a high level of impact without becoming permanently deformed.

Furniture and Bedding

Foam is widely used in furniture and bedding for its comfort and durability, and its compression characteristics are critical to performance. A mattress must withstand repeated compression from a person’s body weight while still providing support and comfort.

Similarly, seat foam must resist compression fatigue from repeated use while still providing enough cushioning. The type of foam, its density and its firmness all determine how well it meets these requirements. See our guide to foam cushioning.

Packaging Materials

Foam is widely used in packaging because it absorbs impact and protects delicate items. Here the foam must absorb a high level of impact without becoming permanently deformed.

The type of foam depends on the packaging requirements: high-density foams may be used for heavy items and softer foams for delicate ones.

Choosing the Right Foam for Your Project

• Seating and bedding: Choose foam with a low compression set and good resistance to compression fatigue, at the right density and firmness.
• Pressure relief: Memory foam, accepting its slower recovery.
• Comfort applications: Softer, more resilient ether foam.
• Packaging: High-density foam for heavy items and softer foam for delicate items.
• Comparing firmness: Check CFD or IFD/ILD values.

Final Thoughts

Foam compression plays a critical role in the performance of foam products. From the type of foam to the compression characteristics required, every aspect can have a significant impact on the final product. Whether you are a manufacturer, a product designer or a consumer, understanding foam compression will help you choose and use the right foam for your needs.

Explore Related Foam Guides

Continue exploring foam performance and specifications across our glossary:

• Foam Testing: The tests used to measure firmness, density and durability.
• Foam Resilience: How quickly foam returns to its original shape after compression.
• Foam Density: How mass per cubic metre affects support and lifespan.
• Foam Durability: What makes foam last longer in daily use.
• Foam Cushioning: Matching foam firmness to seating and comfort.
• Memory Foam: How viscoelastic foam contours to the body.

Need Foam That Holds Its Shape?

Whether you are replacing flattened sofa cushions or specifying foam for a new seating project, the Foam & Covers team can help you choose a foam with the right firmness and recovery, and cut it precisely to your measurements.

Contact Our Foam Specialists or Order Custom Cut Foam Online .