What is Foam Rubber?

What does “foam rubber” actually mean?

Foam rubber is what you get when a foaming agent expands rubber, or a rubber-like polymer, into a network of tiny air pockets. The result is soft, light and compressible compared with solid rubber, while keeping much of its flexibility and resilience.

In everyday conversation, people use the term loosely to mean almost any cushioning foam. It dates back to 1929, when Dunlop Rubber chemists first created it by whipping natural latex. For decades it really was rubber. Today it’s an umbrella term covering a family of related materials, not one specific product.

Foam rubber or rubber foam, does it matter which way round?

No. “Foam rubber” and “rubber foam” describe the same thing, just in a different word order. Both mean rubber, or a rubber-like polymer, that’s been expanded with a foaming agent into an air-filled structure.

What are the different types of foam rubber?

What “foam rubber” means in practice depends on which type you’re actually looking at:

Material and composition

Feel and typical uses

Which type does GB Foam Direct use, and why?

We generally offer two main types of foam rubber: polyurethane (PU) foam, used for furniture, cushioning and mattresses, and polyethylene foam, such as our Plastazote closed cell foam, used for things like packaging, protective casing and applications where water and chemical resistance matter more than cushioning comfort. Browse our upholstery foam range for PU foam options. If you’re looking for another type of foam, contact our team directly. We have a robust supply chain, sourcing foam from over 40 leading manufacturers worldwide

PU foam isn’t the same material as latex or neoprene, but it’s the one that fits furniture and cushioning applications best: durable, available in a wide range of firmness grades, and available cut to any size you need. If you’re replacing worn-out cushions, our replacement sofa cushions range covers the shapes and grades most people need; we even have a custom shape option for anything less regular. For closed-cell needs, see our Plastazote foam range.

How is it made?

During manufacturing, a foaming agent is introduced into the base material, which is rubber, latex or polyurethane depending on the type, giving it an air-filled matrix structure. The polymerisation process can take anywhere from a few seconds to a few minutes, depending on the polymer used.

The chemicals are mixed in a mixing head, generally an automated process, then poured onto a conveyor belt to cure. As it travels along the belt, it forms a continuous block which is cut using a horizontal band saw. Those blocks are then delivered to foam converters, like us, who cut them into the shapes and sizes customers actually need.

What is it used for?

Foam rubber, in its various forms, turns up in more places than most people realise: furniture and sofa cushions, mattresses, caravan cushions, vehicle seating, acoustic treatment, packaging, and industrial sealing and gaskets. We cut foam to over 24 template shapes, plus a custom option for anything that doesn’t fit a standard template.

Frequently asked questions

Is foam rubber the same as memory foam?

Memory foam is a type of foam rubber, specifically a subtype of polyurethane foam. But it’s chemically distinct from standard PU foam: memory foam is formulated to compress and recover slowly under body heat and pressure, while standard PU foam (the kind used in most sofa cushions) responds and recovers almost immediately.

Is foam rubber waterproof?

It depends on the structure. Open-cell foams (most upholstery and mattress foam) absorb water because the air pockets connect to each other. Closed-cell foams, where each air pocket is sealed, are much more water-resistant. That’s why closed-cell materials like Plastazote are used for some outdoor and marine applications where water resistance is key.

There’s a third option built specifically for outdoor cushions: reticulated foam. It’s still open-cell, but the pores are large enough that water drains straight through rather than being absorbed and held, so cushions don’t stay soggy or develop mould. That’s why it’s used for marine and outdoor cushions specifically, rather than closed-cell foam; comfort and drainage, not sealing water out entirely.

Does foam rubber degrade over time?

All foam softens gradually with use, but the rate depends heavily on the grade and density you start with. Higher-density polyurethane foam holds its shape for years longer than low-density or budget grades under the same use.

What’s the difference between foam rubber and sponge?

In everyday use the terms overlap a lot. “Sponge rubber” is often just another name for open-cell foam rubber. Where a distinction is made, “sponge” tends to refer to softer, more absorbent open-cell material, while “foam rubber” is used more broadly across both open- and closed-cell types.

Can foam rubber be cut to a custom size?

Yes. That’s the core of what we do. Choose a template shape or provide your own custom measurements, and we cut to your exact size and shape, with next-working-day delivery as standard on orders placed before 11am Monday to Thursday.

Is foam rubber the same as polyurethane foam?

Polyurethane foam is one type of foam rubber, not a separate thing. When most people in the UK say foam rubber in the context of furniture, cushions or mattresses, polyurethane foam is what they actually mean, which is why it’s the material we cut.

Cameron Holland

Cameron has emerged as a key marketing expert since joining GB Foam Ltd in 2017. A graduate of the University of Winchester, with a professional background in Public Relations; he has combined his content writing and brand awareness expertise with an in-depth knowledge of foam products and foam conversion technology to enhance the company’s marketing strategies and industry presence. Cameron has led numerous marketing campaigns, in both B2B and B2C segments, to further brand recognition and open up new business avenues worldwide.