Open-Cell vs Closed-Cell Foam: What's the Difference?

Given how versatile foam is and how many uses it has, there's a huge selection of foam types, each with its own uses, material benefits and composition. One of the most common questions we receive at eFoam is "what is the difference between open and closed-cell foam?" Knowing the difference between these two structures is a good place to start.

The structural difference

The first difference is fairly obvious: one has an open-cell structure, the other a closed-cell, bubble-like composition. In open-cell foams the structure is almost free-flowing and holds pockets of air, which affect the feel and performance. Closed-cell foam has pockets completely sealed off from air, giving it a more solid feel.

How they feel

Open-cell foams typically feel softer, less firm and very springy, whereas closed-cell foams are firmer, more rigid and have less spring. It's worth noting that not all cells in an open-cell foam need to be open for it to be classed as such: a foam with a mixed open and closed structure is still termed open-cell, but will be a little firmer than a wholly open one. A common misconception is that the difference in structure equates to thickness or density – it doesn't – though it does influence where each type is best used. For more on this, see our guide to foam density, weight and firmness.

Where open-cell foam is used

Open-cell foams are fantastic for furniture and mattresses where comfort is key, and are commonly used in upholstery such as sofas, cushions, car seats and support items. They're available in a range of densities to suit various comfort levels, from incredibly soft to very firm and dense.

Where closed-cell foam is used

Closed-cell foam is popular where firmness and resistance to the elements matter. As outdoor furniture grows in popularity, closed-cell foam is the perfect seating filler thanks to its water resistance. Its rigidity also makes it ideal for packaging that needs security and protection, and its composition makes it a fantastic insulator – it's not uncommon to see closed-cell foam in building insulation and in electrical and heating components that need protection and lining.

Both types are incredibly durable; the choice ultimately depends on the application, as closed-cell is tougher against rips and tears while open-cell offers unparalleled softness. For guidance choosing between them, please contact our friendly advisers.

Frequently asked questions

What is the difference between open-cell and closed-cell foam?

Open-cell foam has an almost free-flowing structure that holds pockets of air, making it softer and springier. Closed-cell foam has pockets completely sealed off from air, making it firmer, more rigid and water-resistant.

Which is more durable, open or closed-cell foam?

Both are highly durable, and the right choice depends on the application. Closed-cell is typically tougher against rips and tears, while open-cell offers unparalleled softness.

Where is closed-cell foam used?

Closed-cell foam suits uses where firmness and resistance to the elements matter: outdoor furniture (its sealed structure resists water), packaging needing security and protection, and insulation, including in buildings and electrical or heating components.