Open Cell Vs Closed Cell Foam: The Ultimate Guide 2023

There are a lot of foam material types and ways to categorize them. For you, all foam materials can either be closed cell foam or open cell foam. For a short period of time, it might be hard to figure out what they are. In this post, you’ll learn what open-cell foam is and what closed-cell foam is. Plus, you’ll learn how the 2 different types of foam compare, so you can choose the right one.

What is open cell foam?

Open-cell foam is a type of foam classified by its physical structure. R-value of open cell foam is around 3.5 per inch, Pore sizes of open cell foam range from 0.5 to 3mm, and the pores are connected or completely connected, creating a single-dimensional or three-dimensional structure through which gases and liquids can pass.

Open cell foam materials are versatile, lightweight, and durable, so they’re a good fit for many industries. Open cell foam has these features and benefits:

• It doesn’t contain VOCs or ozone-depleting gases
• It minimizes noise transmission
• Most foreign particles get trapped in its pore spaces, so it’s perfect for reducing dust and allergens
• It’s mold-resistant
• It’s good for soundproofing
• It has a good insulation value of R-4.21 per inch
• It’s about 40-50% of heat gain/loss in apartments
• It won’t break, shrink, or fade over time
• It’s got a lot of expansion potential, and it can grow up to 100 times
• There’s a low density of between 0.4 and 1.2 lbs./ft3

What is open-cell polyurethane foam?

Open cell polyurethane foam is one of many types of polyurethane synthetic materials. It is characterized by its porous nature, and therefore its low density, light weight, good heat and sound insulation, high specific strength, vibration dampening, and other great properties. With different raw materials and formulations, it can be made into a soft, semi-rigid, or rigid foam.

Polyurethane is any polymer containing repeating -NHCOO- groups in the main chain. Most polyurethane is made by combining organic isocyanates (usually toluene diisocyanate, TDI, for short) with polyol compounds (polyether polyol or polyester polyol).

Polyurethane foam is one of the most commonly used open cell foams. Their versatility allows them to be used in a wide range of industries and materials, like open-cell foam insulation, furniture upholstery, seat cushions, medical packaging, electronics, power equipment and much more.

What is Closed cell foam?

A closed cell foam is tough and flexible plastic rubber made up of tiny pores and cells. There’s no connection between the cells in the closed cell foam. Closed cell can be compared to a net filled with bubbles, where the bubbles are trapped tightly against each other, but they’re not interconnected.

Closed cell foams are also more frequently used in multiple industries, including construction, packaging, marine, electronics, automotive, and so on. Closed cell foam materials include EVA foam, Polyethylene foam, Neoprene foam, PVC/ Nitrile foam rubber, SBR foam rubber, etc.

Closed cell foam has these advantages:

• Helpful and reliable both inside and outside
• Strengthens the structure
• Best for providing sound and heat insulation
• Reduce vapor transmission effectively
• Water-repellent material
• Excellent leak resistance

Comparison of open cell vs closed cell foam

Foam is a cellular product. Structure and content of the cell, whether open or closed, greatly influence a product’s performance.

Despite their similar looks, open cell foam and closed cell foam are two totally different products.

Unlike closed-cell foam, which contains more than 90% closed cells, open-cell foam, for which there is no official definition, typically contains less than 20% closed cells, but it may have higher proportions. Both open cell and closed cell foam have similar properties, such as shock absorption, thermal insulation, and noise reduction. In general, a closed cell content (CCC) directly influences the fundamental properties of the foam, such as tear strength, thermal conductivity, average density, water absorption, watertightness, vapor permeability.

Here are the main differences between open cell foam and closed cell foam are:

Structure of foam

Closed cell foam and open cell foam seem to have different foam structures. Closed cell foam is made up of tiny closed cells that look strong and solid. Open cell foams are uneven and lightweight, so you can see the openings all around the material.

Density of foam
Open cell foam is usually lighter than closed cell foam. Compared to open cell foam, closed cell foam keeps almost its initial weight before foaming, but open cell foam can’t. The open cell structure has lost a lot of weight after foaming.

Resistant to moisture, air, and liquids

Here’s another way to tell closed cell foam from open cell foam. Just put a little water on both kinds of foam and you’re done. You’ll find out one type of foam absorbs water and takes it in. But the rest don’t absorb water and keep it out. Now you know the first one is open cell foam and the rest is closed cell foam.

Open cell foam has voids that intersect, making paths through it. Unlike open cell foam, closed cell foam has individual closed areas, so air or liquid can’t penetrate it. Because their foam structures are different, they perform differently in the presence of moisture, water, air and other liquids.

Cost of materials
Open cell foam is usually cheaper to use. Polyurethane foam and reticulated polyurethane foam are the most popular open cell foam materials. Since they’re so cheap, they’re often used for upholstery, seat cushions, carpet underlayments, and foam filters. Closed cell foam usually provides better insulation and durability, but also costs more.

Insulation and soundproofing
Closed cell foam can usually outperform open cell foam when it comes to heat insulation. Closed cell foam is less thermally conductive than polyethylene foam, so they can be used for roofing and flooring insulation. 

In the meantime, open cell foam offers better sound absorption than closed cell foam. As they have lots of tiny open cells, which can make them very powerful and effective at absorbing noise. You can find open cell convoluted PU foam used as sound proof foam in broadcasting studios and conference rooms etc.

Application Differentiation
Foams with open cells are generally soft and compressible. Foam with open cells traps air well, acting as a good insulator. Open-cell foams, like a sponge scourer, can absorb liquid. In addition to providing greater structural rigidity, closed cell foams can be filled with other gases besides air during manufacture. Water or air can’t move from one spot to another with closed cell foam. Also, open cell foam is great for sponges because it absorbs. Because of its low cost, open cell foam is also used for insulation. Foam with open cells can also be used for sound dampeners, shock absorbers, cushions, and pillows.

Foam with a closed cell structure is used in flotation devices because it doesn’t absorb water and trapped air gives you a boost. And closed cell foam is often used in other applications that require water resistance, like neoprene suits, mats, gaskets, and insulation. Open cell foam is denser and generally more expensive.