Closed Cell vs Open Cell Foam: A Detailed Comparison

Rubber is used in a wide variety of places in our lives. The soles of your shoes, the tyres on your car or scooter. Did you know that rubber is also used to make the sponges you wash the dishes with, and also tiles you can put on the floor to give you comfort when you walk. Dish sponges are open celled foam, and neoprene floor tiles are closed cell foam.

They are made in similar ways but with some key differences, and it’s these differences that are key to their individual usefulness. As top-level foam suppliers in Australia, MSTOR understands these differences, and through this article we’re going to explain how each type of foam is made and used, and what the differences between them are.

How is Foam Made?

Both open cell and closed cell foam are made the same way, more or less. They are made by mixing liquid polymers, such as silicones, acrylates or polyethylene glycols with catalysts, surfactants and blowing agents. This triggers an exothermic reaction and forms bubbles. In open celled foam the bubbles burst, and with closed cell foam the bubbles stay intact.

Open Cell Creation

Process . The reaction mixture expands rapidly and during the curing process the cell walls burst.
Structure . This process forms an interconnected structure of struts which looks like a mass of popped bubbles.
Blowing Agents . This process typically uses water as a blowing agent. This helps create a lightweight breathable material.

Closed Cell Creation

Process . Gas is trapped inside the liquid polymer mixture as it expands slowly.
Structure . The cells are packed tightly together and sealed. This stops air and moisture from passing through the material.
Blowing Agents . Special chemicals are used in the blowing process so the cell walls remain intact.

If you want to buy foam sheets, heatproof foam or model foam in Melbourne, browse our collection of foam. Contact us for more information. We can cut foam to order , and supply to anywhere in Australia.

What is Closed Cell Foam

We’ve described how closed cell foam is made above. But what is it? It is a dense rigid material, or semi-rigid material that is sealed and the cells, the bubbles, are not connected inside the material.

The disconnect between the bubbles makes closed cell foam waterproof, airtight and incredibly buoyant. It is also a good thermal insulator, which makes it a superior material for marine use and construction applications.

Features of closed cell foam are:

Waterproof and airtight . The sealed cells inside the structure mean this product doesn’t allow water or air to pass through. It resists moisture and mould as well.
Structurally strong . It is a rigid and dense material, more so than the open cell foam. This means it can add structural strength to applications. For example, closed cell foam is used as a base for carpets to both provide rigidity, and waterproofing.
Good Insulation . Closed cell foam has a high R-value*, giving it a great heat resistance.
Density . Dense and firm to the touch, so closed cell foam is an excellent shock absorber. You would see closed cell foam mats in gyms and dance studios.
R-value is a measurement of a material’s thermal resistance or its ability to restrict heat flow. The higher the number R-value the better the thermal performance. R value is determined by dividing the material’s thickness (d) by its thermal conductivity (k)-

Where is Closed Cell Foam Commonly Used

Closed cell foam has many uses, particularly due to its waterproofing and heat resistant qualities. It is also highly durable and can take a beating.

Insulation . For hard-to-reach areas, closed cell foam makes a fantastic insulator. Being air-tight and water tight, plus having a high R-value makes it a perfect insulator for homes and businesses.
Marine and automotive . Good for marine insulation , boat cushions and flotation devices in an emergency. It makes excellent gaskets and sealing because it does not absorb water or permeate water.
Packaging and protection . Due to the stability and firmness of closed cell foam, it makes great packaging for delicate and fragile items.
Sports and recreation. Yoga mats, floors in gyms and dance studios, protective gear like knee pads and chest protection.
Industrial and DIY . Soundproofing rooms for drummers and sound recording, sealing for HVAC and small home sealing jobs.

What is Open Cell Foam

Open cell foam is a lightweight material which is incredibly flexible. Made up of lots of connected bubbles, it looks more like a lattice-like structure rather than a mass of burst bubbles. It is incredibly breathable and allows moisture to pass right through.

Being so breathable means open cell foam is very compressible and makes great cushioning and filtration.

Key features of open cell foam include:

Structure . The cells are popped bubbles ,and the foam is intentionally created this way. This results in the soft, squishy material that is very flexible and malleable.
Permeability . This type of foam is absolutely not air-tight or water-tight, quite the opposite. This allows vapour to pass through.
Durability . The less dense material and open bubbles mean this type of foam is not durable at all. It wears out much faster than closed cell foam.
Cost . It is easier and cheaper to produce open cell foam.

What Applications Does Open Cell Foam Have

The biggest applications for open cell foam is for insulation in homes, soundproofing rooms and cushioning. It is also used for cushioning and foam mattresses and pillows.

Main uses of open cell foam:

Insulation . Often sprayed into wall cavities or into ceiling cavities for insulation. It lets heat and air through but at a slower pace. Also an excellent noise-cancellation material for media rooms and internal walls.
Furniture and bedding . Being so comfortable and soft it is often used with memory foam mattresses and pillows and seat and lounge cushions .
Industrial uses . Often used in air filtration systems, specialised packaging and some protective gear.
Other uses . Seats in cars and trucks and cleaning products like your dish sponges.

Comparison at a Glance

Feature	Open-Cell Foam	Closed Cell Foam
Density	Soft and spongy	Rigid
Waterproof	Very permeable, soaks up water	Highly waterproof
R-value	Low	High
Expansion	Can expand over 100x original size	Low. Solid material
Cost	Very affordable	Costs more
Best use	Interior walls and noise-reduction	Marine spaces, high-impact sporting zones

When comparing open cell and closed cell foam, you can look at factors such as structure and cost, however they have such different applications in the real world, it would be rare that you would have to make the choice between them.

The three big differences between open cell and closed cell foam are

Closed cell foam is much more rigid than open cell foam.
Closed cell foam is waterproof while open cell foam is breathable and permeable.
Closed cell foam has a higher R-value and is therefore much more fire resistant.

The experts at MSTOR can help you buy foam sheets for your home or your business, if it’s for heatproof closed cell foam or high quality modelling foam . Contact us today to speak with the best foam suppliers in Melbourne.

FAQ

Q: Which foam types at MSTOR are closed cell?

MSTOR stocks several closed cell foam options. Closed cell foam is available in types including Neoprene, EVA, and PE foam, all of which share the tightly sealed cell structure that provides moisture resistance and structural strength.

Q: Can closed cell foam handle chemical exposure?

Yes. IXPE closed cell foam has good chemical resistance, good UV properties, good heat insulation, and good resistance to aging and high temperatures. EPDM closed cell foam similarly offers broad chemical resilience.

Q: Is closed cell foam resistant to mould and bacteria?

Yes. IXPE closed cell foam is non-irritant, odourless, and with its vapour resistance, will not support mould or bacterial growth. This property is common across MSTOR's closed cell range, including PE and EVA foams.

Q: Can I get open cell or closed cell foam cut to custom sizes from MSTOR?

Yes. MSTOR can provide expert guidance tailored to your project needs, and custom thicknesses and sizes are available upon request. Whether you need open cell foam for upholstery or closed cell foam for industrial insulation, MSTOR's custom cutting service can accommodate your exact specifications. You can reach their team at sales@mstor.com.au .

Q: Does MSTOR ship Australia-wide?

Yes. MSTOR ships products to all states across Australia, including Melbourne, Sydney, Brisbane, Perth, and Adelaide. Free shipping is available on orders over $150 for customers in VIC, NSW, QLD, SA, and ACT.

Q: What industries does MSTOR cater to?

MSTOR serves a wide range of industries including automotive, construction, medical, packaging, schools, restaurants, and government sectors. Their diverse product range is designed to meet the unique demands of each industry.

Q: What services does MSTOR offer beyond product supply?

In addition to supplying foam and tape products, MSTOR offers tape slitting, foam cutting, and laminating services. These value-added services allow customers to receive materials that are ready to use straight out of the box.

Q: How do I choose the right foam for my project?

Start by considering the specific requirements of your application, like the need for cushioning, insulation, water resistance, or structural support. Then factor in the working conditions (e.g., heat, chemical exposure) and your budget. MSTOR's team of experts is available to provide consultation and help you make the right choice.

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