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Differences between open and closed cell foam mattresses, Guide,



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Open and closed cell foams

Foam is a very integral material in the mattress industry. It is used quite commonly in mattresses, but there is a crucial type of foam difference that you likely have come across, but been unsure about what it meant; that is open cell structure and closed-cell structure. What’s pleasing to know is that the names give you a lot of information from the start, but there are technical aspects that play a role in defining the differences between the two types. These can be found in the manufacturing process, the chemical elements used in their production and the resiliency or strength they bring to the foam they are used in. 


What open cell foam is

Open and closed cell structure depends on how it is manufactured. Open-cell foam is a technology that is synonymous with polyurethane or polyfoam It is made with inflating agents which produce a gas that expands the rubber. A foam is normally considered to be open-cell if more than 50 % of its cells have become open. It is worth noting that it is quite uncommon for materials to use a 100% open-cell structure and the same goes for closed-cell structures. The cell is referred to as open when they permit air or water to fill its opening which will adapt its properties and the walls are not enclosed. In the case of mattresses, of course, it is air, usually that enters these openings and this is important for how the foam behaves. Open-cell foam, due to its structure reduces the amount of off-gassing that can occur with your mattress, concerning other foam mattresses. In short, off-gassing is a by-product of foam manufacturing. It is the release of gaseous substances known as Volatile Organic Compounds which although considered to be harmless do create an unpleasant smell and that is what open-cell foam keeps to a low level. To learn more about Off-gassing and see what kind of mattress is likely to produce check out the link.

Production of open cell foam

How open-cell foam is made

You don’t have to be a professor in chemistry to see how the process of open-cell foam production inspires the behavior of the foam. We’ll explore it now:
The expansion of the foam cells occurs in a process which is known as vulcanization. This is a kind of synthesis that modifies natural rubber by heating rubbing with sulfur and combining the components chemically, using high temperatures of up to 180 degrees. However, sometimes other compounds are used in the process such as zinc oxide which basically acts as the interlinking bridge between the rubber and the sulfur when combined with other compounds, which accelerates the process or allows for the chemical procedure to be undertaken efficiently at lower temperatures. This chemical reaction significantly enhances the quality of the new and improved rubber. This refined, synthesized rubber is stronger and more resistant than it was before the vulcanization. This is important because this ensures that the rubber can remain intact when it experiences expansion. Therefore, vulcanization is key in the development of foam in mattresses that are more durable and resilient and Evlon foam is a type of foam that demonstrates just that. 

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How open-cell affects a mattress

Since open-cell foam is the construction of foam cells to let in air, open-cell mattresses are very responsive. Its capacity for free air circulation means that they have the potential for a lot of springiness. It is why open-cell foam mattresses can compete with pocket-spring mattresses with how they respond to movement and pressure variation when someone is sleeping on them. Whilst  pocket-spring mattresses use sheathed coils to compress and decompress to adjust to the pressure points and weight of an individual, open-cell foams generally are made in such a way that they compress and return to their original form with ease. The airflow and openness of the cells make the mattresses quite soft and conformotive. Furthermore, the unrestricted air flow equates to better breathability, so heat retention is moderated and the temperature of the mattress is prevented from reaching levels that will disturb your sleep. 
Many open-cell structures are reticulated which means that the rubber can have more voids than walls and in effect be made up more of the lack of matter than actual matter. This unsurprisingly can help you with sleep because an open-cell structure made in this way will almost be like you are literally sleeping on air. 

Open and closed cell foams

What Closed-cell is

The closed-cell structure has that name because the cells in the foam are completely closed off and sealed shut by their walls, so they do not really socialize with other cells in the foam. Unlike open cells, there is no opening for water or air to enter and flow. For this reason, closed-cell technology is used often in sealing off the flow of gas and liquid substances. Since they are that powerful in this regard, as well as in mattresses they are used in the marine and automotive industries where electrical components need to be protected. This fact highlights the water-resistance of closed-cell structures. Also, EPDM rubber which is an example of closed-cell foam is highly-resistant to heated water vapor, acids, and alkalies and is even able to insulate electricity, exemplifying the level of resistance closed-cell structures have to numerous substances and why the closed-cell mattresses can withstand a lot of elements that wear down other kinds of mattresses. 

How closed-cell foam is made

Closed-cell structures are usually produced by placing the rubber under high-pressured expulsions of a gas such as nitrogen. It is when the two components come together that the closed-cell foam gets its water-resistant capabilities. Gas bubbles are created when the material transitions from a liquid to a solid and it is these gas bubbles that contain pockets of air. 

Open Cell v Closed cell head to head

Surface durability

 Closed-cell is better. Open cell is quite vulnerable to surface damage and can be worn down by Ultraviolet light easily if not protected. Closed-cell structures are highly resilient. 


As the walls in closed-cell structures are closed off, this leads to heat retention, since no air can be circulated. As airflow is restricted, breathability is not a strong point in these kinds of mattresses and they are not great for moderating temperatures as trapped air means heat can rise. A mattress that excels with this because it uses an open-cell structure is the Simba Hybrid mattress 

Simba Hybrid

The verdict

The Simba Hybrid is a well-acclaimed mattress that lives up to the hype in most regards. It's Simbatex graphite-infused, open-cell  foam layer makes the breathability and thermal regulation  of the mattress exceptional, so you wouldn't have to worry about the sleepless nights due to heat build-up and sweat discomfort. In addition it really delivers with edge-support due to its edge lift technology which gives the entire mattress a sturdiness. Though you should beware of the sagging that seems to occur in this mattress after a while and consider other options if you are heavy stomache-sleeper, there is a lot that the mattress impresses with. 

Our grading of the Simba Hybrid

Simba mattresses reviewed
Simba Hybrid

You want to buy one of Simba’s Hybrid range mattresses whilst on a budget. Cheaper than the Simba Hybrid pro and Hybrid Luxe.

4 / 5
star star star star Open and closed cell foams

Simba Hybrid: Pros and Cons

We appreciate

    You are a light to average weighted stomach sleeper 

  • You are a sleeping couple who are  sensitive to motion elsewhere on a mattress.
  • You sweat quite a lot when you sleep and need a cover to remove moisture as well as keeping you cool
  • You need assistance with spinal alignment and can’t afford any back problems created during your sleep. 

We regret

  • You have a sleeping partner and will need and don’t want the disturbance of motion from another side of the mattress. For that we recommend the ‘Emma original’ memory foam mattress. This Emma mattress isolates ripples of motion very well.
  • You are a heavy sleeper or weigh above the average. For that we recommend the ‘Dreamcloud Luxury Hybrid
Open and closed cell foams


Open-cell structure foam is great at absorbing moisture due to the absence of cell walls. This doesn’t mean, though, that it traps moisture, but rather its composition means that it excels at being able to move moisture on, which equates to having moisture-wicking properties. Closed-cell structured foam on the other hand has high water-resistance qualities. Open-cell foam needs to be compressed to be water-resistant, but closed-cell structures don’t. However, this means the absorption of closed-cell foam is low and it is not as great at moisture-wicking. 


Generally, open-cell structures are more comfortable because of their super-softness and plushness. Closed-cell structures tend to be very firm which can be important for support, but open-cell structures can be adapted to offer firmness too, but with more balance. 

Responsiveness and springiness

Closed-cell structures are quite rigid and don’t offer much adaptability. However open-cell structures often compress and decompress quickly with the ultimate adjustability concerning the amount of force it is subjected to. 

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