Foam Vs Spring Mattress- The Basics

Inside The Mattress | by Tyler Peh | 15-Oct-2019

Foam Mattress vs Spring Mattress

When developing and designing the Woosa Mattress, we posted ourselves the age-old question everyone asks when buying a mattress- springs or foam? Which would work better as a foundation base for the perfect mattress?

In this 2-part blog post, we will be focusing on the bed’s main core, and list down the priorities we considered when building the Woosa Mattress- durability, low partner disturbance, even weight distribution, deep level support and overall affordability.

Understanding Springs:

Springs often form majority of the mattress cores in the market today, and come in many forms. Usually made from steel or more premium titanium alloy, these coils are usually wrapped and encased in fabric and layers of foams. The main differentiating factor between spring mattresses are the number of springs (ranging from a few hundred to thousands of small springs), the thickness (gauge) and how they connect with each other.

Pros:

Higher overall durability
Generally more affordable
Does not sag
Generally cooler if less layers of foams are used

Cons:
Makes a heavy mattress
Poor quality springs may pop up and cause discomfort
Uneven support
Spring vibration and motion transfer

 

Bonnell Springs
Bonnell springs are the oldest spring types and commonly seen in entry level mattresses. The springs are hour glass shaped, tied together using spring wire and reinforced using a thick border wire to retain its shape. Bonnell springs are cheap with poor durability, and have high levels of motion transfer.


Continuous Springs
Continuous Springs, Mira-Coils or Continuous Coils are essentially the same thing, one continuous coil in an up down fashion to mimic individual coils. They are slightly better at eliminating motion transfer and offer better support than Bonnell springs, but are still generally avoided in higher quality mattresses.

Pocketed Coil Springs
The most commonly seen form of springs in the mattress market, pocketed coils are individually wrapped coils usually encased in foam, reducing motion transfer and offers more localized support. Pocketed coils come in different coil counts and sizes and have varying durability and supportive properties. Smaller, micro coils are known to have poorest durability simply due to the physical nature of the coils, as compared to larger, thicker gauged pocket coils.

 

Understanding Foams:

Foam cores come in a large variety, from PU foam, Latex foam, to Memory foam. They usually come in a single block, and unlike springs, work by utilizing air trapped between its molecules to provide support and bounce. Foam quality is usually categorized by density, with higher density foams attributed to higher quality.

Contrary to popular belief, a high-density foam does not equate to a higher firmness. A high density foam usually means that a higher amount of materials (or mass) is being compacted per unit volume. More material per unit volume means a higher price, and better overall quality and durability.

Pros:

Offers good support
Even weight distribution
Reduces motion transfer
Can be hypoallergenic- minimizes space for dust mites to thrive

Cons:

Temperature sensitive
Poorly made foams may sag over time
Off gassing- poorly made foams may produce a pungent smell when new

Memory Foam Core
Memory foam is seldom used as a mattress foundation, with the exception of full memory foam mattresses. The foam deforms and retains its shape under pressure and bounces back slowly, which is great for pressure reliving. Memory foam itself offers literally zero bounce, which is a double-edged sword- it makes it hard for users to toss and turn at night, but in return is excellent for reducing motion transfer in a mattress. Due to it’s added viscosity boosters, memory foam tends to trap heat, which may cause the entire mattress to feel hot especially when used in thick quantities as a foundation base.

Polyurethane Foam Core
One of the most common materials used in mattresses and especially as a core. PU foam is usually classified under 3 categories by density: regular PU, high density, and High Resiliency, with the latter being the highest quality.  Many varieties of PU foam exists, with some infusing other materials such as charcoal or cooling gel. However, rarely do companies use modified PU foams for the mattress foundation cores.

High density Foam= at least 30kg/m3
HR foam = at least 50kg/m3

Unlike memory foam, PU foam is bouncy, springier and structurally firm, which makes the mattress more responsive. PU foam is also the cheapest to produce compared to Memory and latex. However, overall durability may be affected especially with lower density PU foam bases.

Latex Foam Core
Often used as a core for pure latex mattresses, latex is widely researched to be the most balanced mattress material- highly durable, offers an adequate amount of bounce and support, and does not trap much heat.  However, a solid latex core is extremely expensive to produce, which is the main reason why many mattress companies avoid using it as a foundation. We will discuss in detail the key differences in the types of latex in a future blog post.

 

In Part 2 of our blog post, we’ll go through our thought process when selecting a suitable mattress core for the Woosa Mattress.

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