The truth About Foam & innerspring Mattresses FOAM INNERSPRING

The Truth About Foam

Almost all bedding contains polyurethane, latex or memory foam cushioning. But not all foams are alike, and it can be important for you to know more about this product and the terminology used to describe its important characteristics. So let's start out with a glossary of basic terminology.


Density is a measurement of mass per unit of volume and it is expressed in pounds per cubic foot. Although foam production conditions can affect the long-term performance of various foams, density is generally considered to be the most important indicator of durability. Higher density foam is generally less likely to bottom out, fatigue or show body impressions. The higher the density of the foam the more expensive it is to produce due to greater material content.

IFD / Indentation force deflection

This technical sounding term is simply a measurement of foam firmness. IFD is generally measured in 2 ways; Surface firmness is measured by compressing a 4" thick sample of foam by 25% with this measurement being calculated in pounds. This 25% measurement usually ranges from 10 pounds to 45 pounds. The higher the number the firmer the foam.

The second measurement is taken by compressing the foam to 65% of its original height and then used to form a ratio referred to as the support factor.

It's important to remember that foam firmness is independent of density. It's possible to have a very high density foam that's very soft, or a low density foam that's very firm. Just because a foam feels firm doesn't mean it's necessarily high quality.

Convoluted Foam

This is a foam fabrication process involving the use of special cutting equipment to produce “egg carton” dimples in the foam. This process is often used in topper pads and cushioning close to the surface. The dimples can be used in a face down or upward facing application.

Soy Based Foam

Most foam manufacturers today are working to add soy derivatives to their petrochemical based mix of foams. This is an environmentally friendly approach to what has been a very petrochemical dominated field. As technology improves the % of reactive sustainable material in the actual product has grown. If this is an important concern for you it would be a good idea to study this further and ask questions regarding the content of sustainable material in these foams.

Foam Posturization

This simply refers to foams that have a mixture of firmnesses represented on the same sleeping surface to create greater firmness, resistance, resiliency or comfort in the center or largest weight bearing areas of the mattress surface. This is done by changing the foam fabrication to vary ILD’s or specialized cutting or molding of the foam surface.

Foam Types

That leads us to a discussion of the various types of foams. There are 3 major foam types used in mattress manufacturing: polyurethane, latex and memory foam. Both latex and memory foam are referred to as “specialty foams”. Since there are many variations in processes and applications it is best to research these with the various manufacturers to understand what they use more completely.


Latex is rubber. In its purest form it comes from a rubber tree. There are 2 types of latex; NR or natural rubber and SBR (styrene butadiene rubber) or man-made latex. All latex is either a blend of the 2 or 100% natural latex. Blended latex is used to provide greater durability and more resistance to body impressions because of its better resilience. In compression tests some manufacturers claim that natural latex losses 5% to 10% more of its height in wear and tear testing. Natural latex is a natural substance and therefore better for allergy suffers, dust mite resistance, antimicrobial and does not contain chemical components like blended latex.

There are 2 processes used to make latex foam; Talalay and Dunlop. We recommend that you study more about these processes before buying a latex foam mattress. Talalay is generally more expensive and is represented as a premium version of latex but both processes have great comfort and support characteristics.

Talalay vs. Dunlop (regular latex): Reprinted from “Sleep like the dead” sleep products research site

Dunlop vs. Talalay – what are they and which is better according to actual owners?

Dunlop and Talalay are types of latex processing, not types of latex. The Dunlop process has been around for many decades, while the Talalay is newer. Both 100% natural latex and blended latex can be made using either process.

For the Talalay process, a tiny amount of latex is poured in the mold. Air is extracted to evenly distribute the foam liquid inside the mold which creates a consistent round, open cell structure. The mattress core is flash frozen to lock the cell structure in place and to prevent the particles from settling.

For the Dunlop process, the molds are fully filled, air is not extracted, and there is no flash freezing. In fact the Dunlop process uses the traditional method of vulcanization (heat) to cure the foam.

The result is that Talalay processed latex is more airy, less dense / firm and lighter (though still heavy) than Dunlop processed latex.

Another noteworthy difference is that the Dunlop method produces one piece of latex while the Talalay method produces latex in sections which then must be glued together.

Our data includes reviews from owners of both processing types. Based on this, owners as a group do not deem to find a noteworthy difference in overall comfort between the two. However, more owner data is needed to be certain.

In regard to durability / longetivity, many the mattress industry believe that Dunlop is at least slightly superior to Talalay, but our current owner data cannot confirm or contradict this claim.

Memory Foam

Memory foam was developed in 1966 under a contract by NASA’s Ames Research Center to improve the safety of aircraft cushions and later commercialized for mattress and pillow use. Memory foam is a polyurethane with additional chemicals increasing its viscosity and density. It is often referred to as visco-elastic polyurethane foam. Higher density memory foam softens in reaction to body heat, allowing it to mould quickly to a warm body in a few minutes. The composition makes it denser and heavier than other foams in general. Memory foam also has an open cellular structure resulting in greater “breathability” or allowing greater air flow.

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The Truth About Innerspring Mattresses

The Truth About Innerspring

Many retail sales associates like to talk about coil count. That can be very misleading and here are the reasons why:

What is coil count and what does it mean to the quality of a mattress?

This number should refer to the number of coils that the manufacturer of the springs puts into a full / double size innerspring. This is important to know because occasionally coil counts are referred to based on queen size innersprings making comparisons unequal. So always make sure that the coil count is based on a double size mattress. Certain coil designs lend themselves to higher coil counts than others. Normally continuous and pocketed coil designs have higher coil counts than Bonnell and Offset. Remember that by design higher coil count designs have thinner coil gauge steel.

Not all coil designs are the same.

There are several main designs. Just to name a few there are Bonnell coils, Marshall coils (also called pocketed coils), Continuous coils and Offset coils. Within each of those categories is a multitude of other categories for each. One is not necessarily better than the other so here are some questions you should ask your retail sales associate or investigate on line before buying an innerspring.

Pocketed Coil

The gauge of steel in the coils and border wire is an indication of quality.

This may be as important as the actual coil count. Steel gauge is measured in numbers like 12, 13, 13.5 but it is important to know that the lower the number the thicker the gauge of steel. A thicker gauge of wire is usually associated with greater firmness, durability and length of life. The border rod wire is normally a much thicker gauge and doesn’t vary as much. An 8 or 9 gauge is pretty standard for border rod wire. * Since steel is the main weight factor in an innerspring mattress a common sense approach to determining which product may have more steel in it is to lift one corner of the mattress to get a sense of how heavy it feels.

Bonnell Coil

What are innerspring coil “turns” and how do they affect quality?

The number of turns in a coil refers to the number of times the coil repeats its coiling pattern in the space between the top and bottom of the coil. A higher number of turns is associated with higher quality coil.

What does it mean when a coil is tempered?

It simply means that the steel has been stress relieved in the manufacturing process. This makes the coil resilient so that it can handle compression without damaging the steel in the coil. Most border rod wire is not tempered which is why you should never bend the mattress or it will take a set and not return to its original shape.

What is a special height or high profile unit?

These are innerspring units that have been stretched to give the innerspring a higher profile or taller appearance. This is done by the spring manufacturer and it usually does not add coil turns but simply stretches the turns that are normally specified in the unit.

What are the differences in the coil designs?

This is an excellent question to ask your retail sales associate. They should be able to give you a brief tutorial of whatever design is in each product. There are quality products that use each of the various coil designs but one design may have characteristics that favor benefits you are looking for. For instance if transference of partner motion disturbs your sleep the Pocketed coil is the design that will eliminate that problem because they are individually pocketed and there are no connecting helical wires to transfer motion.

Why are some innerspring coil counts unique?

These are what are called proprietary units and are only available to a specific manufacturer or retail customer. They are generally used so that these products do not have a direct competitive product comparison but that is not always the only reason.

Where do innerspring units come from?

There are a very small number of innerspring producers in the US and all manufacturers buy from them. There is at least one major mattress manufacturer that produces its own innerspring units. There are also many foreign sources for innersprings but they are not widely used because of restrictive tariffs that make them generally uncompetitive.

What type of steel goes into an innerspring?

The raw material used in manufacturing steel innersprings is called “rod”. This is a product made from recycled junk steel making innersprings a very eco friendly raw material.

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