Mattress talk, Glossary, Guide

As with most industries, the deeper you dive into the world of mattresses, the deeper it can become. We’ll take you through a  few numerous terms, so that you can be clued up when making a mattress buying decision and show off to your mattress salesperson with your knowledge. 

• Off-gassing
•  Tog-rating
•  Motion transfer
• Zoned-construction support
•  Indention Force Deflection

Zoned-construction

This is when different levels of firmness, support, or even completely different materials are used in different parts of the same layer of a mattress. They are often used to provide additional relief in areas where pressure is more prominent, such as the pelvic area and shoulders.  

There are varying zoning schemes that mattresses utilize. The most common form of zoned construction is in the three-zone mattresses which place a firmer zone under the lumbar, or lower back region for sturdy support there and softer zones for the lower body and upper body above the lumbar region. Two-zoned construction is less common in the mattress-making industry. It is simply comprised of two zones; the firmer zone starting from the lower part of the ribcage down and the softer zone being placed under the top part of the body. This technique does not offer lumbar support and often compromises spinal alignment since the upper body will usually sink lower than the pelvic area, instead favoring alignment of the upper back, shoulders and neck. As can be seen, zoned construction is not easy to pull off and can bring more harm than help if not implemented properly, so companies such as Emma  have carefully thought out and designed their mattresses with a zoned construction that optimizes its beneficial usage. You can see this type of construction in effect with Emma mattresses on the right.

Emma Original Mattress

The verdict

The Emma original mattress is one of the best mattresses  out there based on sales-figures despite only being around since 2015. There are numerous aspects to the Emma original which makes it incredibly popular. The breathability of the Airgocell layer provies an effective cooling mechanism and prevents you from being disturbed by night-time sweating. The memory foam in the Emma original is extremely adaptable and ensures that the mattress moulds to the shape of your body, so your comfort is virtually optimised. Though the Emma original may not be the best mattress  in terms of edge-support it seems to deliver in most other areas, bringing you comfort, coolness and solid support which is mainly attributable to the underlying base. This product review shows that  there is the chance that it is the  best mattress for you

Our grading of the Emma Original Mattress

Emma Original Mattress: The classic Mattress, a bestseller throughout Europe

4.5 / 5

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Indention force deflection and Compression modulus

This is often referred to with the acronym of IFD or even ILD which stands for Indention Load Deflection. Used sometimes interchangeably, they refer to the measurement of a mattresses’ deflection of a pressing load. They are typically used as a gauge for the foam of a mattress and essentially measure the firmness of the foam. Specifically, ILD is the number of pounds it takes for an area of foam to compress by 25% of its original state.
 The higher the ILD, the firmer the foam. To give you an idea of the IFD scale, the IFD of a car seat is usually between 40 and 50. An ILD of between 10 to 16 is generally accepted as the bracket you would want your mattress’ memory foam IFD to fall into. From 10-12 is quite soft and will have a bit of sinkage. From 12-14 is the medium level of firmness, whilst 16 and above is quite hard. The testing standard for the ILDs of polyurethane foam which is almost universally accepted is ASTM D3574. 
The ratio of an exerted pressure to the resulting strain of the material subject to the force is called the Compression Modulus. This isn’t used very often, though. It is another measurement of foam response to subjected pressure and is similar to ILD, but instead of measuring firmness, it measures the stiffness because the ‘Strain’ is the compressed length divided by the original length, which gives an idea of how a force changes the shape of a material when compressed. 

Motion isolation 

This term describes whether or not the movement of a person or testing object has an effect on another part of a mattress. This can be considered an important piece of information for couples who may have a restless sleeping partner who moves a lot. A common test for this term is leaving a glass of water on one side of a mattress, whilst causing disruption on the other side. If the water in the glass doesn’t experience much motion or doesn’t allow any water to escape, this could be a reliable indication that the motion isolation of a mattress is high. When you sleep on a mattress with decent motion isolation then you can expect not to be disturbed by any movement from the other side of the mattress. 

Motion isolation performance for different types of mattresses

Tog-rating

This is the unit of measurement that calculates the thermal insulation of a material. It is used in the mattress industry often to assess or describe how warm a duvet, pillow, blanket, or other material that compliments the function of the mattress. TOG is an acronym for ‘Thermal Overall Grade'. The scale ranges from 2.5 at the cool end to 15 which is the warmest. It is recommended that duvets not exceed 7 if they are for the summer and not fall below 10.5 if only for the winter. Duvets filled with duck or goose down usually have quite a higher TOG rating than synthetic or feather fillings because of the thermal retention of down fillings. 

It is generally advised that children not be left to sleep in duvets with a TOG rating of over 10.5 because as they typically have smaller bodies, they will trap more around them and this will cause more trapped heat. This means the actual warmth will be higher than the tested TOG rating of the duvet. 

Off-gassing

This is the process of a material releasing vaporous chemicals into the air. With mattresses, off-gassing usually occurs when they are recently unpacked and opened. What is released specifically released are VOCs which stand for Volatile organic compounds. They are byproducts of the synthetic manufacturing process of a foam or polyfoam mattress, therefore are man-made. Though the smell they produce can be unpleasant it is not harmful, since it is commonly agreed by the experts, that the emissions of VOCs are well below the threshold at which they could become toxic for people. 

VOCs are particularly more apparent with the in-a-box mattresses because they use vacuum sealing to compress the mattress into a tight space which locks the VOCs inside which burst out when unpacked. VOCs are further sub-divided into three categories based on the ease with which they are emitted and they correspond to their boiling points. Very Volatile Organic Compounds or VVOCs have low boiling points and are more likely than the other types to be released from the mattress into the air. Volatile Organic Compounds are in the middle ground and Semi-Volatile Organic Compounds which have high boiling points are less likely to be found in the air than the other forms. 

Latex mattresses don’t usually contain a high potential for off-gassing because usually natural latex is used and excludes synthetic materials. Innerspring mattresses also tend to not use any synthetic materials with VOCs, so they also usually are not going to produce off-gassing and if it does the space that usually exists between the coils of an innerspring will allow the emission to dissipate very quickly instead.