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  • Handmade with love on the Swabian Alb
  • Custom-made products
  • Oeko-Tex certified products
  • 07382 23 20 10 (8 - 16 Uhr)
  • info@biona.de
What to consider when buying a mattress

What to consider when buying a mattress

In principle: Mattresses should support the regeneration of the body in connection with the suitable slatted frame. The spine should be able to take on the natural double-S shape and form a continuous straight line between head and coccyx. Especially for side sleepers, the shoulder and pelvis must be able to sink into the mattress so deeply that this straight line is created by itself.

Which degree of firmness is right for me?

Most mattresses are divided according to degree of firmness, mostly H2 and H3.

H1 is almost non-existent, as it is too soft to ensure good support for the back. H4 is for very firm mattresses, i.e. also for a high load.

However, the pure classification according to weight does not really do justice to people, because size and body shape should also be taken into account. If you choose your degree of firmness according to the international orthopedic guideline "the younger the firmer - the older the more comfortable", you are basically right.

The following also applies:

Weight < (body height - 80 cm) => H2 (max. 90 kg)

Weight ~ (height - 80 cm) => H3 (85 - 120 kg)

Weight >> (body height - 80 cm) => H4 (over 120 kg)

There are of course exceptions to every rule:

  • People with severe scoliosis should lie one degree softer.
  • People with very broad shoulders should also lie one degree of firmness softer so that the shoulder area can sink in far enough and the spine remains straight. In this case, a slatted frame with "middle zone reinforcement" would be good to adjust the hardness in the hip area.

What height should my mattress have?

The height of the mattress plays an important role. The higher it is, the more likely it is to avoid the compressions that occur when the mattress filling can no longer yield to the pressure of the body lying on it. A height of 16 cm or more is recommended.

Only babies or children should lie lower. Especially babies, so that they do not sink in too deeply and the airways are blocked. For a child mattress 12 cm is sufficient. For newborns in a cradle even 5 cm.

What is volume weight and what does it mean?

Volumetric weight is the term for the quality of foam in kilograms per cubic meter. The rule of thumb: the higher the density, the better the usage properties. Foam with a high density has high elasticity with low material fatigue.

The volume weight - abbreviated RG - thus indicates the density of the foam used for the core production of cold foam mattresses in kilograms per cubic meter [kg/m³] and thus determines the material usage.

Generally applies:

Cold foam mattresses with a high density are normally more elastic, more durable and more stable than cold foam mattresses with a low density. The lower the density of a cold foam mattress is, the worse and slower a cold foam mattress deformed by load reaches its original form again - in other words: the formation of hollows is promoted. The higher the value for the volumetric weight, the better the supporting force and the ability to stand upright again - and thus the support for the important changes of position during sleep - of the mattress.

The volume weight of cold foam mattresses is not directly related to their hardness. A hard cold foam mattress can therefore have a low density and vice versa. Thus, the apparent hardness of a cold foam mattress does not tell us anything about the quality! Degrees of hardness are determined by the compression hardness (see below) of the foam and the type of incisions.

In summary, the following applies:

A good cold foam mattress has a density of 37 - 50 kg/m³. A good, high-quality and durable cold foam mattress has a volume weight of approx. 50 - 75 kg/m³. For high-end cold foam mattresses, the density reaches a value of up to 85 kh/m³, which is somewhat exaggerated for normal-weight sleepers.

Is it possible to assign a density to a degree of hardness? What does this have to do with compression hardness?

Compression hardness and density (RG) are to be understood independently of each other. This means that two mattresses with the same density and the same core surface structuring can nevertheless have different "hardnesses" - this is also how the different degrees of hardness of mattresses come about.


Compression Hardness or Compression Hardness for foam (according to DIN 53577 or ISO 3386) is the physical force in Newton (N) acting on an area in square meters (m²), which is necessary to compress the foam by 40% of its normal height. The compression hardness is significantly influenced by the molecular structure of the cell walls.

The compression hardness therefore describes the force that opposes material to a pressure. Different compression hardnesses in cold foam mattresses are achieved by the different molecular structure of the cell webs.

The compression hardness therefore determines the degree of firmness or softness of a cold foam mattress.

How many zones are useful?

At least 5 zones make sense, 7 zones are optimal:

  1. Head zone
  2. shoulder zone
  3. lumbar zone
  4. Pool zone
  5. Thigh zone
  6. Lower leg zone
  7. Foot zone

Of course, the size of the person must be taken into account. Normally the lying zones are correct for an adult. But children under 1.55 m or adults over 2 m do not lie on the designated zones, which means that they can no longer serve their purpose. Here a mattress without zones of cold foam for children or one made of viscose foam for adults is the better choice.

Burls, waves or smooth surface?

It doesn't matter whether it has pimples, waves or a smooth surface. It is important that a surface structure is present, since foam, like water, has a surface tension. Without structure you would simply lie on top without really sinking in.

Yellow, green, blue or red?

You should not care at all what color the mattress is, because it has no influence on the material properties. In the past, colors were used to distinguish the different foams. In the TV and Internet age, where more and more purchase decisions are made based on beautiful pictures, color became a marketing tool.

Try to leave out the color when making a purchase decision, because, as I said, it says nothing about the quality of the mattress and you will not be able to see it later under the mattress cover and bedding anyway.

Incisions or gluing different foams together?

In principle, bondings are always barriers to air and moisture. Mixtures of different foams are normally not necessary, since corresponding properties can also be achieved with contour cuts. This is where marketing comes into play again. If the mattress is to be multicolored to look nicer, you have to glue. Often the same foam is then produced in different colors and glued together. This results in higher costs without increased benefits. On the contrary, now the mattress contains barriers of air and moisture.

If you still want a glued mattress, you should make sure that the mattress is not fully glued, but with stripes.

Of course, the exception is part of the rule:

  • Visco foam requires a carrier layer of standard or cold foam. Otherwise the visco foam would push through the slatted frame. Here you have to glue.
  • With "heavy load" a mattress made of only one foam would have to be at least 20 cm thick. Here then foams of different compression hardness are connected with one another to be able to maintain a common mattress height.