05.It's what's inside that counts
You can’t tell much about the quality of a mattress by looking at it from the outside — you’ll have to rely on knowledgeable and helpful salespeople and cutaway models in stores. (If you don’t find either of these, go elsewhere.) However, it helps to know something about the structure of a mattress before you go shopping so you know what to look for, what to ask, and how to understand the answers.
The spring unit is the main source of support for your body. Five factors can influence the degree of comfort, support and durability of a mattress: the number of springs or coils, their shape, the gauge of wire used, the number of turns in each spring and the distribution of the springs.
The final effect will depend on an interplay of all these factors. So, for instance, more springs aren’t necessarily better if they’re lower in quality. Let comfort, rather than stats, be the deciding factor.
The number of springs: There should be at least 300 coils in a double bed, 375 in a queen-size and 450 in a king-size. But otherwise, more doesn't necessarily mean better - let comfort be your guide.
Spring shape: There are several shapes of spring, and it may be a good idea to try lying on the different kinds, as one type may suit you better.
Wire gauge: Not all springing systems are made from wire with the same strength, durability and quality. Ask for information about the gauge of wire used in a mattress. The lower the number, the more durable the wire (that is, 13-gauge wire is thicker and stronger than 16-gauge). Wire may also be measured in millimetres — obviously the higher the number the thicker it is.
Active turns: A further variation is the number of active turns in the spring or coil — that is, the number of turns that are absorbing and supporting the weight of the body. The more turns, the softer the bed and the longer the springs will last because the work is spread around.
Distribution of springs: Some beds differentiate support zones in the mattress, usually putting firmer springs in the centre third of the bed to support your heavy bits. It’s difficult to confirm whether they really add to the quality of support offered by the mattress.
Hourglass-shaped springs are used in the original inner-spring system, called the Bonnell System. They’re joined together with spiral wires to form the unit. They compress quite easily at first, but then get firmer the more they’re compressed (hence offering more support), resulting in a ‘soft but firm’ bed. They tend to be found in cheaper mattresses.
Continuous coil springing is made from a single length of wire shaped into a system of coils. It means manufacturers can increase the density of coils, which they claim gives greater support and minimises partner disturbance. The number of springs or coils is irrelevant in a continuous system.
Open-ended coils are joined together to form a spring system, but the top (and bottom, for a double-sided mattress) of each coil is free to move independently. This allows each coil to adjust to the weight on it, with the free-moving bit compressing relatively easily for comfort, and the body of the coil offering more resistance and therefore firmer support. Because there’s more turns -- and therefore wire -- in these springs, they tend to be more expensive than Bonnell or continuous coil systems
Pocket-spring mattresses consist of a grid of springs, each in their own fabric pocket. Because they’re not wired together, each spring is able to work more or less independently — the weight on one spring doesn’t affect those surrounding it (except for pull by the mattress cover). Tests by our German counterparts consistently rate pocket-spring mattresses the most comfortable type of inner-spring mattress.
Hourglass-shaped Bonnell springs (left) and continuous coils (right) are joined at the top and bottom to form a single spring unit, while pocket springs are able to move more or less independently (though the mattress coverings limit complete independence). Open-ended coils are joined together part-way down the spring, rather than at the top (which is free). The most comfortable spring system comes down to personal preference and depends, among other things, on your size and weight, and whether you sleep alone or with a partner.
Some also include side or edge support springs, which provide more strength and support at the edge of the mattress, and protect against the spring and comfort systems breaking down around the edge of the bed (which is thought to be a major cause of mattress failure).
Padding and ticking
The comfort layer is what lies between you and the springs — it determines how hard or soft the mattress feels against your body.
A manufacturer that makes a large range of mattresses will often use the same spring unit but vary the fillings — the more expensive the mattress, the better the filling. And the better the filling, the longer the mattress should last.
At the top end of the market (over $2500) fillings include silk, wool, cashmere, premium foams, latex and goosedown. At the lower end (under $700), materials include lower grades of foam, reclaimed cotton fibres and coconut fibre. These don’t tend to last as long because they break apart more easily, forming lumps and pockets, and lose their ability to spring back more quickly. A $7000 bed won’t last seven times as long as a $1000 one, however — you’re paying the price for luxury rather than durability.
You might want to think twice about getting a ‘pillow top’ mattress (where a separate thick layer of padding is attached to the top and bottom of the mattress). They tend to lose their ability to bounce back over time. We've had complaints from consumers to this effect, and the mattresses are very expensive. If you want extra cushioning, buy a separate padded overlay made from foam, feathers, cotton, latex or memory foam, and replace it when needed.
The way in which the padding is secured in place can also influence how well the bed maintains its comfort. In top-of-the-range mattresses, each layer is handstitched into place to prevent the materials shifting around. This is a specialist craft (called hand-tufting) and can take one person several days. Retailers should know which mattresses are hand-tufted — they’ll be the expensive ones.
As far as the outer cover (or ticking) goes, cheaper, less durable mattresses will probably have a flat cotton cover, while more expensive ones have quilted damask covers (linen, silk, cotton or wool fabric woven with patterns) - which will get covered up with a sheet!
A typical ‘ensemble’ consists of a box base and inner-spring mattress. Some box bases are simply that: a wooden box with a board or slats across the top, covered with fabric to match the mattress. Others have internal springs, which take some of the load from the mattress, helping to extend its life. When you’re thinking about a new mattress, take a good look at the condition of your base — if it’s sagging or worn you may need to replace it too, as it won’t support your new mattress properly and will shorten its life. Some companies won't honour warranties if you've used the mattress on a base they consider inadequate.
There are two types: fixed and flexible slats. Flexible slats are attached to the frame with pivoting holders and allow some give. Fixed slats — the more common of the two — attach straight to the frame and offer little to the mattress. Latex and foam mattresses work best on a flexible slat base; fixed slats are fine for inner-spring mattresses.
Despite what you may see or read, one major manufacturer tells us there’s no such thing as a mattress that shouldn’t go on a slatted base. A mattress may last longer on a sprung base, but a slatted-base bedstead itself could last a lifetime (unlike a sprung base).
Make sure the slats aren’t too far apart — about 5 cm is good.