Was first developed by a US company for the NASA space programme in order to reduce the risk of pressure damage to astronauts from the tremendous ‘G’ forces experienced during take-off.

There are now many grades and densities of this type of material.

It is important to remember that a low density foam is much cheaper to produce e.g.. 30Kg per cubic metre.  Also, a lower density product has a shorter life when used in mattresses and overlays.

Some foams are particularly sensitive to cold, which is a disadvantage when going to bed in a colder room (which many individuals prefer) as the mattress will become very firm and take quite a while to become comfortable again… The bed can also seem much colder for a period.This can also be an issue with pillows, as you need an instant reaction from a pillow in order to support the head and neck immediately.

The top grade mattresses and overlays use an 80kg per cubic metre visco-elastic foam, and also provide 8cms of the foam as the sleep surface bonded onto a CMHR foam (combustion modified high-resilient foam).

It should be noted that any more thickness than 8cms of the memory foam is basically wasted, as there is no extra combination of support and pressure redistribution – equally any less thickness than 8cm will not provide the level of benefit required. Some short-term comfort will be evident on a thin foam overlay – but generally this type of product will only last a few months.

Odour – this is a common problem with memory foam, in that when the product is first unpacked some residue of odour may still be evident. Normally, any odour will dissipate in a few hours or max. over a week. Some inferior (and often expensive) products however, have a major ‘smell’ problem and customers are forced to return the products…

Some more closed-cell foams can cause the sleeper to ‘overheat’. This is a common problem experienced by many individuals. The fact that the sleeper will stay in one position for a longer period, allows for a build up of heat that needs to be dissipated through a more ‘open-cell’ foam. Therapura™  is an open-cell polymer, and rarely causes overheating.