Cool Blue Review
Cool blue is a description of foam colour that has become a product category. The gel particles are real and the effect stops mattering once the heat has nowhere left to go.
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Verdict
Cool blue is a description of foam colour that has become a product category. The blue gel particles are real, they conduct heat marginally better than untreated foam, and the effect stops mattering once the heat has nowhere left to go. Which, in an all-foam mattress, is after about twenty minutes.
Buy it if
You want a cheap foam mattress and you are not relying on the cooling claim.
Avoid it if
Heat is the problem you are trying to solve. This is the wrong construction for that entirely.
See the current Cool Blue offer
Cool Blue is a foam type sold by many manufacturers rather than a single brand.
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Cool Blue on Amazon UK
Widely listed under many seller names. Compare the specification, not the colour.
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| Specification | Detail |
|---|---|
| Type | Gel-infused memory foam |
| What the blue is | Gel particles and dye |
| Sold by | Many manufacturers. Not a single brand. |
| Cooling mechanism | Conduction at the surface, not airflow |
| Foam density | Almost never published |
The scores
An ordinary budget foam mattress with a colour that has become a marketing category.
Cheap, and so is every all-foam mattress at this level.
Budget foam with no spring core and no published density.
The whole selling point, and the weakest score. Gel moves heat a few centimetres into foam and leaves it there.
No perimeter reinforcement.
Foam does this well. It is the genuine strength.
Varies enormously by seller. Check carefully.
What the blue actually is
Gel-infused memory foam contains gel particles mixed into the polyurethane. Gel conducts heat better than foam, so at the moment of contact it draws warmth from your skin faster than untreated foam would. That produces the cool-to-the-touch sensation, and it is real.
The blue colour is dye. It signals the gel is there and does nothing itself.
Here is where it falls down. Conducting heat away from your skin only helps if the heat then has somewhere to go. In an all-foam mattress it does not: it moves a few centimetres into the foam and stays there, because foam has small closed cells and almost no air movement through it.
So the surface is cool when you lie down, warms as the foam beneath it saturates, and by the middle of the night you are on a warm foam mattress. This is why people who buy gel foam specifically to solve overheating are so often disappointed.
What actually removes heat from a mattress
Airflow, not conduction
Heat leaves a mattress when air moves through it. That requires open structure.
- A deep pocket spring layer. Air moves through the gaps between springs. Otty's 16 centimetre spring core is the clearest example at a sensible price.
- An open grid. Purple's comfort layer is mostly empty space, which is why it earns the only 10 out of 10 for temperature on this site.
- Natural fibres. Wool and lyocell manage moisture, and the sensation people call sleeping hot is usually clamminess rather than temperature.
A cover treatment, a gel infusion or a colour changes how the first fifteen minutes feel. Structure changes the whole night.
The number that is never printed
Since cool blue foam is sold by many manufacturers at many prices, the way to compare them is foam density, and essentially nobody publishes it.
Density is measured in kilograms per cubic metre. Standard memory foam runs from around 16 to 80, with decent comfort layers between 48 and 72. It is the best available predictor of how long a foam mattress holds its shape, because low density foam develops body impressions within three to five years and high density foam holds considerably longer.
Foam cost is dominated by density, which is exactly why brands competing on price stay quiet about it. At the cheap end, silence is informative rather than neutral.
A correction worth making
Commonly repeated, and wrong
Gel-infused and cool blue foams are sold as cooling mattresses, and they change how the surface feels on contact rather than how the mattress behaves through the night. Gel conducts heat away from the skin faster than plain foam, but in an all-foam mattress that heat travels a few centimetres and stops, because foam has small closed cells and almost no airflow. Only an open structure, a spring layer or an open grid, actually removes heat from a mattress.
Should you buy it?
Only as a cheap foam mattress judged on its own terms, for a spare room or a tight budget, and not because of the cooling claim.
If heat is genuinely your problem, buy structure rather than chemistry. Otty's Original at around £500 has a 16 centimetre spring layer, and Purple's grid is mostly open space.
Questions people ask
Does cool blue memory foam keep you cool?
At the surface, briefly. Gel conducts heat away from your skin faster than plain foam, which is real. In an all-foam mattress that heat travels a few centimetres and stops, because foam has small closed cells and almost no airflow. By mid-night you are on a warm foam mattress.
What actually removes heat from a mattress?
Airflow through an open structure. A deep pocket spring layer, where air moves through the gaps between springs, or an open grid. Cover treatments, gel infusions and colours change how the first fifteen minutes feel; structure changes the whole night.
What is the blue in cool blue foam?
Gel particles and dye. The gel conducts heat marginally better than untreated foam. The colour signals the gel is there and does nothing itself.