Science of mattresses

This is the section where we take our mattress geek credentials to new levels. In your journey to finding the right mattress, the science of mattresses will be wheeled out to baffle, confuse and wear you into submission!

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If you’re desperate to get the basics then please read our top 5 tips, for the more scientific and fellow geek readership, please inspect our foam data sheets.  They tell you everything you need to know about the foams we use at John Ryan By Design.

Foam Data Sheets

At John Ryan By Design we provide you with all the information you need to make an informed mattress choice.  Below are the data sheets, for the ultimate mattress geek, for all of our foams.  If you want to you can now go to the furthest comparison possible, providing the other mattress manufacturers will let you see their data sheets, we bet our bottom dollar they won’t though!  That’s where we are different, nothing to hide and no secret formulas!

Density of foams

As a rule of thumb the higher the density, the firmer the foam.  There are some exceptions such as reflex foam but if you use this as a guide when looking at retailers foam mattresses it should help.  Beware, many retailers probably won’t know the density of the foams!

Foam GradeFoam TypeDensity Min KG/M3Density Max KG/M3Hardness Min (N)Hardness Max (N)
Vasco 40Vasco Memory Foam38424060
Vasco 60Vasco Memory Foam587270100
Laygel 60Laygel Hybrid Foam5763100150
Coolblue 70Coolblue Hybrid Foam657070100
Reflex 300Reflex Support Foam3032100130
Reflex 300FReflex Support Foam3032130160

Top 5 mattress science tips

1- Off-gassing may occur with a foam mattress and is almost non-existent with a 100% natural latex mattress. Off-gassing occurs around the home in a number of products, new paint, kitchen worktops, new car smells to name a few. It is when chemicals are released or omitted from the mattress as a bi-product via volatile organic compounds (VOC’s). The only way to reduce it to a minimum it is with a 100% natural latex. The longer the mattress stays rolled up the stronger the off-gassing will initially appear. All of our mattresses are made to order reducing the time they spend wrapped up.

2 – Foams are made up of a number of chemical components which all react and are then aerated to create foam. Some people show concern about the amount and type of chemicals used. Memory foam has however been around for 20 years without any significant issues. Obviously, there will always be those who are sensitive to certain chemicals. If you are concerned about the effect of these chemicals or your sensitivity the only way to reduce the effects again is 100% natural latex.

3 – Fire retardants (FR) are mandatory in the UK and are there to protect you the consumer from products that are likely to catch fire. Cheaper exports may not have the same or any FR compliance. All of our mattresses are fully complaint. In the case of 100% natural latex, a thin FR layer will be added either side to ensure compliance without detriment to the feel and comfort of the mattress.

4 – Dust mites occur wherever there is moisture, warmth and dead skin. Whilst Latex is naturally dust mite resistant, it is your bedding, bed wear and home environment that will almost certainly allow dust mites to exist. Apart from having an intensive cleaning regime we recommend you don’t pay over the odds for dust mite prevention features as its a losing battle!

5 – Comfort zones in memory foam mattresses should be avoided unless the manufacturer or retailer can show you exactly how these are constructed. Many will simply be ‘Frankenstein’ mattresses of different foams stuck together. If you really want a zoned mattress you are better off with a pocket sprung mattress. Zoning in foam mattresses fundamentally breaks the consistency of a foam mattress.


View Comments
  • Kats says:


    Found your website very informative – but I would like to ask which would be the best Memory Foam for me ?
    I’ve found MF to be very comfortable. Now though it doesn’t ‘remember’ -therefore doesn’t return to its original flat surface. I lay on my side – and all my weight is on that spot so when I get out of bed – the indentation remains there.
    I’m very overweight – 19 stone 7 lbs
    My height is 5 ft 3 ins
    Have lower back pain
    Arthritic hips
    Won’t go on ….. as the list of my ailments is never ending.

    Hi Kats, Given your weight the problem you will have is that most memory foam is only manufactured to a weight tolerance of 16-18 stone. Even then it is very soft and the life span of it is reduced significantly to say a 12 stone sleeper I’m afraid. Given the weight the foam will compress far quicker than normal and won’t return to its original shape. You will find this with nearly all foams once you reach 18 stone plus I’m afraid.

    I would only recommend 85kg memory foam which is rarely used in the UK mainly as its simply too firm for most people. We don’t use this foam for this reason.

    A better design would be to look at our new range of mattresses for heavier sleepers. We have designed these with both weight and comfort in mind as many retailers and bed sellers don’t stock mattresses that are both supportive and comfortable for this weight range. We think thats unfair so have designed some and are in the process of testing the prototypes with customers as a final seal of approval. For these models I’ve used a mix of high density foam layers for the support and then hybrid foams or latex for the topper layer which is the comfort layer of the mattress. These mattresses are completely turnable and have removable turnable toppers which can be replaced if they become compressed, like your current memory foam, rather than the entire mattress.

    If you’re interested please get in touch as we are offering these prototype models at a significant reduction. All we ask is your feedback once you’ve had it a few weeks. We do offer the love it or return it guarantee on them providing they are standard sizes. If you want to discuss further please give us a call Kats. Lee

  • Jaz says:

    Thanks guys.
    I’m buying a memory foam mattress with an overall thickness of 20cm.
    With 2cm of ‘soft’ 45kg density memory foam, on top of 8cm of high density 75kg memory foam. With a base of 10cm reflex foam.. Will also have a removable Outlast cover. It was voted a Which? ‘Best Buy’ a few years ago, for whatever that’s worth..
    Really excited about getting it!
    Your guides have been really helpful. So Thankyou for that..

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