Mattress Construction

Discussions General Mattresses Questions
1

Hello from the U.K. First of all can I congratulate you on such a well informed site:)
Initially I was going to construct my own latex mattress but unfortunately in the UK it is proving difficult apart from one supplier to source Latex slabs so could build my own, and it is near impossible to source a suitable ticking without having one custom made which would be very expensive. The only thing I can get is more of a encasement/protector.
With this in mind ive decided to have the lower layers in foam and a Latex comfort layer on top and would appreciate your Knowledge on the following please.

Option 1
1/ Support layer 8" HD foam
2/ Middle layer 3" convoluted LayGel (artificial latex) 60kg density, min(N) max(N) hardness is 100N to 150N = 22-33 ILD
3/ Top layer 31/4" 85% natural Dunlop Latex 65kg density, 4.8Kpa = 35 ILD

Option 2
1/ Support layer 6" HD foam
2/ 31/4" 85% natural Dunlop Latex 65kg, 35 ILD
3/ 31/4" 85% Natural Dunlop Latex 65kg, 35 ILD
I am also considering adding a 3Lbs merino wool pad on the top of each option above if this makes sense
I am165Ibs and my partner 140Ibs both under 72" tall, side sleepers if this helps
Could you please tell me how the above options would feel when we lay on them as we would like a medium mattress but feeling soft on the comfort layer and supportive.
Ideally I would like an all natural latex mattress but the cost involved in the UK for Dunlop Latex alone never mind in Talalay especially if custom built , I think this would be a lot more expensive than you guys pay in the USA. Especially as we want a high mattress at least 12" thick, or even if was practical to have a 12" mattress in U.K king size 79"x59" approx

Any help would be much appreciated
Thanks Kez

2

Hi kezwald,

Welcome to the Mattress Forum! :slight_smile:

As you’re aware, this site focuses upon North America, so I’m sorry I can’t be of much help with souring materials in the UK. But I can comment upon some of your DIY questions.

The first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).

As for your configurations, the kPa and ILD numbers for the density of Dunlop latex you are providing don’t seem to align too well, unless these numbers were achieved at a deeper 40% or even 60% deflection (versus the “usual” 25% deflection) using ISO 2439. Density is the best way to relate softness and one piece of latex to another in Dunlop latex, and most manufacturers would consider a 65 kg/M3 Dunlop latex to be in the “soft” range. The ILD and kPA you show is that of a firmer piece of latex. A kPa of 4.5 or so is generally consider to be firm for Dunlop, as would a 35 ILD. So the first thing I would mention is that you are considering using some pieces of “softer” Dunlop latex in your proposed construction.

Next, I would tell you to find out the actual density of the polyfoam cores you are considering using. The term “HD” for polyfoam is overused for a very wide level of foam densities, so you’d want to be given a number instead of a term for this foam. I’d recommend at least 1.8 lb/ft3 density.

As for how this would feel, that is the one thing that I wouldn’t be able to relate to you, as there are far too many personal variables and preferences involved, and unless you are replicating a mattress that you have already sampled in person, the only true way to tell how something like this would feel would be through your own personal testing.

Assuming the polyfoam core was at least a 1.8 lb density, the materials you are considering using certainly would be of a better and more durable quality range, and I would think that your resulting mattress would be in the “soft to medium” range, but that again is entirely subjective.

All of this is part of the DIY process, and if you aren’t able to copy a similar design that you’ve already sampled, then your best option is to acquire the guidance of a foam supplier or manufacturer who has experience with the type of componentry you are considering using.

Best of luck, and I’ll be interested in learning about what you decide to choose, or if you have more specific questions.

Phoenix

3

Thank you for your informative reply and sorry for the late response.

Further to your questioning regarding 4.8Kpa to ILD not matching up to the 65KG/m3 I have found this information.

The hardness of a foam is a measurement that gives a perceived firmness rating for a customer, ie the harder the foam is the firmer it will feel. This is where density being the only measure of support is inaccurate. You need to also know the hardness. Hardness is measured in a set range of tolerance and is not a one size fits all figure. It is worked out by compressing a piece of foam to 40% of its original size. This measurement is then displayed in newtons (N) so a hardness rating of 70-100N means it takes between 70 and 100 newtons of pressure to compress it to 40%. The higher the figure the more force is needed and, therefore, the firmer the foam.

so what 65KG/m3, 4.8Kpa means in true ILD figures at 20% compression I don’t know, giving my calculation of 1Kpa=7.25ILD initially ? I would be grateful if you had any input on this.

Other than that I have decided against the man made foam roures given the when priced up there was not a huge difference in cost going for 100% Dunlop. which I’m looking at a company know for a price and spec which I will further share with you.

Than you
Kez

4

Hi kezwald,

The best article I’ve found that states the relationship between Pascal, Newton and softness, without getting “too deep into the weeds”, is this one from European Bedding. I think this has some really good information for you.

Regarding the kPa, there are still variables we don’t know, even the size of the disc being used for testing, and in the end it’s really much easier and more relative to use the density of the Dunlop latex to related the softness. You can see some of the ILD’s for different densities of Latex Green’s 100% natural Dunlop in post #2 here. 65 kg/M3 is generally regarded as a plush Dunlop latex.

Phoenix