Hi,
I recently got more information from a seller that I am about to buy a latex mattress from, and I found something really strange, at least in the way I understood things. I was told that those numbers:
For a 20%natural/80% synthetic latex, with 60 density, the firmness in kilopascals is 4,9 ~35 ILD
For a 85%natural/15% synthetic latex, with 75 density, the firmness in kilopascals is 3,7 ~26 ILD
For a 85%natural/15% synthetic latex, with 80 density, the firmness in kilopascals is 4,6 ~33 ILD
considering the fact that 26 ILD is quite soft, and the medium value is 35 ILD, means that there is a huge variance in ILD if you would compare a fully synthetic latex mattress of a given density to a mattress that has the exact same density but fully natural.
The way I see things, if for 85% natural blended with 15% synthetic latex has a variance of 7 ILD between 75 and 80 density, then what about full natural latex with 65 density? Is it something like 10 ILD?
What am I missing here? Is it something wrong in the numbers?
Is it that every 100% pure natural latex out there in the world that has a lower than 75 density is soft?(or something like that).
Please help me understand what I am missing here, please tell me a way I can make sure that I am buying the correct firmness based on the data I have.
I tested a firmness of 4,8 kpa and is perfect for me, yet I am not sure that the 85%natural/15% synthetic latex, with 80 density can really have 4,6 kpa ~33 ILD, as this would be a compromise I would agree to make. Or shouldnât I?
Natural rubber (NR) is heavier than synthetic, therefore all else being equal:
Latex with a greater percentage of NR will have a greater density. (The density measurements youâve indicated are in kg/m3). This is probably enough to explain the confusion youâre describing.
Density is usually a measurement for dunlop latex, which Phoenix says is often not measured for ILD. Youâre assuming that the measures of density, ild, and kpa have been independently and accurately measured. Itâs entirely possible a target density is established, and other measurements estimated based on that.
For example, to totally confuse things, I have 2 layers of 100% NR Dunlop. They were described as 55kg/m3 and 65kg/m3. I actually weighed them, and I came up with 70kg/m3 and 80kg/m3 as actual measured density, causing something of a mystery in its own right. The point is, the measurement of firmness, density, etc., is hardly a science with narrow tolerances. Talalay ILD by contrast, from latex international or radium, seems more consistenly measured.
NR behaves different than synthetic (they are different materials after all). Iâve heard people say NR is more elastic and conforming, therefore:
I donât believe you can compare the two to accurately predict what a different piece of latex with a totally different ratio of NR to synthetic would be.
I donât specifically know about the kilopascals measurement.
Most 100% NR dunlop Iâve seen, once you get <75kg/m3, the word âsoftâ is often beginning to be used. But, itâs by no means a scientific measurement. Iâm accustomed to seeing 100% NR Dunlop latex at:
55kg/m3 = really soft, harder to find, many have commented on potential durability problems
65kg/m3 = soft, some say possibility of durability problems
75kg/m3 = medium-soft to medium
85kg/m3 = medium to firm
95kg/m3 and above = firm and firmer
Latex Green advertises a +/- of 5 kg/m3 so itâs hardly scientific
Also, as I mentioned, thatâs assuming itâs accurate in the first place anyhow.
Other factors yet, such as production method (talalay, dunlop- both mold and continuous pour), differences between vendors, and firmness inconsistencies within latex foam (more prominent in dunlop) will also contribute to variation of firmness to density or other comparisons.
Only your own testing and perceived feel will be for sure
I think dn covered everything at least as well as I could and the only thing I could add is post #2 here which has a list of some of the density/ILD ratings for Latex Green 100% natural Dunlop as a reference.
There is also a pressure converter here which can help you convert one type of pressure measurement to another. I would also keep in mind that firmness/softness ratings can also vary by the type of units they use, the percentage of compression they use for testing (some use 40% compression and some use 25% compression), and the thickness of the layer that is being tested (the two most common are 4" for polyfoam and 6" for latex) so âapples to applesâ comparisons can be difficult.
