Hi Fish17,
As you are aware, SleepEZ is a member of this site which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. They are extremely knowledgeable about latex and different configurations, and I wouldn’t hesitate to use their advice as a source of guidance.
As you’ve read, I would consider all latex (synthetic, blended or natural) to be very durable options to use in a mattress, and is not so much of a “good” or “better”, choice, but instead a personal preference as part of your personal value equation, as well as an issue of budget.
Usually, the “ultra soft” in Talalay would be considered in the 14-19 ILD range. It depends upon the term used by different manufacturers. Different manufacturers describe their latex to be more durable depending upon their blends and construction processes. Radium will generally state that their 100% NR Talalay is more durable than their blended, where Talalay Global has stated that their blended Talalay is more durable than their 100% natural. Again, these are all good quality products and you can get to a point of “splitting hairs” pretty quickly. I believe you may have read this from a previous post of mine: " In the lower talalay ILD’s … partly because of the difficulty of creating a homogenous mixture and partly because of the thinner cell walls … and because the lower ILD’s are usually used in the comfort layers which are subject to greater mechanical stress … then the shear forces inside the mattress and the higher elasticity of the NR (allowing the “thinner” material to stretch beyond its tensile limit) may work against it and it could break down faster than a blend. The testing of the producers of Talalay and the experience of many manufacturers seems to confirm this although Radium uses a different curing past in their all natural talalay and they have told me that their testing indicates that their 100% natural Talalay even in lower ILD’s has a similar durability to their blend."
This is a question that comes up once in a while so I think this is the perfect time to repost a bit of a synopsis I did for another forum member about quite a few of these differences. It’s more information than you probably want, but it might be useful for others reading this post. It can provide a bit of the “back story” of some of the recommendations that I provide.
Talalay in the same ILD as Dunlop will be less dense (will weigh less than Dunlop per cubic foot of material) because it has more air in it. This is the basis for the angel food cake vs the pound cake analogy.
Talalay is also more open celled than Dunlop and would be more breathable.
Resilience is a measure of how high a steel ball dropped on a material will bounce expressed as a percentage of its original height. It is somewhat opposite to hysteresis which is how much energy it absorbs (called hysteresis). Both Talalay and Dunlop are highly resilient but Talalay has greater resilience (a ball will bounce higher) and springs back more powerfully while Dunlop has less hysteresis (it absorbs less energy overall but it doesn’t decompress as strongly). The biggest difference between them is what is called compression modulus. This is a measure of how quickly a foam gets firmer as it is compressed more. ILD is generally (but not always) a measure of how much weight it takes to compress a foam by 25% of its thickness. At compression depths less than this Dunlop will be softer (compress more with the same weight) while at compression depths more than this Dunlop will be firmer (compress less with the same weight). They have a different response curve in other words and since Dunlop gets firmer faster than Talalay … even though the different response curves may cross at the 25% compression level … beyond this Dunlop will not compress as much as Talalay which is why it is generally considered more supportive or “firmer”. Another way to say this is that Dunlop starts off softer and then ends up (at compression levels more than 25%) firmer than Talalay.
This is also part of the reason that Talalay is considered to be more “springy” or “lively” than Dunlop because you will generally sink in deeper which means there is more up and down “movement” or “ride” with Talalay and it springs back more strongly and quickly. This creates a different “feel” between the two materials and is also why Talalay is often considered to be more pressure relieving than Dunlop because it allows for a deeper cradle in the same ILD … while Dunlop is considered to be more supportive because it doesn’t compress as deeply with greater weight … all else (including ILD) being equal of course. Some people will prefer the feel of one over another and because each has different firmness levels available … one is not “necessarily” better than another in either pressure relief or support layers if the right layering or ILD is chosen for each … but you may need to choose a softer ILD with Dunlop than with Talalay to get similar pressure relief in the comfort layers or a firmer Talalay vs Dunlop to get similar levels of support in the support layers. A “one step” difference in ILD which would be about 4 - 5 ILD would be “in the range” for most people where they felt similar.
This is an ongoing debate in the “latex community” about blended vs 100% natural Talalay and much of the information that is out there is based on promoting one over the other based on somewhat inaccurate information rather than recognizing the small differences between the two. these comments apply to Talalay and there are other factors involved in Dunlop.
SBR latex (synthetic) is a less dense material with a slightly different chemical structure than natural rubber. It is made from two chemicals which are Styrene and Butadiene while natural rubber is primarily Isoprene.
These two polymers (SBR and Isoprene) are similar but not the same. In addition to being primarily Isoprene … natural rubber also contains other compounds in varying amounts including proteins, resins, fatty acids, and sterols. These additional ingredients are missing from synthetic rubber (including synthetic Isoprene).
Natural rubber is more elastic, denser, and less consistent in its structure and particle size. It also softens as it ages (the crosslinks in its chemical structure break over time)
SBR rubber is less elastic, less dense, and more consistent in its particle size and structure. If becomes stiffer as it ages (the crosslinks in its chemical structure increase over time).
Natural rubber has particles of different sizes which tend to “agglomerate” (stick together) so it is thicker and more sticky than SBR which is thinner and has a more consistent particle size. This means that natural rubber is more difficult to work with and “gums up” the machinery more. NR is also more expensive than SBR. This means that natural rubber products including Talalay latex tend to be more expensive than synthetic or blended rubber products including Talalay.
Because natural rubber is a more dense material … it weighs more than SBR and would have a higher compression modulus (gets firmer faster) but because of its elasticity would also be a little more conforming.
NR resists impressions better than SBR but NR will tend to soften more than SBR (although there are other variables here which may affect this)
There are other differences between the two materials as well … some of which come from the different types of rubber itself and some which come from the additional ingredients that are mixed in with the natural rubber which alter how it acts … but these are the primary “practical” differences.
In practical terms all of these differences are relatively small in the cured foam and many people would not feel significant differences between the two in side by side testing. Natural would be slightly more “springy or buoyant” and more “supportive” while synthetic would generally feel a little softer and be slightly more pressure relieving (would allow for slightly more sinking in and cradling). The thicker the layers that are being compared the more it may be possible to feel a difference (for example someone may not feel the difference between two 3" layers of each material but they may feel a difference between 9" of each material).
In the higher ILD’s which use more rubber and less air … any differences in durability between them would be negligible. In the lower ILD’s which use less rubber … these differences may be more noticeable. Latex International acknowledges the differences between their natural and blended Talalay here while Radium has told me that they use a special curing past for their 100% natural in the lower ILD’s which should negate any differences in durability.
So the bottom line is Talalay made from natural rubber is more expensive, comes in a less specific range of ILD’s, is heavier, slightly more elastic and springy, has a higher compression modulus and more supportive, may get softer and develop impressions slightly faster in lower ILD’s, and is more natural. The primary reason that it was introduced (in 2005) is to cater to the “natural” market who are willing to pay more for a product which has has a more natural source even though it may not be as durable.
Both types are usually Oeko-Tex standard 100 certified in terms of harmful substances or VOC’s and offgassing.
ADMIN NOTE:Removed 404 page link | Archived Footprint: oeko-tex.com/media/downloads/Factsheet_OETS_100_EN.pdf
Those who value a more natural product for personal reasons and are willing to pay for it (in price and possibly lower durability), or who can feel a difference and prefer the feel that comes from the greater elasticity and compression modulus of the natural would likely choose the 100% natural Talalay.
Those who value the increased consistency, greater choice of softness/firmness levels, or lower cost of the blend or who can feel a difference in pressure relief, would likely choose the blend.
Both are great choices and in the end the choice between them is part of each person’s individual “value equation”
This is really a matter of personal preference and depends on which qualities are most important to you. You can read more about the different types of latex in this article and in post #6 here along with post #2 here but in essence the blended Talalay is more durable (especially in the softer layers) than the all natural, has a longer warranty, it is more pressure relieving (it is less dense than the all natural and allows for a slightly deeper cradle), and is less expensive than all natural Talalay, and has the same testing for safety in terms of harmful chemicals and offgassing of the finished product. On the other hand the 100% natural Talalay only uses latex raw materials that come from the rubber tree (natural rubber or NR) while the blended uses a blend of natural rubber and synthetic rubber (Styrene Butadiene or SBR which is synthesized mainly from petrochemical sources). In other words … it really depends on whether natural sources for their own sake is more important than the performance and value benefits of using the blended latex.
In your personal configuration, and using the theoretical information provided earlier, you certainly could choose the blended Talalay in the upper layers (perhaps confirming the brand of 100% NR being offered for the upper layer and potentially modifying that choice) and go with the Dunlop in the lower layer and end up with a product that would be extremely durable and also at a bit of a cost savings, as you mentioned.
I look forward to learning about what you decide to do.
Phoenix