Mattress Forum

Excellent info! Thanks.
So, if I can ask to help clarify:
For example, I once laid on some Dunlop latex and it seemed much more "dense" and others here in the past have noted that Dunlop latex tends to be denser, or feel denser, less spring-y, more of a "dead" feel as opposed to a bouncy feel. I know many including myself have had this impression and talked about it.

Are you saying this is just coincidence, that it depends on the maker, or batch, or something like that?
Or is our description "generally true" but not always true?
Or am I just plain wrong. (Nothing wrong with that, I'm willing to admit I might be wrong because I have very little experience with Dunlop latex.)

Your description is generally true but not always true.  I can think of a couple exceptions to the rule for sure. 

Thing is, there are many variables with latex much more so than Dunlop or Talalay process.  Especially since the words Talalay or Dunlop does not specify which material the latex is even made of. 

A list of the main variables in latex quality (not density):
1. What the latex is made of.
If the latex is all natural or even a partial blend the following will also play a role:
1. How much vulcanization and stabilization chemicals are used:
2.  How long the rubber is stored before being processed into a foam core.
3. Where the latex is grown (is it sourced from North Africa, or SE Asia, in particular your best latex comes from malaysia, but the rest of the good stuff from SE Asia)
4. What specific subspecies of tree the rubber is sourced from.
5. and finally the process will obviously matter, below I will explain why I list it so low on the hierarchy.

There are basically two substances that are considered latex.  Any plant milk which can be vulcanized into rubber, primarily the rubber tree would be the plant in question 99% of the time and 100% of the time with regards for latex in mattress use.  There is of course also synthetic rubber, made from petrochemicals it is called styrene butadiene.  You can make Dunlop or Talalay process rubber out of either 100% natural sourced latex or 100% petrochemicals.  With the same ILD rating, the performance of 100% synthetic vs 100% natural dunlop latex would be dramatically different.  You can also of course (and most commonly in North America) make latex using a blend of natural and synthetic rubber, typically 30% natural is the standard blend that latex international uses now-a-days and is the type of mixture you will see used in just about every mainstream companies beds.  They of course talk about the virtues of Talalay latex very commonly, which is the process they use for blended rubber. 

Interestingly enough even though you can make dunlop or talalay latex in any mixture of synthetic and natural rubber you can dream of you never see certain things too often.  primarily, you will almost NEVER see or find a manufacturer that uses Dunlop process for blended latex (synthetic and natural).  Most dunlop latex on the market will either be 100% synthetic (some cheaper Ikea mattresses) or 100% natural rubber (if you look at high end organic mattresses that use latex cores, usually dunlop is used all the way through or atleast the core).  Talalay process you will usually see made in synthetic blends, although sometimes 100% synthetic (like the stuff Sealy makes for themselves) or 100% naturally sourced Talalay, although more rare, latex international makes some like this but its not very common because it is not typically as pure of an end product as 100% natural dunlop rubber so you don't see too much of this being used in a lot of the most expensive beds around. 

Realistically most Dunlop latex is 100% natural and most talalay latex available is a blend, this is the main reason why you would typically be right in assuming dunlop will be denser and usually is.  Natural rubber is much heavier than styrene butadiene.  Of course don't take my last sentence to describe what dunlop or talalay IS, always make sure you know what the breakdown of materials is.  Chances are if you laid on a piece of dunlop latex that felt really dead it was either 100% synthetic or just an incredibly high ILD natural content. 

Anyway I am gonna tell you WHY Talalay is primarily used.  natural and synthetic latex have inherently different densities, when you mix the two of them together they cannot mix evenly, not to mention that vulcanizing agents will also have different densities.  Since most talalay latex here is made by latex international I will use them as an example.  Especially since the product is made in the US, but the rubber comes from North Africa.  When a rubber tree is damaged in the wild the milk of the tree would come to the surface area and form a giant rubber knot to fight off infection, this rubber will normally solidify within a matter of hours with exposure to air.  To prevent this from happening ammonia is added to the natural latex to prevent it from curing.  I personally am not privy to the exact details on how long the rubber sits around before being processed but since they send it by boat I think I am right to assume atleast a couple of weeks would go by if not longer.  Because the latex sits around for this long the appropriate amount of ammonia must be added, the more ammonia added the more vulcanization agents will need to be added to cure the end product.  So as time goes on you will always have a slightly less pure end product.  Once you have all these ingredients in a blend it is basically out of complete necessity that they must use the talalay process or there would be huge inconsistencies in the product.  On the flip side if one was using 100% synthetic or natural latex there really isn't much of a mixture at all in the first place and therefore no real need to even use the talalay process.  especially if the latex is processed close to the plantations as it will not be sitting around as long and very little extra chemicals will have to be added.  This is one of my biggest gripes with the industry constantly telling people Talalay is more consistent, obviously it is more consistent blend when you are using a blended latex, however it is actually the blending of latex in the first place from which almost all the inconsistencies are born from.

As far as what is bouncier, natural rubber is more elastic than synthetic rubber.  This is exactly why condoms and medical gloves still use natural latex because for safety reasons these things need to be able to stretch without breaking, synthetic rubber is far more brittle and actually more prone to cells being destroyed from compression and stretching due to a lack of elasticity.  This is also why density doesn't always mean a product is 'better' but the extra weight of natural latex is from proteins which make it more elastic, which is typically very desirable.  And would also mean the cores can conform more articulately with the shape of the human body.

I  could actually go into much greater detail but I am afraid I have a short story here no one will read anyway lol.  in closing though, you can compare Talalay to Dunlop in terms of ILD ratings quite fairly, however try to make sure you are comparing the same source material.  It wouldn't be fair to compare a synthetic blend talalay to an all natural dunlop, I would say this also works vice versa but as I mentioned no sane manufacturer would make a blended dunlop. 

Budgy, you are a font of information and I appreciate all the input you have given about latex!  I will also have to re-read it about 63 more times to totally absorb it, but will copy it over to a file so I can refer back to it in the future.  I know latex is an extremely long lasting foam, and now I understand why. 
I have not used it in my bed layering due to two reasons.  One, I had a latex bed once, mattress that was supposed to be 100% latex throughout(before I knew anything about ilds and such).  On the sales floor, it was dreamy.  At home, I didn't sleep all that well on it.  I sweated, my hubby sweated a LOT, it never gave me that aaaaahhhh feeling when I went to bed.  Then it developed a butt-dent, so I gave it away.  It was super duper heavy to move, but it was a CA king.   Later on, I bought a latex topper from a natural latex company but it was too boingy to sleep on for me...every time I turned around, I bounced and woke myself up!   Also seemed to sleep hot, under the thick mattress pad and sheet. 
Wish that there was a foam that was long lasting and not so bouncy and sweaty as latex. 
What is your company name?  There are some Canadian posters on here that might like to know where you are. 
Kait