Latex rubber is made of a milky liquid (not the sap) which comes from a rubber tree. This kind of latex is known as NR that stands for Natural Rubber. It can also be produced synthetically from a compound named SBR (Styrene Butadiene). While the true latex molecule in both resembles natural latex has a more intricate chemistry and much more of the desirable qualities which make latex appealing in mattresses (elasticity, durability, compression modulus, resilience, and others). SBR is also less costly than natural rubber (NR).
The first is named Dunlop which produces a milder form of latex. This system is more common around the world because it’s a simpler less expensive way of manufacture. When used by a respectable manufacturer, it produces an extremely large quality latex that is quite compact and very elastic. Because in this way of manufacturing a number of the latex particles “settle” while it’s being made, Dunlop is somewhat less consistent in softness over the whole surface of the coating. It’s also more challenging to create Dunlop in a milder version and it’s seldom seen in ILD’s (a measure of softness) under the mid 20’s (medium soft). This gives it a very substantial support variable (progressive compression) that is a desirable quality in a service material.
Talalay on the other hand is made with a vacuum system that requires less raw material in its manufacture and ends in a foam and mobile structure which is more consistent than Dunlop, has a lower density (weight) in equal levels of softness/firmness, and can be created in softer versions than Dunlop. In its firmer versions it may also be a very desirable material in service layers also.
The softness or hardness of latex may also be varied by altering the quantity of raw material used in the center (in the case of Talalay), changing the size, shape and pattern of these pincore holes in the latex, altering the compounding formula used, or by changing the amount of air in the foam and the dimensions of these cells during foaming. The holes or “pin cores” are employed in manufacturing both kinds of latex to apply heat to the interior of the latex from the mould to make it set or cure after it’s foamed. While the holes are a essential part of manufacturing, the ability to modify the softness or qualities of the latex being made by changing their size and shape is a welcome side effect. Due to its thicker denser character and its high service variable, Dunlop latex is a favorite and an excellent choice for a support center material and less popular as a comfortable coating material however it can be used quite efficiently in both and this is truly a preference issue.