Natural Latex Rubber
Botanical latex foam rubber is the most durable mattress material available. It is completely renewable, sustainable, nontoxic, hypoallergenic, temperature regulating and is terrific for pressure point relief. It can be processed a couple of ways.
It is unfortunate that many stores represent blended latex often called “natural latex” as the same product. Regardless of the content, there are three main processes used in mattresses. All of these processes can be 100% Botanical, 100% Synthetic, or blends of the two.
(1) Dunlop, which has been around for over 80 years, lasts 2030 years on average provided it is 28 ILD or more. It is vulcanized in a glorified waffle iron, once latex has been whipped in an ammonia based soap. This rudimentary process when executed properly is the most consistent mattress over time.
(2) Talalay, a newer method for making latex foam. This is done by putting the whipped latex and ammonia soap in a vacuum sealed mold and filling it up part way. Once this is done, they seal the mold, and vacuum out the excess air. This causes the latex to expand and filled to void. Then the latex is flash frozen with CO2 and vulcanized. This process creates a more even distribution of air bubbles than dunlop and is more consistent on the microscopic level.
In practice you will not be able to feel a difference and it will have a significant impact on the durability of the mattress. Talalay latex is often used as a selling feature over dunlop latex. However, talalay will soften more quickly over time as a result of using less raw material to get the same feel.
(3) Continuous Pour, is often used in the quilt of mattresses. It is usually produce in thin layers at light densities. This is done by extruding the whipped latex in sheets onto a conveyor belt, then vulcanized washed and rolled. When produced it will have no holes like the other processes. In order to make it look different than poly foams, holes are often punched in it to make it look like other latex foam.
Washing and Drying
Once the latex is vulcanized, the foam can be washed to eliminate the ammonia based soap residue, and the protein from the sap of the rubber tree (if it is botanical latex). This should be done 5 times to do a complete job. Not all manufacturers do this. If it is not done, the latex will have a fishy? smell. After the washing is done the latex should be kiln dried to eliminate moisture and prevent molding on the inside of foam. Improperly dried latex will lead to mold issues with poor quality latex; this would appear on the underside of a mattress in the middle.
Natural Latex (Botanical Latex)
Natural latex is the milk of the rubber tree. Rubber trees grow within about 10 degrees of the equator and constitute some of the best managed forest systems in the world. Therefore, natural latex is very eco-friendly. The foam made from these trees is not subject to the body impression issues that you find in polyurethane, memory foams, or the synthetic latex. It can also be certified organic. Organic latex comes from the same forests as natural latex, but someone has gone to the trouble of paying for a certification. The forests are the same.
Synthetic latex is an attempt to recreate the benefits of natural foam by combining 4 laboratory chemicals. This is a lower cost alternative to natural latex; raw natural rubber is more expensive. However, synthetic latex is not as durable as natural latex. It develops sags, much like polyurethane foam, and is not a renewable resource. It is not a “green” material, but it doesn’t off gas or have an odor. It is also nontoxic.
Blended Latex (often called Natural)
Blended latex, is less expensive than natural, and more expensive than, all synthetic rubber. Similarly, it is more durable than the all synthetic and less than the all natural. It comes in varying compositions ranging from as little as 3% synthetic, all the way to 100% synthetic. Anything more than 70% synthetic latex should be considered in the same category as polyfoam with regards to deterioration and body impressions.
This will also have chemical residue in the final product; and those looking for something non-toxic should skip this.
Most Talalay latex is blended latex. Talatech latex is a perfect example.
Botanical latex foam rubber is the only foam used in mattresses made with no off gassing chemicals. However, not all latex mattresses are just latex. Mattresses that use latex foam will often have polyurethane foam layers, or even memory foam layers. For example, an 8" latex mattress may not necessarily be all latex. Manufacturers and retailers are notorious for "bending" the meaning of words. An 8 inch thick mattress may have only 2 inches of latex. Still, they can, and many do, call it an "8 inch All Natural Latex" mattress. Even worse they may call the poly foam soy latex (which is ridiculous).
With every mattress purchase, it is a good idea to verify the components of a mattress that you are considering. It is perfectly permissible to ask to see the manufacturer's spec sheet. After all, it is your money that is being spent and you have a right to make sure that you will get what you expect to get.