Natural Latex (NR) is derived from the Hevea brasiliensis (Rubber Tree). Originally native to Northern Brazil, all latex rubber now comes from plantations in South East Asia. This move can be traced back to the late 19th century when the British explorer Henry Wickham took seedlings from Brazil delivered them to London. The seedlings were then redistributed throughout the British colonies in Asia. Due to a similar climate and geographic profile to Brazil, Southern Asia was the perfect location for rubber plantations. All natural and organic rubber now comes from this region.
It takes 5-7 years before a Rubber Tree can be tapped for its latex potential, and a properly tapped Hevea tree can produce latex for 30 years. Many people incorrectly label latex as tree sap. The milky white raw latex comes from the lactiferous vessels in the bark of the tree while sap comes from the deeper cambium layer. Tapping is done twice a week before dawn except during the dry season when no tapping is done at all.
It takes a very skilled tapper to correctly tap a Rubber Tree as the they must make a careful spiral incision that is deep enough to sever the lactiferous vessels but not so deep as to damage the cambium layer. The raw latex extracted from the tree is known as field latex.
The field latex is collected several hours after tapping and sent to a local processing facility. Field latex is a mix of latex, water and natural byproduct. The latex to water ratio can vary in field latex so it need to be run through a centrifuge to concentrate the liquid rubber. Once a uniform latex to water ratio is achieved the liquid latex is ready to be converted into a foam rubber.
There are two processes used to convert liquid latex into a solid foam, Dunlop and Talalay. There are more similarities than differences between the two methods, so we will explain the Dunlop process first and note their differences later.
The Dunlop process begins by pumping concentrated liquid latex into a mixing tank where it’s whipped into a froth. Once frothed, the semi-solid latex is poured into an open mould.
Once the mould is filled, it’s closed and sent on a conveyor through a vulcanization oven. Vulcanization is the heating process that creates the permanent structural bonds required to convert the liquid rubber into a solid foam rubber.
Once the vulcanization process is complete, the latex foam is removed from the mould and sent to a washing station. During this step the latex is squeezed and washed with purified water to remove any residual impurities remaining from the manufacturing process. The washed latex is then dried and cured to remove all the water remaining in the latex.
The last step is quality control. All latex slabs are weighed, measured and ILD tested to ensure the highest level of consistency possible from batch to batch.
The only major difference between the Talalay and Dunlop process happens during the second step. In the Talalay process, the semi-solid froth is poured into a closed mould and injected with a CO2 blowing agent before being flash frozen. This results in a bouncy, less dense latex foam rubber.
Regardless of the process, all latex can made with or without synthetic latex and with or without filler. These additives make much more of difference in terms of feel and quality than the process itself. That is why using organic latexis much more important than the manufacturing process itself.
In general terms, the denser latex created through the Dunlop process is better suited for organic and 100% natural latex whereas the less dense latex foam made through the Talalay process is better suited for natural and synthetic mixes.
Now that you have a better idea on how latex rubber is created click to learn about the sleep benefits of latex rubber.